Showing papers on "Photoexcitation published in 1999"
TL;DR: In this paper, the electrostatic properties of individual CdSe nanocrystals were directly measured using electrostatic force microscopy (EFM) in dry air at room temperature.
Abstract: The electrostatic properties of individual CdSe nanocrystals are directly measured using electrostatic force microscopy (EFM) in dry air at room temperature. We determine that the static dielectric constant of CdSe nanocrystals with diameters 5 nm is uniform. However, the charge per nanocrystal is nonuniform, with some nanocrystals possessing a positive charge. Furthermore, a small fraction of the nanocrystals exhibit a blinking behavior in their charge. This is entirely unexpected for a dielectric particle with no additional charge carriers. In addition, EFM measurements with simultaneous photoexcitation provide direct evidence of nanocrystal photoionization and increased blinking behavior.
277 citations
TL;DR: In this article, the coupling mechanism between an intense (∼1013 W cm-2, 780 nm) near-infrared radiation field of duration 50−200 fs with molecules having 5−50 atoms is considered.
Abstract: The coupling mechanism between an intense (∼1013 W cm-2, 780 nm) near-infrared radiation field of duration 50−200 fs with molecules having 5−50 atoms is considered in this article. In general, the interaction of intense radiation fields with molecules can result in both electron emission and subsequent dissociation. For the laser excitation scheme employed here, intact ions are observed in addition to dissociative ionization channels for all classes of molecules investigated to date. An excitation mechanism is considered where the electric field of the laser mediates the coupling between the radiation and the molecule. This field-induced ionization is compared with the more common frequency-mediated coupling mechanism found in multiphoton processes. Measurements of intense-laser photoionization probability are presented for several series of molecules. An outline of our structure-based model is presented to enable calculation of relative tunneling rates and prediction of the laser−molecule coupling mechan...
134 citations
TL;DR: In this article, the energy dependence of the antibonding state population dynamics is consistent with Cs photodesorption, and femtosecond resolution pump-probe correlation measurements indicate phase and energy decay, respectively, on 15 and 50 fs time scales for the Cs/Cu(111) surface at 33 K.
Abstract: Electron dynamics induced by direct photoexcitation of the antibonding state on the Cs/Cu(111) surface are studied by interferometric time-resolved two-photon photoemission. Femtosecond resolution pump-probe correlation measurements indicate phase and energy decay, respectively, on 15 and 50 fs time scales for the Cs antibonding state at 33 K. Both the polarization and phase dynamics are nonexponential and strongly temperature dependent. The energy dependence of the antibonding state population dynamics is consistent with Cs photodesorption.
109 citations
TL;DR: In this paper, the authors used dispersed fluorescence scans of the A-X(4,v") and D-X (0,v) progressions of nitric oxide, after two-photon excitation, to determine the electronic transition moments of these band systems.
Abstract: Dispersed fluorescence scans of the A–X(4,v″) and D–X(0,v″) progressions of nitric oxide, after two-photon excitation, are used to determine the electronic transition moments of these band systems. The measured collision free lifetimes of 206±7 ns for A 2Σ+, v′=0, and 18±1 ns for D 2Σ+, v′=0 are used to place transition probabilities on an absolute basis. The branching ratio for D→X is 3.0±0.3 times that for D→A and more than 30 times that for D→C. The ratio of two-photon absorption cross sections for D–X(0,0)/A–X(4,0) is 6±2 and the photoionization probability from D, v′=0 is larger than from A, v′=4 at 375 nm. Also, the two-photon excitation of A–X(4,0) has an unusual intensity distribution, probably due either to interference between intermediate states in the excitation or to anomalies in the photoionization step.
107 citations
TL;DR: For p-benzoquinone anions, the photodetachment spectrum at 0.15-0.65 eV above detachment threshold shows sharp and broad resonances, which are assigned to enhanced photodeteachment via resonantly excited anion states as mentioned in this paper.
Abstract: For p-benzoquinone anions, the photodetachment spectrum at 0.15–0.65 eV above detachment threshold shows sharp and broad resonances, which we assign to enhanced photodetachment via resonantly excited anion states. The experiment is performed at cold and mass-selected anions to exclude contributions of fragment anions and internally excited molecules. The most prominent, intense and broad spectral feature at 20 200 cm−1 is assigned to an allowed transition from the 2B2g anion ground state to the 2Au shape resonance, which corresponds to a πLUMO*→π* electron promotion. By linewidth we determine an ultrashort lifetime of 25 fs in qualitative agreement with a one-electron autodetachment process. In contrast to this, for the narrow resonances lifetimes between 0.2 and 1.2 ps are determined, in agreement with a slower autodetachment by a two-electron process from Feshbach states. Because of their low photoexcitation cross section they are assigned to dipole and symmetry forbidden n→πLUMO* transitions which can ...
102 citations
TL;DR: In this paper, a femtosecond laser pulse at 260 nm was used to characterize the excited state absorption of neutral indole molecules in 1-propanol where photoexcitation at 260nm does not lead to photoionization.
Abstract: Indole in aqueous solution is photoionized near threshold following single photon absorption from a femtosecond laser pulse at 260 nm. Transient absorption measurements are performed using a white-light continuum probe pulse. Excited state absorption of neutral indole molecules is characterized accurately in 1-propanol where photoexcitation at 260 nm does not lead to photoionization. The presence of 0.75 M carbon tetrachloride in a solution of indole/1-propanol leads to the formation of indole radical cations on a picosecond time scale. While solvated electrons are formed in aqueous indole within our time resolution of 200 fs, measurements of the transient absorbance out to 100 ps are flat and indicate that geminate recombination is insignificant on this time scale. This result contrasts sharply with the geminate recombination dynamics observed following the photoionization of neat water. This indicates that the bimolecular reaction between indole radical cations and solvated electrons is considerably slo...
101 citations
TL;DR: In this article, the authors investigated the early relaxation dynamics of the equilibrated hydrated electron within the first 200 fs upon photoexcitation using photon echo techniques and showed that even for extremely short pulse durations, the signals obtained in photon echo spectroscopy can be described in the conventional way, provided care is taken of the spectral filtering effect and experimental beam arrangement.
Abstract: Employing photon echo techniques, we investigate the early relaxation dynamics of the equilibrated hydrated electron within the first 200 fs upon photoexcitation. The use of 5-fs laser pulses provided unprecedented temporal resolution of our measurements. We show that even for extremely short pulse durations the signals obtained in photon echo spectroscopy, can be described in the conventional way, provided care is taken of the spectral filtering effect and experimental beam arrangement. We next conclude that the absorption spectrum of the hydrated electrons is primarily homogeneously broadened. The comparison of two pulse photon echo experiments on pure water and on hydrated electrons allows us to measure the pure dephasing time of ∼1.6 fs. The line shape of the absorption spectrum is described excellently by an extended Lorentzian contour with a spectral width fully determined by the pure dephasing time. From the polarization-dependent transient grating experiments we establish that the polarization ani...
78 citations
TL;DR: In this article, a femtosecond probe spectroscopy in the spectral range between 580 nm and 990 nm was used to obtain the absorption bands of the solvated electron after 2 eV visible pulses and showed that the second intermediate in the UV-excitation experiment is identical to the modified ground state s″ occupied after excitation in the visible.
Abstract: We report on a novel investigation of the solvated electron with excitation into the continuum band. The subsequent localization process of quasifree electrons in neat water is studied by femtosecond probe spectroscopy in the spectral range between 580 nm and 990 nm. Excitation is achieved by a pump pulse at 310 nm promoting equilibrated solvated electrons to well-defined levels in the continuum band approximately 0.7 eV above the band edge. The subsequent retrapping and solvation of the electron occurs via two observed intermediates with time constants of τ2=300±50 fs and τs=1.0±0.2 ps. The absorption bands of the two intermediates are derived by the help of a 4-level energy scheme. Comparison with investigations of the solvated electron after excitation with 2 eV visible pulses gives strong evidence that the second intermediate in the UV-excitation experiment is identical to the modified ground state s″ occupied after excitation in the visible. The present study with excitation of the solvated electrons...
75 citations
TL;DR: In this article, the photoluminescence (PL) characteristics of pure nanoscale silicon quantum wires (SiQW's) were evaluated under ultraviolet photoexcitation.
Abstract: The recent success of bulk synthesis of pure nanoscale silicon quantum wires (SiQW's) enables us to evaluate their photoluminescence (PL) characteristics under ultraviolet photoexcitation. Intensive multiple light emissions ranging from dark red to blue regions were revealed for as-grown and partially oxidized SiQW samples. The red light emission was ascribed to a quantum confinement effect originating from the crystalline core of the SiQW's that is closely mediated by the interface. However, the PL emission from green to blue is found to be definitely unrelated to quantum confinement; instead they are attributed to the radiative recombination from defect centers in the overcoating layer of the amorphous silicon oxide outside the SiQW's.
73 citations
TL;DR: In this paper, a Zn-tetraphenyl porphyrin-fullerene complex is used for electron transfer with very long lifetimes of the charge-separated pairs.
69 citations
TL;DR: The molecular structural volume change (as determined by laser-induced optoacoustics), ΔVR ∼−18 A3, accompanying triplet state formation of free base 5,10,15,20-tetrakis-(4-sulfonatophenyl)-porphin...
Abstract: The molecular structural volume change (as determined by laser-induced optoacoustics), ΔVR ∼−18 A3, accompanying triplet state formation of free base 5,10,15,20-tetrakis-(4-sulfonatophenyl)-porphin...
TL;DR: In this article, a femtosecond time-resolved multiphoton ionization technique, coupled with a reflectron time-of-flight mass spectrometer, was used to measure the lifetime of d6-acetone.
Abstract: Because of the dispute in the literature over the dissociation rate and energy partitioning of the acetone molecule upon photoexcitation to the S1 state (π*←n) and 3s Rydberg state (3s←n), we have remeasured the lifetime of acetone (also d6-acetone) on the S1 and 3s surfaces by a femtosecond time-resolved multiphoton ionization technique, coupled with a reflectron time-of-flight mass spectrometer. The measured dissociation rate of acetone on the S1 surface is prompt, and the acetyl radical is long lived. The lifetime of acetone on the 3s surface is measured to be 3.2±0.4 ps (6.0±0.5 ps for d6-acetone). The dissociation rate of acetyl is approximately 1.7 ps (2.5 ps for d3-acetyl) from the curve fitting. This agrees well with the Rice–Ramsperger–Kassel–Marcus theory predicted lifetime of 1.0 ps (1.9 ps for d3-acetyl) when the internal excitation energy of the acetyl radical is treated by a statistical-adiabatic-impulsive model.
TL;DR: In this article, the photo-induced phase transition in tetrathiafulvalene-p-chloranil crystals is discussed. But the transition takes place only above a threshold intensity of excitation, and the efficiency of generating neutral-phase domains is lower than the case induced by the excitation in intramolecular optical transitions of tetrathylfvalene molecules.
Abstract: The transformation from ionic to neutral phases in tetrathiafulvalene-p-chloranil crystals is induced by exciting the charge-transfer absorption band below the transition temperature. The transformation takes place only above a threshold intensity of excitation, and the efficiency of generating neutral-phase domains is lower than the case induced by the excitation in intramolecular optical transitions of tetrathiafulvalene molecules. The mechanism of the photoinduced phase transition in this crystal is discussed based on these results.
TL;DR: In this paper, the formation of a vibrationally excited photoproduct of nickel octaethylporphyrin (NiOEP) upon (π, π*) excitation and its subsequent vibrational energy relaxation were monitored by picosecond time-resolved resonance Raman spectroscopy.
Abstract: The formation of a vibrationally excited photoproduct of nickel octaethylporphyrin (NiOEP) upon (π, π*) excitation and its subsequent vibrational energy relaxation were monitored by picosecond time-resolved resonance Raman spectroscopy. Stokes Raman bands due to the photoproduct instantaneously appeared upon the photoexcitation. Their intensities decayed with a time constant of ∼300 ps, which indicates electronic relaxation from the (d, d) excited state (B1g) to the ground state (A1g), being consistent with the results of transient absorption measurements by Holten and co-workers [D. Kim, C. Kirmaier, and D. Holten, Chem. Phys. 75, 305 (1983); J. Rodriguez and D. Holten, J. Chem. Phys. 91, 3525 (1989)]. The Raman frequencies of NiOEP in the (d, d) excited state are shifted to lower frequencies compared to those of the ground state species, and it is reasonably interpreted by the core size expansion of the macrocycle by 0.05 A upon the electron promotion from the dz2 to the dx2−y2 orbital. Anti-Stokes ν4 i...
TL;DR: In this paper, a self-consistent plasmachemical model describing the dynamics of the non-equilibrium microwave discharge in molecular nitrogen with consideration for kinetic, photochemical and electrodynamic phenomena is proposed.
Abstract: A self-consistent plasmachemical model describing the dynamics of the non-equilibrium microwave discharge in molecular nitrogen with consideration for kinetic, photochemical and electrodynamic phenomena is proposed. The photochemical block of the model accounts for the processes of photoexcitation and photoionization of nitrogen molecules in the ground and excited electronic states. Radiative emittance of the discharge plasma is conditioned by the processes of photorecombination of electrons and positive ions as well as by the processes of spontaneous radiation of electronically excited molecules. Solution of radiation transfer equations and calculation of photochemical constants were made with allowance for the vibrational-rotational structure of the corresponding radiative transitions. The calculations performed have shown that the velocities of the ionization front propagation in the microwave discharge that were observed experimentally may be explained without invoking considerations concerning the existence of easily ionizable admixtures in nitrogen. The phenomenon of electron generation in the photohalo region of the discharge is mainly conditioned by the processes of stepwise photoionization of nitrogen molecules. The mechanisms leading to the development of kinetic instabilities in the discharge region are analysed, and a satisfactory agreement between calculation and experimental results is noted.
TL;DR: In this article, photoluminescence data were used to conclusively establish that photoexcitation of substituted phenylenevinylene polymer films results in a large quantum yield of nearly nonluminescent interchain excitations at ambient temperatures.
TL;DR: In this paper, the authors discuss several mechanisms that could be responsible for nuclear excitation in a plasma of temperature of order 10-100 eV, including resonance transition from an excited bound state to a lower-lying bound state, electron capture from the continuum, photoexcitation, and inelastic electron scattering.
Abstract: This paper discusses several mechanisms that could be responsible for nuclear excitation in a plasma of temperature of order 10--100 eV. Four mechanisms discussed in detail are nuclear excitation by a resonant electronic transition from an excited bound state to a lower-lying bound state, nuclear excitation by electron capture from the continuum, photoexcitation, and inelastic electron scattering. Estimates of the rates for these different processes are presented for the excitation of ${}^{235m}\mathrm{U}$ for which the present experimental data lacks adequate theoretical interpretation.
TL;DR: In this article, the electronic and vibrational relaxation of tetracene have been studied in solution by femtosecond time-resolved fluorescence spectroscopy, and the lifetime was determined as ∼120 fs.
Abstract: The electronic and vibrational relaxation of tetracene have been studied in solution by femtosecond time-resolved fluorescence spectroscopy. Tetracene was initially photoexcited to the highly excited singlet (Sn) state, 1Bb, and the dynamics of the fluorescence from the 1Bb state and the 1La state (S1) were investigated by fluorescence up-conversion. The fluorescence from the 1Bb state was observed in the ultraviolet region, and its lifetime was determined as ∼120 fs. The anisotropy of the 1Bb fluorescence was close to 0.4, which assured that the fluorescence is emitted from the excited state that was prepared by photoexcitation. The visible fluorescence from the 1La state showed a finite rise that agreed well with the decay of the 1Bb fluorescence. Negative anisotropy was observed for the 1La fluorescence, reflecting that the 1La transition moment is parallel to the short axis of the molecule and hence perpendicular to the 1Bb transition moment. The anisotropy of the 1La fluorescence, however, showed a v...
TL;DR: In this paper, an experimental apparatus for surface reaction research has been designed as an end-station of a soft x-ray beamline, BL23SU, in the SPring-8.
Abstract: An experimental apparatus for surface reaction research has been designed as an end-station of a soft x-ray beamline, BL23SU, in the SPring-8. The soft x-ray with intense flux density is provided by a variable-polarizing undulator and is monochromized by using a varied line-spacing plane grating with grazing-incidence. A supersonic molecular beam technique is applied to obtain translational-energy control of incident molecules. Owing to keeping low pressure in the surface reaction chamber during molecular beam operation, the analysis of translational-energy-induced surface reactions is achieved by simultaneous application of the photoelectron spectroscopy. The end-station will promote research activities on new atomic layer reactions induced by the kinetic energy of incident molecules as well as new photofragmentation of monolayer due to the inner-shell selective photoexcitation.
TL;DR: In this article, the coupling of two large amplitude motions, the internal rotation of the methyl group and the intramolecular proton transfer, has been investigated for jet-cooled 5-methyltropolone, 5-mtolone-OD, and the 5-metallothiopolone−(H2O) 1:1 hydrogen-bonded complex by measuring the fluorescence excitation, dispersed fluorescence, and hole-burning spectra in the S1-S0 region.
Abstract: The coupling of two large amplitude motions, the internal rotation of the methyl group and the intramolecular proton transfer, has been investigated for jet-cooled 5-methyltropolone, 5-methyltropolone–OD, and the 5-methyltropolone–(H2O)1 1:1 hydrogen-bonded complex by measuring the fluorescence excitation, dispersed fluorescence, and hole-burning spectra in the S1–S0 region. The vibronic bands in the excitation spectrum of 5-methyltropolone consist of four components originating from the transitions between the sublevels in the S1 and S0 states. The intensity of the bands, the frequencies, and the change in the stable conformation of the methyl group upon photoexcitation have been analyzed for 5-methyltropolone–(H2O)1 by calculating the one-dimensional periodic potential function, which provides the correlation between the internal rotational levels of 5-methyltropolone–(H2O)1 and the sublevels of 5-methyltropolone. It has been shown that the electronic transitions between the sublevels within the same sy...
TL;DR: The title radicals were produced by femtosecond collisional electron transfer in the gas phase and studied by the methods of variable-time neutralization−reionization mass spectrometry combined with fast-beam laser photoexcitation and G2(MP2) ab initio/RRKM calculations.
Abstract: The title radicals were produced by femtosecond collisional electron transfer in the gas phase and studied by the methods of variable-time neutralization−reionization mass spectrometry combined with fast-beam laser photoexcitation and G2(MP2) ab initio/RRKM calculations. The methylsulfonyl radical (CH3SO2•, 1) was calculated to be bound by 59 kJ mol-1 against the lowest-energy dissociation to CH3• and SO2 at 0 K and to have a heat of formation ΔHf,298(1) = −211 ± 4 kJ mol-1. When formed by vertical electron transfer, radical 1 dissociated rapidly due to a large Franck−Condon energy, EFC = 141 kJ mol-1. The reverse addition of CH3• to the sulfur atom in SO2 had a potential energy barrier of 1.3 kJ mol-1 and Arrhenius parameters, log A = 12.19 and Ea = 5.4 kJ mol-1. The calculated addition rate constant, k295 = 1.7 × 1011 cm3 mol-1 s-1, was in excellent agreement with the previous measurement of Simons et al. The methoxysulfinyl radical (CH3OSO•, 2) was calculated to exist as an equilibrium mixture of syn (...
TL;DR: In this paper, the thermal ionization energies of traps and their types, whether electron or hole traps, were measured in commercial CdZnTe crystals for radiation detectors, and the measurements were done between 20 and 400K using thermoelectric emission spectroscopy (TEES) and thermally stimulated conductivity (TSC).
Abstract: The thermal ionization energies of traps and their types, whether electron or hole traps, were measured in commercial CdZnTe crystals for radiation detectors. The measurements were done between 20 and 400K using thermoelectric emission spectroscopy (TEES) and thermally stimulated conductivity (TSC). For reliable results, indium ohmic contacts had to be used instead of gold Schottky contacts. For filling of the traps, photoexcitation was done at zero bias, at 20K, and at wavelengths which gave the maximum bulk photoexcitation. In agreement with theory, the TSC current was found to be on the order of \( \sim \tfrac{{eV}}{{k\Delta T}}\) times or even larger than the TEES current, where V is the applied bias in TSC and ΔT is the applied temperature difference in TEES. Large concentrations of hole traps at 0.1 and 0.6 eV were observed and a smaller concentration of electron traps at 0.4 eV was seen. The deep traps cause compensation in the material, which is desirable, but they also cause carrier trapping that degrades the spectral response of radiation detectors made from the material.
TL;DR: In this article, a two-dimensional photoelectron imaging technique using time-of-flight spectrometry and a high-resolution SES-200 electron energy analyzer have been used with photons from the atomic and molecular undulator beamline of the Advanced Light Source to study the structure and dynamics of atoms and molecules.
TL;DR: In this paper, the orientation of pyrimidine in a strong electric field was measured using resonantly enhanced multiphoton ionization (REMPI) and laser induced fluorescence (LIF).
Abstract: Orientation of pyrimidine in a strong electric field was measured using resonantly enhanced multiphoton ionization (REMPI) and laser induced fluorescence (LIF). The ion and fluorescence yields showed preference for perpendicular excitation relative to the orientation field, implying a perpendicular relationship between the permanent dipole and the transition dipole. Calculation results using a linear variation method reproduced the observed spectral features, overall transition intensity, and polarization preference of the excitation laser. The permanent dipole of the S1 state of pyrimidine was thereby determined to be +0.6 Debye. Measurements of polarization preferences in photoexcitation, i.e., linear dichroism, provide a direct approach for determination of transition dipole moments. A general theory of deriving directions of transition dipoles relative to permanent dipoles based on this type of measurement/calculation was also developed. In addition, we report observations of complex relaxation dynami...
TL;DR: The femtosecond pump-probe measurements, both conventional and electric field-assisted, on organic light-emitting devices based on parahexaphenyl are presented in this article.
Abstract: We present femtosecond pump-probe measurements, both conventional and electric field-assisted, on organic light-emitting devices based on para-hexaphenyl. The dominant triplet exciton generation mechanism is assigned to nongeminate bimolecular recombination of photogenerated, spin-$\frac{1}{2}$ polarons. This process is active within a few hundred femtoseconds after photoexcitation and involves about 20% of the initially excited states. At higher photoexcitation densities, we observe an additional triplet generation mechanism, which occurs in the 10-ps time domain, due to fusion of singlet excitons and subsequent fission into correlated triplet pairs. The latter decay on the ${10}^{2}\ensuremath{-}\mathrm{ps}$ time scale by geminate recombination.
TL;DR: In this article, diffusivity of excess carriers in InGaN multiple quantum wells by near-field optical imaging of photoluminescence profiles created with spatially inhomogeneous photoexcitation, complemented by spatially integrated time-resolved measurements is investigated.
Abstract: We investigate diffusivity of excess carriers in InGaN multiple quantum wells by near-field optical imaging of photoluminescence profiles created with spatially inhomogeneous photoexcitation, complemented by spatially integrated time-resolved measurements. Nominally similar samples display a wide range of behavior in terms of the impact of localized states under moderate (n∼5×1017 cm−3) electron-hole (e-h) injection. By contrast, in the high density regime where present laser diodes operate (n∼1019 cm−3), radiative recombination is dominated by electronic action within the extended states.
TL;DR: In this article, the authors investigated the peculiarities of photoinduced low-spin (LS)→high-spin transition in spin-crossover complexes, such as the threshold behavior in the excitation light intensity for phase conversion and the existence of the incubation period.
Abstract: We explain theoretically the peculiarities of photoinduced low-spin (LS)→high-spin (HS) transitions in spin-crossover complexes, such as the threshold behavior in the excitation light intensity for phase conversion and the existence of the incubation period. Our investigation is based on a model where a single complex is described by the two electronic states and the breathing oscillation mode with the long-range interaction among the complexes. As the spin transition processes, we take into account the LS→HS photoexcitation process and the HS→LS nonradiative decay process. The rate for the latter process is sensitive to the LS fraction in the crystal because the potential barrier for the HS→LS decay is dependent on the LS fraction through the long-range interaction among the complexes; the lifetime of the metastable HS state becomes longer as the LS fraction decreases. Such sensitivity leads to the nonlinear temporal evolution for the LS fraction, which coincides with the experimental results.
TL;DR: In this paper, the authors used nonadiabatic quantum molecular dynamics simulations to simulate the pump-andprobe photoexcitation experiments of the ground state equilibrium solvated electron in methanol carried out by Barbara et al.
Abstract: Nonadiabatic quantum molecular dynamics simulations have been performed to simulate the pump-and-probe photoexcitation experiments of the ground state equilibrium solvated electron in methanol carried out by Barbara et al. [Chem. Phys. Lett. 232, 135 (1995)]. We have characterized both the time evolution of the quantum solute, the solvated electron, and the solvation response of the classical methanol bath. The quantum energy gap provides an excellent tool to gain insight into the underlying microscopic details of the solvation process. The solvent response is characterized for both processes by a fast Gaussian component and a biexponential decay. The present results suggest that the residence time of the solvated electron in the first excited state is substantially longer than inferred from the cited experiments. The experimentally observed fast exponential portion of the relaxation more likely corresponds to the adiabatic solvent response than to the lifetime of the excited state electron. By comparing to photoexcitation simulations in water, it is shown that the simulated excited state lifetime is about three times longer in methanol than in water, predicting a less substantial increase than a recent calculation based on nonadiabatic coupling elements alone. Hydrogen-bonding statistical analysis provides interesting additional details about the dynamics. We find that the hydrogen-bonding network is significantly different in the first solvent shell around the electron in ground and first excited states, the distribution around the latter, larger and more diffuse, ion resembling more that of the pure liquid. Transformation of the corresponding hydrogen bonding structures takes place on a 1 ps time scale.
TL;DR: In this article, the ratio of the s and d Auger-decay amplitudes and their phase difference for the resonant Auger transition 2p 3 24s! 3s213p214s 2P was determined from the measurement of the angular correlation between the resonance and the subsequent second-step Auger emission, as well as the angular distribution measurements for these two electron emissions.
Abstract: We have determined the ratio of the s and d Auger-decay amplitudes and their phase difference for the resonant Auger transition 2p 3 24s ! 3s213p214s 2P from the measurement of the angular correlation between the resonant Auger emission and the subsequent second-step Auger emission, as well as the angular distribution measurements for these two electron emissions. The analysis of the experimental data is based on the nonrelativistic LSJ coupling approximation.
TL;DR: In this article, the photoisomerization dynamics of 4-(dimethylamino)azobenzene (DMAAB) were studied using subpicosecond pump-probe spectroscopy.