Papers by Karl-Heinz Gericke
Book Review: State Selected and State-to-State Ion–Molecule Reaction Dynamics. Part 1: Experiment, Part 2: Theory.(Series: Advances in Chemical Physics, Vol. 82.) Edited by C.-Y. Ng and M. Baer
Angewandte Chemie, Mar 1, 1993
Macromolecular Bioscience, Dec 17, 2012
State-to-state studies of ground state NH(X 3Σ−,v=0,J,N)+Ne
Journal of Chemical Physics, Oct 15, 2000
State-to-state rotational energy transfer of ground state NH(X 3Σ,v=0,J,N) in collisions with Ne ... more State-to-state rotational energy transfer of ground state NH(X 3Σ,v=0,J,N) in collisions with Ne is examined. NH is exclusively generated in the metastable NH(a 1Δ) state via photodissociation of hydrazoic acid at a wavelength of 266 nm. The strongly forbidden NH(a 1Δ→X 3Σ−) intercombination transition around 794 nm is used to generate single state NH(X 3Σ−,v=0,J,N) applying the stimulated emission pumping technique. The ground state radicals are detected after a certain delay time with laser induced fluorescence (LIF) using the intense NH(A 3Π←X 3Σ−) transition around 336 nm with respect to all quantum states. The collision induced energy flux between the different rotation and spin levels is studied in detail and a comprehensive set of state-to-state rate constants for inelastic collisions of NH(X 3Σ−,v=0,J,N) with Ne up to N=7 which include the effect of multiple collisions is given. The state-to-state rate constants are obtained by the use of an iterative integrated profiles method. We find a propensity for (ΔN=0, Δi=±1) and (ΔN=±1, Δi=0) transitions where N represents the quantum state for nuclear rotation and i represents the index of the spin component Fi. In most cases the energy transfer which changes the spin component and conserves the nuclear rotation quantum number N (ΔN=0, Δi=±1), is the most effective energy transfer in collisions with Ne. The energy dependence of the transition efficiency concerning only the nuclear rotation quantum number N obeys an energy-gap law (EGL).
State-to-state energy transfer of NH(X 3Σ−,v=0,J,N) in collisions with He and N2
Journal of Chemical Physics, May 22, 2002
State-to-state rotational energy transfer of ground state NH(X 3Σ−,v=0,J,N) in collisions with He... more State-to-state rotational energy transfer of ground state NH(X 3Σ−,v=0,J,N) in collisions with He and N2 is studied. A complete inversion between the metastable NH(a 1Δ) state and the NH(X 3Σ−) state is generated via the photodissociation of hydrazoic acid at a wavelength of 266 nm. Single state NH(X 3Σ−,v=0,J,N) is generated by applying the stimulated emission pumping technique using the strongly forbidden NH(a 1Δ→X 3Σ−) intercombination transition around 794 nm. The ground state NH(X 3Σ−,v=0,J,N) distribution is probed with respect to all quantum states using laser induced fluorescence varying delay times and pressures. The collision induced energy transfer between the different rotational and spin levels is extensively studied and two comprehensive sets of rate constants for vibrationally elastic and rotationally inelastic collisions with He and N2 as collision partners are given which include the effect of multiple collisions. We find propensities for (ΔN=0,Δi=±1) and (ΔN=±1,Δi=0) transitions where N represents the quantum state for nuclear rotation and i represents the index of the spin component Fi. The rotational relaxation for N2 as a collision partner occurs on the average three times faster than the rotational relaxation with He as a collision partner. The energy dependence of the transition efficiency for only the nuclear rotational quantum number N obeys an energy-gap law for both He and N2.
ChemPhysChem, Jul 13, 2009
Journal of Fluorescence, Sep 6, 2011
The analysis of autofluorescence, often regarded as undesired noise during the imaging of biologi... more The analysis of autofluorescence, often regarded as undesired noise during the imaging of biological samples, allows label free, unbiased detection of NAD(P)H and melanin in native samples. Because both the emission and absorption spectra of these fluorophores overlap and they can hence not be differentiated using emission filters or with different excitation wavelengths, fluorescence lifetime imaging microscopy (FLIM) is used to differentiate between them. In the present paper the application of two-photon excitation microscopy is presented to investigate the autofluorescence of fungal spores. The model organism which was examined is Aspergillus ochraceus. Furthermore a strategy is developed which allows to quantitatively analyze the fluorescence lifetimes of melanin, free NAD(P)H and protein-bound NAD(P)H using forward convolution of a multiexponential decay function with the instrument response function (IRF) and subsequent fitting to the experimental fluorescence data. As a consequence proteins, which are able to bind NAD(P) H, are located with sub-cellular resolution. Furthermore a spatial differentiation of the fluorophores NAD(P)H and melanin inside the spores, is revealed.
Journal of Molecular Spectroscopy, Nov 1, 1999
A completely resolved spectrum of the strongly forbidden NH (a 1 ⌬ 3 X 3 ⌺ Ϫ ) transition is obse... more A completely resolved spectrum of the strongly forbidden NH (a 1 ⌬ 3 X 3 ⌺ Ϫ ) transition is observed. The NH radicals in the excited a 1 ⌬ state are exclusively generated in a Nd:YAG laser photolysis of hydrazoic acid at a wavelength of 266 nm. The NH (a 1 ⌬ 3 X 3 ⌺ Ϫ ) intercombination transition around 794 nm is used to produce NH (X 3 ⌺ Ϫ ) applying the stimulated emission pumping technique. The ground state radicals are detected by laser-induced fluorescence (LIF). The energy splitting between the NH (X 3 ⌺ Ϫ , v ϭ 0, J ϭ 1, N ϭ 0) state and the NH (a 1 ⌬, v ϭ 0, J ϭ 2) state is determined with an accuracy of 0.1 cm Ϫ1 to ⌬E ϭ 12 687.8 65 cm Ϫ1 . In addition, the radiative lifetime of the NH (a 1 ⌬ 3 X 3 ⌺ Ϫ ) transition was estimated by a determination of the saturation intensity to be Ϸ 12.5 s.
Control of Ion–Molecule Reactions in the Gas Phase
Angewandte Chemie, May 2, 1995
Physical Review Letters, Feb 15, 1988
A new method has been developed for determining the correlation of a product molecule with the pa... more A new method has been developed for determining the correlation of a product molecule with the partner product molecule formed in the same chemical event. Doppler-shift measurements are used in conjunction with level-specific detection of scattered photofragments by laser-induced fluorescence. The technique is demonstrated in the photodissociation of H202 where Doppler profiles of OH absorption lines are used to determine the mean rotational state of the OH partner molecule coincidently formed in the same fragmentation process.
Biophysical Journal, 2010
High resolution FTIR study of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si0244.gif" overflow="scroll"><mml:msub><mml:mrow><mml:mi>ν</mml:mi></mml:mrow><mml:mrow><mml:mn>7</mml:mn></mml:mrow></mml:msub><mml:mo>+</mml:mo><mml:msub><mml:mrow><mml:mi>ν</mml:mi></mml:mrow><mm...
Journal of Quantitative Spectroscopy & Radiative Transfer, Dec 1, 2014
ABSTRACT Two weak “hot” absorption bands, ν7+ν10−ν10ν7+ν10−ν10 and ν10+ν12−ν10ν10+ν12−ν10, of eth... more ABSTRACT Two weak “hot” absorption bands, ν7+ν10−ν10ν7+ν10−ν10 and ν10+ν12−ν10ν10+ν12−ν10, of ethylene, C2H4, were analyzed for the first time with high resolution using the Fourier transform interferometer Bruker IFS-120 HR. As the result of analysis we assigned about 930 and 370 transitions (404 and 185 upper state ro-vibrational energy values) with Jmax.=27Jmax.=27, Kamax.=14 and Jmax.=20Jmax.=20, Kamax.=9 for the bands ν7+ν10−ν10ν7+ν10−ν10 and ν10+ν12−ν10ν10+ν12−ν10, respectively. Strong local resonance interactions of the vibrational state (v10=v12=1)(v10=v12=1) with the five other states, and of the state (v7=v10=1)(v7=v10=1) with the seven other states were taken into account, and a set of 77 varied parameters, which reproduce the initial experimental data with the rms deviation of 6.1×10−4 cm−1 which is close to experimental uncertainties, was obtained.
A process for producing a plasma, and using a plasma so produced
The invention relates to a process for preparing a plasma in which the plasma is produced by inte... more The invention relates to a process for preparing a plasma in which the plasma is produced by interaction of free electrons with other particles. The plasma is produced in the form of a plasma sheet while free electrons with an electrical field intensity of this kind are produced, said plasma sheet being produced by cold emission without special ambient conditions such as high temperature from a solid structure, in particular metal. The electrical field intensity causing the emission is set up by the geometry of the electrode structure, in particular for electrode structures of several nm to mm, to be locally limited. Many locally limited electrical fields are attached to each other substantially in one plane.
State‐to‐state reaction dynamics of R+HCN (ν<sub>1</sub>ν<sup><i>l</i><sub>2</sub></sup><sub>2</sub>ν<sub>3</sub>)→RH+CN(<i>v</i>, <i>J</i>) with R=Cl, H
Journal of Chemical Physics, Mar 22, 1996
Vibrational overtone excitation of HCN in the wavelength region 6 500 cm−1–18 000 cm−1 is used to... more Vibrational overtone excitation of HCN in the wavelength region 6 500 cm−1–18 000 cm−1 is used to initiate the endothermic reaction of chlorine and hydrogen atoms with HCN. HCN is excited to the overtone levels (002), (004), (302), (105), and (1115). The labeling of the vibrational levels (ν1ν2l2ν3) corresponds to the normal modes ν1=CN, ν2=bend, ν3=CH, and l2=vibrational angular momentum. The product state distribution of CN(X 2Σ+) is completely analyzed by laser induced fluorescence (LIF). Excitation of the first overtone of CH-stretch leads to vibrationally excited CN in the reaction of Cl+HCN(002), implying the existence of a long living complex. The CN vibrational excitation increases with increasing H–CN stretch excitation. However, a slightly higher CN vibrational excitation is found when at the same internal energy of HCN three quanta of CN-stretch and two quanta of CH-stretch are excited. Therefore, the energy is not completely redistributed in the collision complex. The ratio of rate constants between the reactions of HCN(004) and HCN(302) with Cl is 2.8±0.6. The CN product vibrational excitation decreases again, when HCN is excited to the (105) state. At these high HCN vibrational energies the reaction mechanism seems to change toward a more direct reaction where the time left is not sufficient for energy randomization. The reaction of hydrogen with HCN(004) leads to CN-products with a similar vibrational distribution, as in the case of chlorine, but with a lower rotational excitation. The reaction H+HCN(302) shows no significant generation of CN products and a lower limit of the ratio of rate constants, k(004)/k(302)≳4, is obtained.
ChemPhysChem, May 17, 2002
We report a novel approach to micro-and nanoparticle rotation, uniting the fine translational con... more We report a novel approach to micro-and nanoparticle rotation, uniting the fine translational control afforded by optical trapping with the flexibility and simplicity of dipole ± field-induced coupled electrorotation (CER). Fluorescence imaging using a microparticle photopatterning technique was combined with optical trapping to quantify both the senses and speeds of rotation for individual pairs of particles. Laser tweezers allowed controlled positioning of a pair of particles within a dipole field while simultaneously providing an axis about which the particles rotated. The particle ± particle interactions inherent in CER offer several distinct advantages compared with electrorotation in multipole fields. Results from several investigations highlight the utility of this approach, including quantification of rotation in spheres as small as 750 nm in diameter, observation of rotation rates as high as 1800 rpm, fabrication of coupled electrorotational ∫antigears∫, trapping and rotation of sphere dimers, and exploitation of the registry of sphere rotation to probe the dielectric properties of immobile objects.
Angewandte Chemie, Apr 13, 1995
Chemical Engineering Journal, Aug 1, 2004
A microreactor based on a micro-structured electrode (MSE) system is presented. With radio freque... more A microreactor based on a micro-structured electrode (MSE) system is presented. With radio frequency electric power applied to the interdigitated, comb-like capacitor structure a homogeneous plasma is driven at atmospheric pressure with low ignition voltages due to small electrode gaps. The MSE is micromachined by plating nickel onto alumina ceramics. A micromachined Foturan ® structure with inlet and outlet channels for the gas flow serves as a reaction chamber. The design of the reactor cell is arranged in a 4 × 4-array in a multireactor system. The performance of the reactor is modeled with computational fluid dynamics (CFD), used to improve the reactor design. Experiments show that CF 4 decomposition rates of over 70% can be achieved at atmospheric pressure.
Plasma Processes and Polymers, Mar 31, 2005
Journal of Chemical Physics, Dec 1, 1994
The dynamics of the reaction OH('II)+HCN+CN("Z)+H20 has been investigated at different collision ... more The dynamics of the reaction OH('II)+HCN+CN("Z)+H20 has been investigated at different collision energies between 55.7 and 109.5 kJ/mol with the laser pump-and-probe technique. CN is formed in its electronic and vibrational ground state. Product rotational state distributions and line profiles have been obtained. We determined the partition of the available energy to the degrees of freedom of the products. At low collision energies most of the energy is released as translation, while at high collision energies the internal excitation of the newly formed Hz0 molecule dominates the energy balance. The fraction of CN rotational energy remains nearly constant. The effective transfer of reactant translation to product internal excitation indicates that the reaction surmounts an early barrier. Further, absolute reaction cross sections have been determined at two collision energies. 0 1994 American institute of Physics.
Chemical Physics, Sep 1, 1993
The q&num state resolved product state distribution of the reactions 0('D)+H2(u=0, l)+OH(Q v, J, ... more The q&num state resolved product state distribution of the reactions 0('D)+H2(u=0, l)+OH(Q v, J, Q, A)+H and C("D)i-H*(u=O, l)-t~(Zn,u,J,qn)+awmanalysedbylaser-induc+dfl~~. For studying the irhence of vibrational excitation on the reaction dynamics, Hz was excited to its fort v&rational state via stimulated Raman pumpink For both reactions H2 (o= 1) increases the reaction rate, but diminishes the A selectivity. Insertkm of the atomic collision psrtner into the H2 bond is the major reaction mechanism, but the probability for an &traction pmcees seean to increase when Hz is vibrationally excited. The ~IIGWUCC of translational energy on the reaction dynamics is observed for &uct states near the energetical Ii&t. InthecaseofO('D)+H~asignificants,~~nenergyig tran&hd into OH rot&on, while the reaction ofC('D)+H1 transfers translational energy into vibrationally excited CH products.
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Papers by Karl-Heinz Gericke