Laser Spectroscopy

This study presents a comprehensive study of a driven degenerate Λ-type three-level laser system utilizing a squeezed vacuum reservoir to enhance its performance. The interaction between the laser medium and the squeezed vacuum field is analyzed, revealing significant improvements in coherence and output characteristics. By employing a Λ-type configuration, we explore the population inversion dynamics and the role of squeezed states in reducing quantum noise, ultimately leading to enhanced laser stability and efficiency. Theoretical models are developed to describe the laser dynamics, incorporating the effects of external pumping and the non-classical properties of the squeezed vacuum. Numerical simulations demonstrate that the incorporation of squeezed states leads to a notable increase in the laser's output power and spectral purity compared to traditional systems. These findings suggest that squeezed vacuum reservoirs can serve as a powerful tool for advancing the capabilities of three-level laser systems, with potential applications in quantum optics, communication technologies, and precision measurement. The quest for more efficient and stable laser systems has led to significant advancements in the field of quantum optics 1-5 , particularly in the exploration of non-classical light sources. Among the various configurations studied, the Λ-type three-level laser system has garnered considerable attention due to its unique ability to facilitate population inversion and enhance coherence properties 6-9. In a typical Λ-type configuration 10,11 , two lower energy states are coupled to a common upper state, allowing for effective control over the laser dynamics through tailored pumping schemes. Recent research has highlighted the potential of squeezed vacuum states 12,13 , quantum states of light characterized by reduced uncertainty in one quadrature at the expense of increased uncertainty in the conjugate quadrature to improve the performance of laser systems 14-16. These squeezed states can significantly mitigate quantum noise, which is a critical limitation in conventional lasers 17-19. By incorporating a squeezed vacuum reservoir into a driven degenerate Λ-type three-level laser 16,20,21 , it becomes possible to exploit these nonclassical properties, leading to enhanced output characteristics and stability. In this study, we investigate the interaction between a driven degenerate Λ-type three-level laser and a squeezed vacuum reservoir 22-26. We aim to elucidate how the introduction of squeezed states affects the dynamics of population inversion, coherence, and overall laser output. Through theoretical modeling and numerical simulations, we provide insights into the advantages offered by this innovative approach, paving the way for potential applications in advanced quantum communication systems 27 , precision measurement techniques, and other fields requiring high-performance laser sources 18. It is crucial to express some impact of quantum noise like that phase noise and linewidth broadening: Quantum noise introduces phase fluctuations in the laser output, leading to broadening of the laser linewidth. This can degrade the coherence properties of the laser, which is particularly detrimental in applications requiring high spectral purity, such as precision spectroscopy and quantum communication 27. Furthermore, quantum noise can cause fluctuations in the intensity of the laser output. These intensity fluctuations can reduce the signal-to-noise ratio (SNR) in applications like optical communications and sensing, making it harder to detect weak signals 28. In a degenerate Λ-type three-level system, quantum noise can lead to fluctuations in the population inversion. This instability can cause variations in the gain of the laser, leading to unpredictable output power and potentially lasing threshold fluctuations 20,21. In addition to this, in a Λ-type system, quantum noise can induce quantum beat noise due to the coherent superposition of the two lower states 28. This can result in additional noise components in the laser output, complicating the noise characteristics and potentially degrading the performance of the laser in sensitive applications 14,29,30 .

Acoustic modulation of quantum dots (QDs) allows one to control the scattering of photons. Here we theoretically characterize the degree of this acoustic control in the frequency domain. We formulate the theory of low-intensity resonance fluorescence (RF) in the presence of white noise and show that a high level of control is achievable with a two-tone acoustic field for appropriate settings of modulation amplitudes as long as the noise-induced phase diffusion coefficient remains one order of magnitude smaller than the acoustic frequency. In addition, using a quantitative model of optical signal collection, we determine that the acoustic phase must be stable over 10 4 to 10 5 acoustic periods for efficient control.

The 3p u D 3 ⌺ u + Rydberg state of N 2 is studied experimentally using two high-resolution spectroscopic techniques. First, the forbidden D 3 ⌺ u + -X 1 ⌺ g + transition is observed for the first time via the ͑0,0͒ band of 14 N 2 and the ͑1,0͒ band of 15 N 2 , using 1 extreme-ultraviolet +1 ultraviolet two-photon-ionization laser spectroscopy. Second, the Rydberg-Rydberg transition D 3 ⌺ u + -E 3 ⌺ g + is studied using near-infrared diode-laser photoabsorption spectroscopy, thus extending the previous measurements of Kanamori et al. ͓J. Chem. Phys. 95, 80 ͑1991͔͒, to higher transition energies, and thereby revealing the ͑2,2͒ and ͑3,3͒ bands. The combined results show that the D͑v =0-3͒ levels exhibit rapidly increasing rotational predissociation as v increases, spanning nearly four orders of magnitude. The D-state level structure and rotational predissociation signature are explained by means of a coupled-channels model which considers the electrostatically coupled 3 ⌸ u Rydberg-valence manifold, together with a pure-precession L-uncoupling rotational interaction between the 3p u D 3 ⌺ u + and 3p u G 3 ⌸ u Rydberg p-complex components.

H A method for detection of aromatic organics in groundwater has been tested. It was found that use of surface-enhanced Raman scattering and an octadecylthiol coating on roughened silver produced a system which could partition the organics out of water into the strongly Raman enhanced region near the silver surface. The selectivity of the method was illustrated with the three isomers of xylene. Sensitivity was tested with benzene and naphthalene. The detection limits are 7.5 and 2.3 ppm for benzene and naphthalene, respectively. It was found that the calibrations followed a Langmuir-type isotherm at low solution concentrations.

High precision half-life measurement of the isobaric analogue decay of 29 P 1 P.D. SHIDLING, V. E. IACOB, J.C. HARDY, G. CHUBAR-IAN, V. KOLHINEN, D. MCCLAIN, M. NASSER, ASIM OZMETIN, H.I. PARK, B.T. ROEDER, A. SAASTAMOINEN, BENJAMIN SCHROEDER, DAN MEL-CONIAN, Cyclotron Institute, Texas AM University, FUNDAMENTAL WEAK INTERACTION TEAM -A set of five mirror nuclei are currently being used as an independent source to test the unitarity of the CKM matrix, including 29 P which is currently the least precise of the set. The precision of the ft value is currently limited by the 0.14% uncertainty in the half-life. In order to improve the world half-life value, a precision half-life measurement of 29 P has been performed using the MARS spectrometer and a fast-tape-transport system. The 29 P was produced via the p( 30 Si,2n) 29 P reaction in inverse kinematics at a primary beam energy of 24 MeV/u. The MARS spectrometer transported the secondary beam and implanted the 29 P in an aluminized Mylar tape with purity greater than 99.9%. The fasttape-transport system, quickly transported the sample to a well shielded location, stopping it in the center of the gas-flow proportional counter. The recorded data was separated into several runs, each characterized by a different combination of experimental conditions. An overview of this 0.02 % measurement will be presented.

Thermal fluctuation of the cantilever position sets a fundamental limit for the precision of any Scanning Force Microscope. In the present work we analyse how these fluctuations limit the determination of the resonance frequency of the tip-sample system. The basic principles of frequency detection in Dynamic Scanning Force Microscopy are revised and the precise response of a typical frequency detection unit to thermal fluctuation of the cantilever is analysed in detail. A general relation for thermal frequency noise is found as a function of measurement bandwidth and cantilever oscillation. For large oscillation amplitude and low bandwidth, this relation converges to the result known from the literature, while for low oscillation amplitude and large bandwidth we find that the thermal frequency noise is equal to the width of the resonance curve and therefore stays finite, contrary to what is predicted by the relation known so far. The results presented in this work fundamentally determine the ultimate limits of Dynamic Scanning Force Microscopy.

This paper attempts to revise the classical approach to analyzing spectroscopic data of the
hydrogen atom, with particular emphasis on the reference datasets published by NIST. The
starting point is the question of the nature of energy transfer within the atom: does it occur
chaotically or according to an ordered resonance structure? Intuitively and analytically, we
conclude that order—expressed through harmonic relationships—is more probable than
randomness.
In this work, the energy values were transformed into fractional, unrounded form,
enabling precise identification of resonances between spectral lines. A number of simple (e.g.,
3:1) and complex (e.g., 5:3) resonances were identified, indicating the existence of deep harmonic
structure in the hydrogen emission spectrum. For example, the H(5→4) wave is exactly the third
harmonic of the H(20→10) wave, which was confirmed both analytically and based on NIST
data within the uncertainty range .
of subquantization was also introduced , postulating the existence of a fundamental
energy unit ε₀ ~ 7.71 × 10⁻⁵ eV , multiples of which describe all electronic transitions in the
hydrogen atom. Based on this, a lattice of resonances was constructed with a modulus of around
18.64 GHz, in which all identified emission waves are integer multiples of one fundamental
wavelength λ₀ at that frequency.
The conclusions indicate that the current NIST tables ignore important resonance
relationships between spectral lines, treating them as independent values. Accounting for these
relationships can significantly improve data precision, with potential applications in cosmology,
high-resolution spectroscopy, and atomic energy structure studies. This work invites further
collaboration and the development of analytical tools based on resonance calibration of spectral
data.

Current optical fiber communication is increasingly limited by bottlenecks such
as channel utilization or hardware limitations, highlighting the need for more
efficient systems. Manipulating the information system by encoding the infor-
mation in higher-order bases (binary to hexadecimal) and using permutations
and several properties of tunable lasers, such as phase and wavelength, can pro-
duce higher data transmission speeds. We propose a solution through phase
and chromatic modulation by tuning laser frequencies and laser drive currents
along with permutation encoding. Signals are decoded by spectroscopes, which
detect phase and color after being corrected. Most importantly, this system
operates under the limit established by Shannon’s theorem for noisy channels.
This multi-dimensional approach provides a terabit-scale throughput depending
on the number of lasers in the array (6 Tb/s to 230 Tb/s, or 27 to 32 bits per
symbol per laser). This system gives higher data rates than current telecom
technology. It also offers a higher information density with reduced energy and
cost.

Respired CO 2 in woody tissues radially diffuses to the atmosphere or it is transported upward with the transpiration stream, making the origin of CO 2 in stem CO 2 efflux (E A ) uncertain, which may confound stem respiration (R S ) estimates. An aqueous 13 Cenriched solution was infused into stems of Populus tremula L. trees, and real-time measurements of 13 C-CO 2 and 12 C-CO 2 in E A were performed via Cavity Ring Down Laser Spectroscopy (CRDS). The contribution of locally respired CO 2 (L CO2 ) and xylemtransported CO 2 (T CO2 ) to E A was estimated from their different isotopic composition. Mean daily values of T CO2 /E A ranged from 13% to 38%, evidencing the notable role that xylem CO 2 transport plays in the assessment of stem respiration. Mean daily T CO2 / E A did not differ between treatments of drought stress and light exclusion of woody tissues, but they showed different T CO2 /E A dynamics on a sub-daily time scale. Sub-daily CO 2 diffusion patterns were explained by a light-induced axial CO 2 gradient ascribed to woody tissue photosynthesis, and the resistance to radial CO 2 diffusion determined by bark water content. Here, we demonstrate the outstanding potential of CRDS paired with 13 C-CO 2 labelling to advance in the understanding of CO 2 movement at the plant-atmosphere interface and the respiratory physiology in woody tissues.

In Photoacoustic experiments and low frequency Photodiode applications, Phase sensitive detection is one of the basic operations performed by a lock-in amplifier. Regrettably, it is common to use only basic functions of those devices, in spite of their high cost. The objective of this research is to show the results that were obtained from the development and design of a basic phase shift sensitive device using reconfigurable hardware, which allows a reduction in experimental costs while generating the possibility to apply the developed device in different research fields.

The present paper is a first feasibility study for the SONOLINO project which aims at developing a new method of in-situ diagnostics for the characterization of combustion nanoparticle structure in aerosol phase by using their non-linear optical behavior.

The project’s results will provide a new understanding about the particles’ maturity and composition and will thus in the long-term help to analyze air quality and particle toxicity and to reduce the production of air pollutants.

We report a novel external cavity laser diode (λ = 1.5 µm). An intra-cavity liquid crystal pixel mirror allows digitally tuning of the laser wavelength to more than 40 wavelength channels of 100 GHz spacing according to the International Telecommunication Union (ITU) grid. Laser wavelength can further be fine-tuned by varying the driving voltages applied to an intra-cavity planar nematic liquid crystal phase plate. With a cell 52.3 µm in thickness, the output frequency can be continuously tuned over 1.89 GHz. The root-mean-square voltage required for driving the phase plate was from 1.00 to 4.56 volts.

We report a continuous-wave (cw) source of tunable mid-infrared radiation providing tens of milliwatt of output power in the 6460-7517 nm spectral range. The source is based on difference-frequency generation (DFG) in orientation-patterned (OP)-GaAs pumped by a Tm-fiber laser at 2010 nm and a 1064 nm-Yb-fiber-pumped cw optical parametric oscillator. Using a 25.7-mm-long OP-GaAs crystal, we have generated up to 51.1 mW of output power at 6790 nm, with >40 mW and >20 mW across 32% and 80% of the mid-infrared tuning range, respectively, which is to the best of our knowledge the highest tunable cw power generated in OP-GaAs in this spectral range. The DFG output at maximum power exhibits passive power stability better than 2.3% rms over more than 1 h and a frequency stability of 1.8 GHz over more than 1 min, in high spatial beam quality. The system and crystal performance at high pump powers have been studied.

Outline PART I  Motivation for a post-accelerator: ReA  Reacceleration concept  ReA EBIT charge breeder PART II  Results of on-line operation: o Charge-breeding efficiencies o Stretching of EBIT pulses (ejected ion time distributions) o Contamination study Conclusion Started on-line operation in Sept 2015 How does the entire system work? T 4 The ReAcceleration concept Light ions: 0.3 -6 MeV/u ( 48 Ca) Heavy ions: 0.3 -3 MeV/u ( 238 U) • Silicon b-decay counters integrated to Faraday cups.

Laser-Induced Breakdown Spectroscopy (LIBS) is a new source of distinct role which is now being widely used as an efficient, fast and more versatile method of analysis in soil analysis which has contributed to the best sustainable practice of agriculture. The objective of this review is to provide a comprehensive overview of recent advancements in the application of LIBS for soil analysis, with a particular focus on its role in the detection and quantification of soil nutrients and contaminants. This review aims to highlight how LIBS contributes to improving analytical accuracy, enhancing real-time monitoring capabilities, and supporting sustainable agricultural practices through precise soil characterization. More recent developments have centered on defeating some of the critical drawbacks of LIBS accuracy, including matrix effects, moisture content, and variability of particle size. Optimized experimental procedures, such as spatial confinement, addition of a conductive material and laser-induced fluorescence (LIF) support have shown significant increases in detection limit and precision of the analytical method. The combination of machine learning, deep learning, and chemometric processes continue to optimize LIBS applications by allowing predictive models that can withstand the balkier soil matrices. Moreover, portable and handheld LIBS have contributed to its use in field based real time soil monitoring. Reproducibility is being promised by efforts of standardization through certified reference materials and interlaboratory protocols into increasing acceptance by the scientific community. All these innovations make LIBS one of the most promising instruments in terms of accurate soil nutrient management and contamination testing, with valuable security providing strategic resources, resource-efficient and environmentally sustainable agricultural systems.

Collinear Laser Spectroscopy at the BECOLA Facility ANTHONY SCHNEIDER, ANDREW KLOSE, PAUL MANTICA, SOPHIA VINNIKOVA, Michigan State University, KEI MINAMISONO, NSCL, BECOLA TEAM -The BEam COoler and LAser spectroscopy (BECOLA) facility has been constructed at NSCL to measure the hyperfine structure of nuclei and deduce moments and charge radii. A Colutron off-line ion source is being used to produce stable isotope beams to commission the collinear laser beam line. Laser light is transported to the beam line via fiber optic cable and is collinearly aligned with the stable, low-energy (< 60 keV) beam. The hyperfine structure is extracted by observing the fluorescence as a function of the acceleration voltage of the beam, which is equivalent to scanning the laser frequencies due to the Doppler Effect. The operational characteristics and controls of the off-line source and collinear beam line will be discussed.

Molecular overtone transitions provide optical frequency transitions sensitive to variation in the proton-to-electron mass ratio (&mu; = mp/me). However, robust molecular state preparation presents a challenge critical for achieving high precision. Here, we characterize infrared and optical-frequency broadband laser cooling schemes for TeH+, a species with multiple electronic transitions amenable to sustained laser control. Using rate equations to simulate laser cooling population dynamics, we estimate the fractional sensitivity to&nbsp;&mu; attainable using TeH+. We find that laser cooling of&nbsp;TeH+ can lead to significant improvements on current &mu; variation limits.

The daguerreotype, introduced by Louis-Jacques-Mandé Daguerre in 1839, marked the beginning of photography. This early photographic process, based on halide-sensitized silver-coated copper plates developed with mercury vapor, produces highly reflective, image-bearing surfaces that are both visually unique and chemically complex. As part of the interdisciplinary Heritage Science project PHELETYPIA, this study investigates the surface morphology and elemental composition of two historical daguerreotypes from the Varaždin City Museum (Croatia) using monochromatic micro-x-ray fluorescence (μXRF), scanning electron microscopy with energy-dispersive x-ray spectrometry (SEM/EDS), and optical microscopy. By comparing elemental distribution maps based on Hg-L and Au-L lines, we assess the relationship between image particle composition, visual contrast, and degradation patterns. Our results suggest that differences in image formation and preservation are linked to original manufacturing processes, including uneven thermal development and subsequent environmental exposure. High-resolution elemental imaging reveals how visual information is distributed across tonal zones and how it may be affected by previous conservation interventions. These findings highlight the potential of non-invasive analytical imaging to enhance our understanding of daguerreotype image structure, support condition assessment, and inform long-term digital preservation strategies.

The effect of laser radiation on the formation of film-like deposits on the surface of optical parts located in closed volumes containing sealants such as VGO-1, KLT-30, U-2-28, and K-68 has been studied. X-ray photoelectron spectroscopy and IR spectroscopy were used to determine the composition of the film-like deposits. The composition of the gas medium was determined by mass spectrometry. The formation kinetics of film-like deposits were investigated as a function of the medium temperature and the laser radiation parameters. Possible formation mechanisms of the  lm-like deposits and methods for their elimination were considered.

In this work we report growth of Y 3 Sc 2 Al 3 O 12 (YSAG) doped with trivalent ions of neodymium and praseodymium, by means of the Micro-Pulling-Down (l-PD) technique and the study of their optical properties by means of spectroscopic analysis.

Molybdenum targets were irradiated with 2-ns 300-mJ pulses from an Nd:YAG laser at its second harmonic wavelength of 532 nm at a repetition rate of 10 Hz in open air. The radiation emitted from laser-induced plasma from the Mo target in the Local Thermal Equilibrium (LTE) state was analyzed. The temperature of the plasma was calculated using a Boltzmann-plot method. The electron density was determined from the Stark broadening via the comparison of the electron densities of different neutral molybdenum lines (465.5, 498, 517 and 550 nm) with hydrogen H α-line (656.3 nm). We studied the variation of electron density and electron temperature as a function of μs-delay times and laser fluencies at different distances from the target surface. It was found that the neutral molybdenum lines suffer from self-absorption. The self-absorption changes the values of the electron density and the electron temperature due to the decrease in the line intensity and the increase in the line width and hence leads to the distortion in the line shape. The Mo I lines were corrected against self-absorption and the corrected values of the temperature and the electron density were obtained. REVISED

We read with interest Saxby et al.'s correspondence regarding their experience of managing periocular basal cell carcinoma (BCC) in the under 40s cohort . Currently our periocular cancer service employs a dermatologist Mohs surgeon for excision followed by reconstruction under the Oculoplastic team. Auditing our own under 40s cohort of patients, we found 11 patients with biopsy proven BCC over a 4-year period with an average age of 32 and mean follow up of 8.5 months. We found 91% (10/11) excisions to be of nodular histological subtype with only one Infiltrative BCC and unlike Saxby et al. found no patients to have morphoeic tumours. A study of 134 patients with <1 cm well demarcated facial BCCs found that 24% required further excision when excised with 2 mm margins [2]. However, it has been shown that 21.8% of all BCCs have a morphoeic or partly morphoeic histology . This may explain why seemingly nodular BCCs may have asymmetric subclinical extensions that result in incomplete excision when 2 mm margins are used. We strongly support their recommendation that Mohs surgery be considered for periocular BCC in the under 40s, especially with the need for complete tumour extirpation and to minimise tissue loss in a cohort with a paucity of skin elasticity where defect repairs can often be challenging.

This study investigates new methods in the Jordanian museums in cleaning of ancient materials by laser cleaning of corrosion or patina products on archaeological corroded objects. This aproach aiming to introduce a methodology for the optimal laser cleaning attitude in archaeological artefacts in Jordanian meuseums. It is study focused on the feasibility of YAG Laser in cleaning of Archaeological artefacts both organic and inorganic that covered with a corrosion or crust. The clustering of inclusion particles of the patina some are hard to remove by the procedure of conventional cleaning techniques, there is an apparent danger by use the traditional methods. These methods escalate the risk of the oxidised corrosion layer breaking away which will lead to loss of details about the the object and other important surface information. The advantage of using YAG pulsed lasers for cleaning of archaeological artefacts patina or corrosion. The lasr technique is well precised controlled and c...

Polyaniline emeraldine salt (PANI-ES) is a conductive polymer with promising optoelectronic properties, synthesized via chemical oxidative polymerization and confirmed in its emeraldine salt form through structural analysis. Optical characterization revealed distinct absorption bands linked to key electronic transitions, indicating semiconducting behavior. Under UV excitation, photoluminescence studies showed two main emission features corresponding to dimer and excimer states, both exhibiting large Stokes shifts and a quantum yield of 0.27. These long Stokes shifts suggest efficient energy relaxation, while the moderate quantum efficiency highlights the material's capability for light-emitting applications. The combination of tunable emission, stable optical response, and electrical conductivity positions PANI-ES as a versatile material for photonic technologies. Potential applications include organic light-emitting diodes (OLEDs), photodetectors, and optically pumped organic lasers. Overall, the study demonstrates that PANI-ES offers a favorable balance of structural stability, optical performance, and electronic properties, making it a strong candidate for integration into advanced optoelectronic and photonic devices.

We report a systematic measurement of the space charge effect observed in the few-picosecond laser pulse regime in laser-based solid-state photoemission spectroscopy experiments. The broadening and the shift of a gold Fermi edge as a function of spot size, laser power, and emission angle are characterized for pulse lengths of 6 ps and 6 eV photon energy. The results are used as a benchmark for an N-body numerical simulation and are compared to different regimes used in photoemission spectroscopy. These results provide an important reference for the design of time- and angle-resolved photoemission spectroscopy setups and next-generation light sources.

April, 2007 PROGRESS IN PHYSICS Volume 2 Fast LIBS Identification of Aluminum Alloys Walid Tawfik Y. Mohamed National Inst. of Laser Enhanced Science NILES, Dept. of Environmental Applications, Cairo University, Cairo, Egypt Faculty of Education for Girls, Department of ...

Laser-induced breakdown spectroscopy (LIBS) has been used as a remote sensing system to analyze seawater samples and to identify their salinities without ordinary calibration curves. The plasma is generated by focusing a pulsed Nd: YAG laser on the seawater surface in air at atmospheric pressure. Such plasma emission spectrum was collected using wide band fused-silica optical fiber of one-meter length connected to a portable Echelle spectrometer (Mechelle 7500 -Multichannel Instruments, Stockholm, Sweden) with intensified CCD camera. Spectroscopic analysis of plasma evolution of laser produced plasmas has been characterized in terms of their spectra, electron density and electron temperature assuming the local thermodynamic equilibrium (LTE) and optically thin plasma conditions. Three elements Na, Ca and Mg were determined in the obtained spectra to identify the salinity of seawater samples. The electron temperature T e and density N e were determined using the emission intensity and Stark broadening. The obtained values of T e and N e for natural seawater sample (salinity 3.753%) are 11580 K ± 0.35% and 3.33×10 18 cm -3 ± 14.3%. These values exhibit a significant change only if the matrix changes (i.e., the salinity changes). On the other hand, no significant difference was obtained if T e and N e were determined using any of the three elements (Na, Ca and Mg) in the same matrix. It is concluded that T e and N e represent a fingerprint plasma characterization for a given seawater sample and its salinity could be identified using only one element without need to analyze the rest of elements in the seawater matrix. The obtained results indicate that it is possible to improve the exploitation of LIBS in the remote on-line environmental monitoring, by following up only a single element as a marker to identify the seawater matrix composition and salinity without need to analyze that matrix which saves a lot of time and efforts.

Laser-induced breakdown spectroscopy (LIBS) is a laser-based technique that can provide non-intrusive, qualitative and quantitative measurement of metals in various environments. LIBS uses the plasma generated by a high-energy laser beam to prepare and excite the sample in one step. In the present work, LIBS has been applied to perform elemental analysis of six trace elements simultaneously in aluminum alloy targets. The plasma is generated by focusing a pulsed Nd:YAG laser on the target in air at atmospheric pressure. LIBS limit of detection (LOD) is affected by many experimental parameters such as interferences, self-absorption, spectral overlap and matrix effect. We aimed to improve the LIBS LOD by optimizing these experimental parameters as possible. In doing so, a portable Echelle spectrometer with intensified CCD camera was used to detect the LIBS plasma emission. This advanced Echelle spectrometer provides a constant spectral resolution (CSR) of 7500 corresponding to 4 pixels FWHM over a wavelength range 200-1000 nm displayable in a single spectrum. Then, the calibration curves for iron, beryllium, magnesium, silicon, manganese and copper as minor elements were achieved with linear regression coefficients between 98-99% on average in aluminum standard sample alloys. New LOD values were achieved in the ppm range with high precision (RSD 3-8%). From the application view point, improving LIBS LOD is very important in the on-line industrial process control to follow-up multi-elements for the correct alloying in metals.

April, 2007 PROGRESS IN PHYSICS Volume 2 Fast LIBS Identification of Aluminum Alloys Walid Tawfik Y. Mohamed National Inst. of Laser Enhanced Science NILES, Dept. of Environmental Applications, Cairo University, Cairo, Egypt Faculty of Education for Girls, Department of ...

Number of trace compounds (called biomarkers), which occur in human breath, provide an information about individual feature of the body, as well as on the state of its health. In this paper we present the results of experiments about detection of certain biomarkers using laser absorption spectroscopy methods of high sensitivity. For NO, OCS, C

Parity violation (PV) effects in chiral molecules have so far never been experimentally observed. To take up this challenge, a consortium of physicists, chemists, theoreticians, and spectroscopists has been established and aims at measuring PV energy differences between two enantiomers by using high‐resolution laser spectroscopy. In this article, we present our common strategy to reach this goal, the progress accomplished in the diverse areas, and point out directions for future PV observations. The work of André Collet on bromochlorofluoromethane (1) enantiomers, their synthesis, and their chiral recognition by cryptophanes made feasible the first generation of experiments presented in this article. Chirality, 2010. © 2010 Wiley‐Liss, Inc.

Here, we describe an innovative Integrated Laser Sensor (ILS) that combines four spectroscopic techniques and two vision systems into a unique, transportable device. The instrument performs Raman and Laser-Induced Fluorescence (LIF) spectroscopy excited at 355 nm and Laser-Induced Breakdown Spectroscopy (LIBS) excited at 1064 nm, and it also detects Laser Scattering (LS) from the target under illumination at 650 nm. The combination of these techniques supplies information about: material change from one scanning point to another, the presence of surface contaminants, and the molecular and elemental composition of top target layers. Switching between the spectroscopic techniques and the laser wavelengths is fully automatic. The instrument is equipped with an autofocus, and it performs scanning with a chosen grid density over an interactively-selected target area. Alternative to the spectroscopic measurements, it is possible to switch the instrument to a high magnification target view...

Multiplexed analysis allows simultaneous measurements of multiple targets, improving the detection sensitivity and accuracy. However, highly multiplexed analysis has been challenging for point-of-care (POC) sensing, which requires a simple, portable, robust, and affordable detection system. In this work, we developed paper-based POC sensing arrays consisting of kaleidoscopic fluorescent compounds. Using an indolizine structure as a fluorescent core skeleton, named Kaleidolizine (KIz), a library of 75 different fluorescent KIz derivatives were designed and synthesized. These KIz derivatives are simultaneously excited by a single ultraviolet (UV) light source and emit diverse fluorescence colors and intensities. For multiplexed POC sensing system, fluorescent compounds array on cellulose paper was prepared and the pattern of fluorescence changes of KIz on array were specific to target chemicals adsorbed on that paper. Furthermore, we developed a machine-learning algorithm for automated, rapid analysis of color and intensity changes of individual sensing arrays. We showed that the paper sensor arrays could differentiate 35 different volatile organic compounds using a smartphone-based handheld detection system. Powered by the custom-developed machine-learning algorithm, we achieved the detection accuracy of 97 % in the VOC detection. The highly multiplexed paper sensor could have favorable applications for monitoring a broad-range of environmental toxins, heavy metals, explosives, pathogens.

Temperature Effects in Up-Conversion Processes of Erbium - Ytterbium Doped Oxyfluoride Silicate GlassEr3+- Yb3+doped oxyfluoride glass has been synthesized and investigated. It was found that the up-conversion spectrum of the sample excited by a 980 nm laser diode is highly dependent on the temperature of the sample. Using fluorescence intensity ratio technique the green up-conversion emissions at 525 nm and 550 nm were studied in detail in the temperature range 120-600 K. The potential applicability of the obtained results in the field of the temperature sensing is discussed.

Background: NO2 detection is necessary because NO2 is an air pollutant causing photochemical smog and acid rain. In addition, respiratory diseases are caused by high levels of NO2 in the inhaled air. Aim: The purpose of this study was to detect NO2 using PAS utilizing Arduino Uno, an easy, simple, and low-cost research. Methods: The detection of Nitrogen Dioxide (NO2) gas with a Photoacoustic Spectrometer (PAS) using an Arduino Uno microcontroller has been carried out. The PAS system uses a blue diode laser with a wavelength of 450 nm as the radiation source because this wavelength is suitable for NO2 gas. The intensity of the laser beam is modulated using a modulation system with an on-off scheme using the Arduino Uno. The modulation frequency has been varied to get the maximum detection frequency. The photoacoustic cell used was a single resonator photoacoustic cell with type H. Sound sensor and photodiode were used in this measurement. The amplification of the signal was done by ...

Precision spectroscopy of light muonic atoms provides unique information about the atomic and nuclear structure of these systems and thus represents a way to access fundamental interactions, properties and constants. One application comprises the determination of absolute nuclear charge radii with unprecedented accuracy from measurements of the 2S -2P Lamb shift. Here, we review recent results of nuclear charge radii extracted from muonic hydrogen and helium spectroscopy and present experiment proposals to access light muonic atoms with Z ≥ 3. In addition, our approaches towards a precise measurement of the Zemach radii in muonic hydrogen (µp) and helium (µ 3 He + ) are discussed. These results will provide new tests of bound-state quantum-electrodynamics in hydrogen-like systems and can be used as benchmarks for nuclear structure theories.

Background. The security and privacy communities have become increasingly interested in results from behavioral economics and psychology to help frame decisions so that users can make better privacy and security choices. One such result in the literature suggests that cognitive disfluency (presenting questions in a hard-to-read font) reduces selfdisclosure. • Aim. To examine the replicability and reliability of the effect of disfluency on self-disclosure, in order to test whether such approaches might be used to promote safer security and privacy behaviors. • Method. We conducted a series of survey studies on human subjects with two conditions -disfluent and fluent font. The surveys were completed online (390 participants throughout the United States), on tablets (93 students) and with pen and paper (three studies with 89, 61, and 59 students). The pen and paper studies replicated the original study exactly. We ran an independent samples t-test to check for significant differences between the averages of desirable responses across the two conditions. • Results. In all but one case, participants did not show lower self-disclosure rates under disfluent conditions using an independent samples t-test. We re-analyzed the original data and our data using the same statistical test (paired t-test) as used in the original paper, and only the data from the original published studies supported the hypothesis. • Conclusions.We argue that the effect of disfluency on disclosure originally reported in the literature might result from the choice of statistical analysis, and that disfluency does not reliably or consistently affect self-disclosure. Thus, disfluency may not be relied on for interface designers trying to improve security or privacy decision making.

tpcnmcrd b* the IMttd Slim Gumniwni Nciiho iht tlMM SUM HOI iht liuitd Sum tntw Rntvch i*d Drxlopmrnt Ail MMMMMmrf VitK tngtoytn, MI in* ol Ihtu cantncimi. lubcofilncloit. ot ihtu tRip1a>H>, m*fc« ••> Mittnit. capita DI iavlwd •» tuirti >n> ktil bMity or mpoiuHillilr !m Iht ii^HVilt'wflijMiwl Mangi (win Id) awntdr<fhli.

An analytical study, corroborated by Monte Carlo simulations, is presented which describes the interaction of a 300  keV–830 mA proton beam with a Cu and Al dumping system. The analytical calculations rely on the theoretical framework of the Particle Induced X-ray Emission, while the Monte Carlo simulations are performed by means of the GEANT4 toolkit. The case study is related to the project SORGENTINA-RF fusion neutron source and in particular to the tests devoted to assess the performance of the ion source of the plant. The results provide a detailed physical insight of the main processes occurring in the beam dump material, and are also important to give some realistic figures of the radiation emission expected during operation.

espanolEn el presente trabajo se estudia la respuesta en fluorescencia de un vapor de Rubidio confinado en los intersticios de una celda de vidrio poroso, sistema altamente difusivo para la luz. El interes es el de estudiar las consecuencias espectroscopicas asociadas al confinamiento espacial de los atomos. La transicion seleccionada posee un tiempo de vida medio del estado excitado mayor al tiempo medio de vuelo de los atomos en el poro. Este estado atomico es alcanzado mediante la excitacion del atomo por dos campos de diferentes frecuencias. Los espectros de fluorescencia obtenidos presentan formas inusuales, y son bien descriptos por un modelo teorico sencillo que contempla el caracter difuso de la luz. Si bien los mencionados espectros no dan informacion del confinamiento 3D de los atomos, la accion del confinamiento se ve claramente reflejada al medir el tiempo de decaimiento de la senal de fluorescencia, en donde se observa un acortamiento del tiempo con respecto a la senal ...

The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publishers, the authors, and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publishers nor the authors or the editors give a warranty, express or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publishers remain neutral with regard to jurisdictional claims in published maps and institutional affiliations.

This paper updates Einstein's Theory of Special Relativity's second postulate with the additional five words 'at a given Neutrino Pressure,' which removes time dilation and unlocks a whole new paradigm with the Neutrino Pressure Theory that goes beyond General Relativity and explains the true source of gravity, inertia, and so much more.

Reactive carbocation intermediates are encountered in a myriad of industrially and physiologically important processes, and while the development of methods to generate persistent carbocations in condensed phases led to a flurry of studies culminating in the 1994 Nobel Prize in Chemistry, 1 these important ions have regrettably resisted gas-phase spectroscopic analysis. For example, the infrared spectrum of CH 3 + was not obtained until 1985! 2 To this day, little structural information exists for simple carbocations, such as CH 2 X + (X ) F, Cl, Br, I). These species are observed and their reactions studied with mass spectrometric techniques, 3 and many theoretical studies have been undertaken to predict their structure and spectroscopic properties, 4 yet experimental proof is lacking. In this communication, we report the first gas-phase observation of the electronic spectrum of a halocarbocation, CH 2 I + , which was generated using pulsed discharge techniques and was detected using laser spectroscopy. We believe that this initial detection will open new avenues for study of the structure and reactivity of these important species. The monohalocarbocation CH 2 I + was produced using gas phase pulsed discharge supersonic jet techniques that have been described in detail. A stable precursor, CH 2 I 2 (Aldrich, 99.5% stated purity), seeded in high purity helium at a mole fraction of ∼1%, was subjected to a high voltage discharge pulse of amplitude +1000 V and 700 µs duration. The discharge products expanded into vacuum, leading to significant rotational cooling (T rot ∼ 20 K), and were intersected by the output of a pulsed tunable laser system. The resulting fluorescence was collected, filtered, and detected by a photomultiplier tube, and the signal was passed to a computer for analysis. Wavelength resolved spectra were obtained using a 0.3 m spectrograph with a gated intensified CCD detector. In comparison with previous studies of neutral molecules generated from the same source, 5 the discharge conditions were more critical, and the signal was optimized at a significantly shorter delay setting, which provided the first indication that the carrier of the spectrum was an ion. To confirm its identity, we carried out experiments with diiodomethane-d 2 (Cambridge Isotope labs, >99% atom D). Using the CH 2 I 2 precursor, we initially obtained fluorescence excitation spectra in the region of 580-660 nm, which showed a prominent series of (partially) rotationally resolved bands spaced at ∼570 cm -1 . The origin, at ∼15 180 cm -1 , shifted to ∼15 288 cm -1 when the precursor was replaced with diiodomethane-d 2 , and the band system disappeared when the precursor was changed to CH 3 I or CH 2 ICl. Emission spectra were obtained from the observed bands, and examples are given in Figure ; these show two prominent progressions, in addition to several weaker features. We fit the term energies in these two progressions to a two-mode Dunham expansion to derive an initial set of vibrational parameters, 5 and the experimental harmonic frequencies are listed in Table . These were compared with literature or calculated 6 (B3LYP/6-311G**) frequencies for a variety of candidates, including CHI, CH 2 I, CHI 2 , and their corresponding cations and anions, and CH 2 I 2 + . As shown in Table , excellent agreement was obtained with