Electric Dipole Moments

The electric dipole moments of the isolated amino acid tryptophan and small glycine-based peptides (WGn, n = 1−5, W = tryptophan, G = glycine) have been measured by deflection of a molecular beam in an inhomogeneous electric field. The measurements are compared to the results of ab initio calculations and Monte-Carlo simulations. The conformation and the flexibility of the peptides, at different temperatures, are discussed. The WGn peptides are much more floppy than an isolated tryptophan, even a single glycine is enough to make the peptide floppy on the timescale of the electric deflection measurements.

Experimental data from dielectric investigations of solutions of flourobenzene
(FB) and its mesogenic derivative (1-fluoro-4-(4-pentylcyclohexyl) benzene (FPCHB) in
1,4-dioxane are reported for various mole fractions and temperatures. The molecular dipole
moments were determined using the Guggenheim-Debye method in the temperature
range of 298.2 to 318.2 K. Both fluorinated compounds show a positive and small temperature
coefficient for the effective dipole moment. Variations of the effective dipole moment
and correlation factor, g, with mole fraction in these mixtures were investigated using
the Kirkwood-Frohlich equation. Dielectric measurements were also carried out on binary
mixtures of FPCHB with 1-butanol for various concentrations at 318.2 K. The Kirkwood
correlation factor, the Bruggeman factor, and the excess permittivity were determined.

We have measured the neutron electric dipole moment using spin rotation in a non-centrosymmetric crystal. Our result is d=(2.5±6.5stat±5.5syst).10-24 e.cm. The dominating contribution to the systematic uncertainty is statistical in nature and will reduce with improved statistics. The statistical sensitivity can be increased to 2.10-26 e.cm in 100 days data taking with an improved setup. We state technical requirements for a systematic uncertainty at the same level.

The feasibility of an experiment to search for the neutron electric dipole moment (EDM) by Laue diffraction in crystals without a center of symmetry was tested. At the PF1A beam of the ILL reactor a record time delay of τ~2 ms for the passage of neutrons through a quartz crystal was reached for the (110) plane and diffraction angles equal to 88.5°. That corresponds to an effective neutron velocity in the crystal of 20 m/s, while the velocity of the incident neutron was 800 m/s. It was shown experimentally that the value τN1/2, determining the method's sensitivity, has a maximum for the Bragg angle equal to 86°. The results allow us to estimate the statistical sensitivity of the method for the neutron EDM. For the PF1B beam of the ILL reactor the sensitivity can reach ~6×10-25 ecm per day for the available quartz crystal.

“All Nobel Laureates did not understand how the atom absorbs a photon”
Adrian Ferent

“In Ferent Quantum Gravity the photon is absorbed by the atom as a dipole”
Adrian Ferent

“In Ferent Quantum Gravity the photon is absorbed by the dipole not by the electron”
Adrian Ferent

“In Ferent Quantum Gravity the photon is absorbed by the dipole not by the electron, the interaction between atom and photon has greater probability than the interaction between electron and photon”
Adrian Ferent

“The photon is absorbed by the atom not by the electron”
Adrian Ferent

The combination of geophysical data and geotechnical measurements may greatly improve the quality of buildings under construction in civil engineering. A case study is presented here at a vacant building site. Initially, boreholes indicated a complex geology. A dipole-dipole configuration was selected for electrical resistivity tomography (ERT) implementation and the data were processed and interpreted by applying 2D and 3D inversions. An electromagnetic survey was also carried out at a different time periods and successfully used to verify the results of the resistivity measurements. It is demonstrated that engineering geophysics is able to provide solutions for determining subsurface properties and that different prospection techniques are necessary for developing a reasonable model of the subsurface structure.

The feasibility of an experiment to search for the neutron electric dipole moment (EDM) by Laue diffraction in crystals without a center of symmetry was tested. At the PF1A beam of the ILL reactor a record time delay of s % 2 ms for the passage of neutrons through a quartz crystal was reached for the (1 1 0) plane and diffraction angles equal to 88.5°. That corresponds to an effective neutron velocity in the crystal of 20 m/s, while the velocity of the incident neutron was 800 m/s. It was shown experimentally that the value sN 1=2 , determining the method's sensitivity, has a maximum for the Bragg angle equal to 86°. The results allow us to estimate the statistical sensitivity of the method for the neutron EDM. For the PF1B beam of the ILL reactor the sensitivity can reach $ 6 Â 10 À25 e cm per day for the available quartz crystal.

We discuss the nuclear anapole moment, a new P odd, T even electromagnetic multipole. Its discovery in the cesium experiment gives a first-rate information on parity-nonconserving nuclear forces. New prospects in the field are considered. Upper limits on the electric dipole moments, which are P odd, T odd multipoles, of elementary particles and atoms are presented, and their physical implications discussed. The atomic experiments are demonstrated to be as informative in this respect as the neutron ones. Tremendous progress in the field can be expected from experiments at ion storage rings and linear electrostatic traps.

We carried out first principles calculations to show that polymerizable structures containing hydroxyl (alcoholic chain) and amino groups are suitable to form stable complexes with dibenzothiophene (DBT) and its alkyl derivates. These sulfur pollutants are very difficult to eliminate through traditional catalytic processes. Spontaneous and exothermic interactions at 0 K primarily occur through the formation of stable complexes of organosulfur molecules with monomeric structures by hydrogen bonds. The bonds are formed between the sulfur atom and the hydrogen of the hydroxyl group; additional hydrogen bonds are formed between the hydrogen atoms of the organosulfur molecule and the nitrogen atoms of the monomers. We vary the number of methylene groups in the alcoholic chain containing the hydroxyl group of the monomer and find that the monomeric structure with four methylene groups has the best selectivity towards the interaction with the methyl derivates with reference to the interaction with DBT. Even this study does not consider solvent and competitive adsorption effects; our results show that monomeric structures containing amino and hydroxyl groups can be used to develop adsorbents to eliminate organosulfur pollutants from oil and its derivates.

Highlighting an article from /Atoms/ published in 2019!
Optical Rotation Approach to Search for the Electric Dipole Moment of the Electron
https://www.mdpi.com/2218-2004/7/2/56

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Glycerol droplets at a nematic-liquid-crystal -air interface form two different lattices -hexagonal and dense quasihexagonal-which are separated by the energy barrier and can coexist. Director distortions around each droplet form an elastic dipole. The first order transition between the two lattices is driven by a reduction of the dipole-dipole repulsion through reorientation of these dipoles. The elastic-capillary attraction is essential for the both lattices. The effect has a many-body origin.

The RESPER probe has been assembled, except the ferrules that must ensure the contact, by insulating materials and more specifically in Tufnol, as regards the support plates, and Teflon, as regards the standoffs. A series of holes has been drilled on the surface of support plates in order to allow approaching each other of the two central electrodes to external

“The dipole atom is the volume inside the atom, between electron and proton with the largest number of photons per unit volume”
Adrian Ferent

“The dipole atom has the largest number of photons per unit volume, positive photons emitted by proton and negative photons emitted by electron”
Adrian Ferent

“The absorbed photon is split by the dipole atom in the negative photon and the positive photon”
Adrian Ferent

“The flux of photons inside the dipole atom split the absorbed photon”
Adrian Ferent

This research study aims to examine the effectiveness of a problem-based learning (PBL) on 9th grade students' understanding of intermolecular forces (dipoledipole forces, London dispersion forces and hydrogen bonding). The student's alternate conceptions about intermolecular bonding and their beliefs about PBL were also measured. Seventy-eight 9th grade students were stratified by cognitive levels and then randomly assigned to experimental (PBL, 40 students) and control (lecture-style teaching, 38 students) groups. Following a preparatory lesson where activation and remediation of existing knowledge occur, a pre-test was given, and no significant difference was found between the two groups of students (p>.05). After the instruction was completed, a posttest and also a questionnaire related to the quality of the problem, the teacher's role and group functioning were administered. Results from the post-test of both groups (p<.05) and questionnaire showed that PBL is affective on students' achievement, remedying formation of alternate conceptions and also social skills. Keywords Problem-based learning. Intermolecular forces. Alternate conceptions The main purpose of education is to improve students' learning achievement. According to constructivism, learning is a cognitive process and occurs by construction of knowledge in the mind of the learner (Bodner 1986). Many factors affect this process, the most important of which is the student's prior knowledge and experiences. If the new information is consistent with their prior knowledge, it can be assimilated easily. Nevertheless, such prior knowledge may be scientifically incorrect, and can adversely affect subsequent learning (Jonassen 1991; Resnick 1983; Sanger and Greenbowe 1997). These concepts are labelled alternate conceptions in the literature (Andersson 1986; Ben-Zvi et al. 1986; Brown 1992). Several studies have documented student alternate conceptions of various chemistry subjects which are regarded as difficult and abstract. Research in science education therefore has focused on applying active learning techniques, which ensure the affective

An integrated geophysical survey was carried out in a new dwelling area at 15-May town, southeast Cairo, Egypt. The buildings in this area are intensively affected by dangerous cracks that cause structural instability. The survey aimed to image the shallow subsurface structures, including karstic features, and evaluate their extent, as they may cause rock instability and lead to cracking of the residential buildings. Resistivity profiling (2-D), using a dipole-dipole array and ground penetrating radar (GPR) surveys were carried out along seven parallel traverses extending about 150 meters between the buildings blocks. Additional measurements using a Schlumbereger array and very low frequency electromagnetic (VLF-EM) methods were conducted. The acquired data were processed and interpreted integrally to elucidate the shallow structural setting of the site. Integrated interpretation led to the delineation of hazard zones rich with karstic features in the area. Most of these karstic fea...

In this paper, the response of different synthetic models to geoelectrical multi-electrode surveys is studied. The models considered are related to two main problems, which are very common in geophysical research regarding hydrogeology and engineering. The first class of models represents buried walls, similar archaeological remains or remains of buried foundations; the other class corresponds to a sea-water intrusion of a fresh water aquifer, which is generally studied in hydrogeophysics. A set of 2D simulations, starting from the synthetic models, was carried out to compare the behaviour of the different arrays when acquiring measurements of electrical resistivity tomography. For each model, the apparent resistivity data-and relative pseudo-sections-were calculated for common electrode arrays (Wenner, dipole-dipole, Wenner-Schlumberger). Furthermore, a 'non-classical' configuration (i.e. the linear grid) was also tested. The synthetic data, after adding different levels of Gaussian noise, were inverted using RES2DINV software; then the interpretative models were compared with the initial synthetic models using different parameters to estimate the quality of the matching. Finally, the comparison between the results obtained using the various arrays is presented. Furthermore, the effectiveness of the various arrays is evaluated for each problem, also taking into account some other characteristics of the arrays, including the associated practical advantages in time consumption and noise level. Results on synthetic data were also confirmed by two field tests: one at an archaeological site survey and one at a coastal aquifer study.

Ultraviolet photoelectron spectra were measured for titanyl-and lead-phthalocyanine ultrathin films prepared on graphite in order to study effects of the electric dipole layer on the organic energy levels. Each of these molecules has an electric dipole perpendicular to the molecular plane, and hence a well-defined electric dipole layer could be intentionally prepared by using oriented monolayer of these molecules. For as-grown films, the observed highest occupied molecular orbital (HOMO) band consists of many peaks that could be assigned to different molecular orientations/aggregations. For well-oriented monolayer films obtained by annealing the as-grown films, we observed a very sharp HOMO band with two satellites for both molecules as for copper phthalocyanine. Difference of binding energy of HOMO bands between the oriented monolayer and the doublelayer in which molecular electric dipoles are cancelled was found to agree with the vacuum level shift for both molecules, leading to important conclusions that (1) the molecular energy level with respect to the substrate Fermi level is changed when the molecule is in the dipole layer and (2) the binding-energy shift corresponds with the vacuum level shift.

An experiment searching for the neutron electric dipole moment by measuring spin-rotations in a non-centrosymmetric crystal was carried out to investigate the statistical sensitivity and systematic effects of the method. The preliminary result of this experiment is dn = (2.5 ± 6.5) · 10 −24 e·cm. The performance was essentially limited by the low luminosity of the prototype setup. With a dedicated setup and a large quartz crystal, the expected accuracy is ∼ 2 · 10 −26 e·cm for 100 days of data collection.

An experiment searching for the neutron electric dipole moment by measuring spin-rotations in a non-centrosymmetric crystal was carried out to investigate the statistical sensitivity and systematic effects of the method. The preliminary result of this experiment is dn = (2.5 ± 6.5) · 10 −24 e·cm. The performance was essentially limited by the low luminosity of the prototype setup. With a dedicated setup and a large quartz crystal, the expected accuracy is ∼ 2 · 10 −26 e·cm for 100 days of data collection.

An experiment using a prototype setup to search for the neutron  moment by measuring spin rotation in a non-centrosymmetric crystal (quartz) was carried out to investigate statistical sensitivity and systematic effects of the method. It has been demonstrated that the concept of the method works. The preliminary result of the experiment is dn=0.25±6.5x10-24 e.cm. The experiment showed that an accuracy of  ~2.5x10-26 e.cm can be obtained in 100 days data taking, using available quartz crystals and neutron beams.

We present a first principles molecular dynamics study of water at the supercritical conditions T=647 K and ρ=0.322 g/cm3. At these conditions, the H-bonds are continuously broken and reformed in a dynamical fashion. We analyze the peculiar H-bond environment in terms of molecular configurations and dipole moment distribution. The latter shows that on average about half of the molecules still keep their gas phase character, not forming any H-bond, while the others cluster mostly in dimer and trimer configurations.

The dipole moments, angular momenta and gyromagnetic ratios of the electron and the proton were obtained earlier. In this note, we derive the corresponding expressions for the neutron and the muon. This work relies on the results obtained earlier for the angular momenta and dipole moments of rotating spherical bodies.

The electric dipole moments of the isolated amino acid tryptophan and small glycine-based peptides (WGn, n = 1−5, W = tryptophan, G = glycine) have been measured by deflection of a molecular beam in an inhomogeneous electric field. The measurements are compared to the results of ab initio calculations and Monte-Carlo simulations. The conformation and the flexibility of the peptides, at different temperatures, are discussed. The WGn peptides are much more floppy than an isolated tryptophan, even a single glycine is enough to make the peptide floppy on the timescale of the electric deflection measurements.

In proposals for quantum computers using arrays of trapped ultracold polar molecules as qubits, a strong external field with appreciable gradient is imposed in order to prevent quenching of the dipole moments by rotation and to distinguish among the qubit sites. That field induces the molecular dipoles to undergo pendular oscillations, which markedly affect the qubit states and the dipole-dipole interaction. We evaluate

The influence of a random field induced by impurities, boundary irregularities etc. on the superfluidity of a quasi-two-dimensional (2D) system of spatially indirect excitons in coupled quantum wells is studied. The interaction between excitons is taken into account in the ladder approximation. The random field is allowed to be large compared to the dipole-dipole repulsion between excitons. The coherent potential approximation (CPA) allows us to derive the exciton Green's function for a wide range of the random field, and the CPA results are used in the weak-scattering limit, which results in the second-order Born approximation. The Green's function of the collective excitations for the cases of (1) equal electron and hole masses and (2) the "heavy hole" limit are derived analytically. For quasi-two-dimensional excitonic systems, the density of the superfluid component and the Kosterlitz-Thouless temperature of the superfluid phase transition are obtained, and are found to decrease as the random field increases. This puts constraints on the experimental efforts to observe excitonic superfluidity.

We propose that the CP violating phase in the CKM mixing matrix is identical to the CP phases responsible for the spontaneous CP violation in the Higgs potential. A specific multi-Higgs model with Peccei-Quinn (PQ) symmetry is constructed to realize this idea. The CP violating phase does not vanish when all Higgs masses become large. There are flavor changing neutral current (FCNC) interactions mediated by neutral Higgs bosons at the tree level. However, unlike general multi-Higgs models, the FCNC Yukawa couplings are fixed in terms of the quark masses and CKM mixing angles. Implications for meson-anti-meson mixing, including recent data on D −D mixing, and neutron electric dipole moment (EDM) are studied. We find that the neutral Higgs boson masses can be at the order of one hundred GeV. The neutron EDM can be close to the present experimental upper bound.

We have performed quantum chemical calculations for coupled oscillations examining CO adsorbed on Cu(1 1 0) and atomic oxygen on the (1 0 0) diamond face. For CO, we find that our calculations show coupling consistent with a dynamic dipole-dipole interaction. In the case of the adsorbed oxygen atoms the dominant coupling seems to be mechanical. The limits of the semiempirical method SAM1 are tested for consistency and precision. Our model gives accuracy within 10% when compared to experiment and works well with near neighbor adsorbates.

The electric field pulses used for most measurements of transient electrooptic properties such as birefringence and dichroism, are rectangular and assumed to be ideal, but in practice do all such pulses have non-zero rise and fall times. Claims have been made that this non-ideality may be taken into account by employing standard deconvolution techniques. We find that this approach yields exact results in the zero electric field limit when the electric dipole moment of the studied macromolecules is predominantly induced. However, for finite electric field strengths and / or macromolecules with partly or fully permanent electric dipole moments, we find that the deconvolution method yields erroneous estimates of the electrooptic relaxation times. When the decay time of the electric pulse and the electrooptic decay time are equal, and the system is operated in the Kerr domain, this systematic error for macromolecules with purely permanent electric dipole moment equals 37%. In a research field where the uncertainty of the reported relaxation times normally is assumed to be only a few percent this is an error that may seriously mislead unsuspecting users. We find that this systematic error can readily be avoided by employing standard numerical integration of a set of coupled first-order differential equations instead of the standard deconvolution techniques.

A model of polar fluid is studied theoretically. The interaction potential, in addition to dipoledipole term, possesses a dispersion contribution of the van der Waals-London form. It is found that when the dispersion force is comparable to dipole-dipole interaction, the fluid separates into coexisting liquid and gas phases. The calculated critical parameters are in excellent agreement with Monte Carlo simulations. When the strength of dispersion attraction is bellow critical, no phase separation is found.

We propose the Bose-Einstein condensation (BEC) and superfluidity of quasi-two-dimensional (2D) spatially indirect magnetobiexcitons in a slab of superlattice with alternating electron and hole layers consisting from the semiconducting quantum wells (QWs) and graphene superlattice in high magnetic field. The two different Hamiltonians of a dilute gas of magnetoexcitons with a dipole-dipole repulsion in superlattices consisting of both QWs and graphene layers in the limit of high magnetic field have been reduced to one effective Hamiltonian a dilute gas of two-dimensional excitons without magnetic field. Moreover, for N excitons we have reduced the problem of 2N × 2 dimensional space onto the problem of N × 2 dimensional space by integrating over the coordinates of the relative motion of an electron (e) and a hole (h). The instability of the ground state of the system of interacting two-dimensional indirect magnetoexcitons in a slab of superlattice with alternating electron and hole layers in high magnetic field is established. The stable system of indirect quasi-two-dimensional magnetobiexcitons, consisting of pair of indirect excitons with opposite dipole moments is considered. The density of superfluid component ns(T) and the temperature of the Kosterlitz-Thouless phase transition to the superfluid state in the system of two-dimensional indirect magnetobiexcitons, interacting as electrical quadrupoles, are obtained for both QW and graphene realizations.

The efficiency of fluorescence resonance en- ergy transfer (FRET) between fluorescein and rhodamine covalently attached to both 5' termini of a series of double- stranded DNA species (ranging from 8 to 20 bp) was measured. FRET efficiency varied with a dependence compatible with dye-to-dye distances (R) calculated on the basis of double- stranded B-DNA structure; the helical geometry of double- stranded DNA in solution is clearly evident. The experimental data were consistent with a 1/[1 + (RIRo)6] dependence of FRET efficiency characteristic for the Forster dipole-dipole mechanism. The thermal dissociation of the strands of the duplex DNA species can be followed by using FRET, and from these data we have been able to obtain enthalpies of duplex formation in good agreement with earlier measurements using alternative techniques. FRET measurements at very different salt concentrations can be accurately compared. We conclude that FRET is a reliable and valuable method for studying structure and conformational transitions in nucleic acids.

A 2D Electrical Resistivity Tomography (ERT) survey was carried out in the tectonically active Tyrnavos Basin, Eastern Thessaly, Greece. The principal aims of this research are to test the efficiency of this relatively new geoelectrical technique when applied to the recognition and the geometrical characterisation of active faults and to improve our tectonic knowledge of the investigated area. We therefore carried out several tests performing the geophysical prospecting across morphotectonic scarps or fault traces along which the Late Quaternary tectonic activity is well documented by previous structural, stratigraphic, morphotectonic and palaeoseismological researches. The tests concerned the electrode spacing, the maximum depth of investigation, the quality-to-costs ratio, etc. In a second phase of the survey, we applied this geophysical methodology to specific sites along the major tectonic structures bordering the Tyrnavos Basin, in order to obtain, firstly, a better tectonic knowledge of the area, secondly, to solve particular and local geological problems and, thirdly, to help deciding between ambiguities left unsolved by superficial surveys. Accordingly, numerous ERT with different electrode spacing (from 2 up to 50 m) and depth of investigation (from 0.5 to 120 m) were performed with a dipole-dipole array using a multielectrode system, with 32 electrodes equally spaced along a straight line, for data acquisition. Combining advanced technologies for data acquisition and new tomographic techniques for resistivity data inversion, we obtain a large data-set of high-resolution electrical images of the subsurface across active faults. General and particular results concerning the application of ERT techniques for mapping subsurface active faults are discussed, while advantages and limits in applying this geophysical methodology are emphasised. #

The origin of most of the electron paramagnetic resonances obtained at low temperature and low microwave power from heart tissue and subcellular fractions derived therefrom is now understood. A signal that emerges on partial reduction with characteristic lines at 3227 G (0.3227 tesla) and 3309 G (0.3309 tesla) (at 9.2 GHz) and disappears again on full reduction has remained unidentified. According to its behavior on oxidation-reduction, the substance giving rise to this signal has the properties of a two-electron acceptor. The signal is strongly dependent on temperature and can only be well resolved at <20°K. It is readily elicited in submitochondrial particles by partial reduction, but has not been observed in submitochondrial particles from which ubiquinone has been removed by pentane extraction. When ubiquinone is reincorporated into extracted submitochondrial particles, the signal is again easily produced by partial reduction. Electron paramagnetic resonance spectra of partially reduced submitochondrial particles recorded at 34 GHz show lines centered about g 2 with the same separation (-82 G; -0.0082 tesla) as do 9.2 GHz spectra, whereas no lines are detected with a separation of approximately 82 X 34/9.2 G (0.0082 X 3419.2 tesla). We suggest, on the basis of these observations, that the unidentified signal arises from an interaction of ubisemiquinone and a second paramagnetic species. Three obvious choices exist concerning this second species: ubisemiquinone, flavin semiquinone, or an iron-sulfur center. It is not possible without much additional information to decide between these possibilities. Since we have never observed the signal in the absence of the membranebound, high-potential type iron-sulfur protein, we have con-

New Gibbs ensemble simulation data for a polar fluid modeled by a square-well potential plus dipoledipole, dipole-quadrupole, and quadrupole-quadrupole interactions are presented. This simulation data is used in order to assess the applicability of the multipolar square-well perturbation theory [A. L. Benavides, Y. Guevara, and F. del Río, Physica A 202, 420 (1994)] to systems where more than one term in the multipole expansion is relevant. It is found that this theory is able to reproduce qualitatively well the vapor-liquid phase diagram for different multipolar moment strengths, corresponding to typical values of real molecules, except in the critical region. Hence, this theory is used to model the behavior of substances with multiple chemical bonds such as carbon monoxide and nitrous oxide and we found that with a suitable choice of the values of the intermolecular parameters, the vapor-liquid equilibrium of these species is adequately estimated.

This paper describes a non-invasive method for detecting leaks in buried pipes, which uses a surface linear electrode array perpendicular to the axis of the pipe. Two electrodes inject current and the remaining electrodes detect the drop in voltage on the ground surface using both the dipole-dipole array and a modified Schlumberger array. A single-step reconstruction algorithm based on the sensitivity theorem yields two-dimensional images of the cross section. A personal computer controls current injection, electrode switching and voltage detection, which allows us to easily test various arrays of electrodes and speed up the process of measurement. The system was first tested in the laboratory using a stainless steel tube immersed in water and covered by a rubber sleeve to simulate a non-conductive leak. By taking reference measurements with the immersed bare pipe, it is possible to reconstruct images showing the simulated leak using only 16 electrodes and even as few as eight electrodes, albeit with reduced resolution. Field measurements have involved simulated leaks of water from a plastic tube 1 m long and 8 cm in radius buried at a depth of about 24 cm in a farm field. The hardware system injected 1 kHz, 20 V peak-to-valley square waveforms, thus avoiding electrode polarization effects. The simulated leak was unmistakably distinguished.

We derive an expression for direct non-radiative electronic energy transfer which accommodates the possibility of a distribution of donor environments. At present we deal with situations in which the sample has a plane of symmetry for the concentration profiles. The relation enables one to evaluate donor fluorescence decay functions lD(t) from a knowledge of donor/acceptor concentration profiles, CD(Z) and CA(Z), along the sample axis z. It reduces to known expressions in the case of DET in infinite media, and allows simplified asymptotic solutions or facile numerical analysis in systems with more complicated concentration profiles.

We propose a very sensitive method for measuring the electric dipole moment of the electron using polar molecules embedded in a cryogenic solid matrix of inert-gas atoms. The polar molecules can be oriented in theẑ-direction by an applied electric field, as has recently been demonstrated by Park et al. The trapped molecules are prepared into a state that has its electron spin perpendicular tô z, and a magnetic field alongẑ causes precession of this spin. An electron electric dipole moment d e would affect this precession due to the up to 100 GV/cm effective electric field produced by the polar molecule. The large number of polar molecules that can be embedded in a matrix, along with the expected long coherence times for the precession, allows for the possibility of measuring d e to an accuracy that surpasses current measurements by many orders of magnitude. Because the matrix can inhibit molecular rotations and lock the orientation of the polar molecules, it may not be necessary to have an electric field present during the precession. The proposed technique can be applied using a variety of polar molecules and inert gases, which, along with other experimental variables, should allow for careful study of systematic uncertainties in the measurement.