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The ultrafast dynamics of electronic bubble formation upon excitation of the A(3sσ) Rydberg state of NO trapped in solid H[sub 2] and D[sub 2] has been studied by femtosecond pump–probe spectroscopy. The evolution of the spherical bubble is followed in real time by means of a probe pulse, which maps the transient configurations via transitions to higher-lying Rydberg states. It is found that bubble formation is a one-way process and no oscillations of the bubble are observed. In addition, thermalization of the system occurs on the time scale of bubble formation. In the process, there is a net energy flow away from the excited center and 0.55–0.6 eV leave the first shell around the impurity. We directly extract from the experimental data the time dependence of the bubble radius, which we represent by a rising exponential with time constants of 300±50 fs in solid H[sub 2] and 410±30 fs in solid D[sub 2] to reach a final radius of ∼5 Å. This is confirmed by simulations of the transients. The different energy dissipation mechanisms in the expansion of the bubble are discussed and we suggest that emission of a sound wave is the dominant one. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The ultrafast nonradiative relaxation processes after photon excitation at 266 nm of Hg[sub 2] trapped in a cryogenic argon matrix are studied by molecular dynamics with quantum transitions. Fourteen electronic surfaces and their corresponding couplings are included in the simulations. The couplings between electronic states are modeled using a diatomics-in-molecules treatment of the mixing of the different states of Hg[sub 2] induced by the Ar atoms. While the initially excited electronic state is the D1[sub u] state, we observe that after 10 ps of dynamics most of the electronic population (90%) is in the A0[sup ±, sub g] states. The majority of nonadiabatic jumps take place in the first 2 ps of the dynamics and at large Hg-Hg nuclear distances close to the Franck-Condon region of excitation. These results confirm predictions from previous experimental steady-state spectroscopic studies. Finally, we also demonstrate the conservation of vibrational coherence of the Hg[sub 2] stretching mode during the first few picoseconds, despite several nonadiabatic crossing events during this time. [ABSTRACT FROM AUTHOR]

The phase-separation dynamics of a ternary mixture (A, B and C) coupled with a reversible chemical reaction between the two constituents A and B is presented. It is demonstrated that the free-energy functional form of time-dependent-Ginzburg-Landau equation describing the phase-separation dynamics of the ternary mixture coupled with a reversible chemical reaction is similar to that of the mixture composed of a block copolymer and a homopolymer. Our simulation study reveals that for the case of equal forward and backward reaction rates, the lamellar thickness scales with the reaction rate constant as a single power law λ[sub L]∼Γ[sup -0.22], regardless of high or low reaction rate regimes. This study sheds insight to the unique features of the involvement of chemical reaction in the phase separation of the ternary mixture. If chemical reaction and phase separation take place simultaneously, the different pattern evolutions at high and low reaction rate constants are originated from the balance between the domain coarsening due to phase separation and the breakup of the continuous phase due to the chemical conversion. The different pattern evolution at high and low reaction rate constants when chemical reaction lags behind phase separation can be interpreted in terms of the discrepancy between the domain sizes at the time step immediately before the turning on of the chemical reaction and the inherent lamellar thickness. It is also pointed out that the crossover of the ternary mixture from one phase region to another, due to the concentration change between A and B, might generate interesting steady-state domain patterns. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The vibrational self-consistent field method is used to analyze the inhomogeneous spectral distribution of transitions caused by vacancies and thermally populated phonons, specializing to molecular iodine isolated in an Ar matrix. At experimentally relevant temperatures, for a vacancy concentration of 1.4%, both defect-induced and phonon-induced spectral shifts contribute to the spectral distribution. Both contributions scale linearly with vibrational overtone number. The predicted widths are consistent with reported resonant Raman spectra. In time-resolved coherent anti-Stokes Raman scattering (TRCARS) measurements, spectral indistinguishability implies that all members of the inhomogeneous ensemble contribute coherently to the detectable homodyne signal. The connection between spectral distribution and the observable in TRCARS is derived. The predicted polarization beats and free induction decay due to the inhomogeneous ensemble are in qualitative agreement with experiments. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The collision-induced electronic energy transfer that occurs when I[sub 2] in the E(0[sub g][sup +]) ion-pair electronic state collides with ground electronic state I[sub 2] has been investigated. We prepare I[sub 2] in single rotational levels in v=0 of the E state using two-color double resonance laser excitation. The resulting emission spectrum shows that the nearby (ΔT[sub e]=-385 cm[sup -1]) D(0[sub u][sup +]) electronic state is populated. The cross section for collision-induced E→D energy transfer is found to be 18±3 Å[sup 2]. A range of D state vibrational levels are populated, consistent with a model in which overlap between the initial and final vibrational wave functions is important, but modulated by propensities for small vibrational energy gaps and those energy gaps that are closely matched to the v=0→v=1 energy separation in the I[sub 2](X) collision partner. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Examines the rotational dynamics of two structurally similar dipolar probes in alkane-alkanol mixtures. Friction experienced by hydrogen bonding and nonhydrogen bonding; Structure formed by butanol molecules; Electrical interactions between solute and the solvent.

The spectroscopy and dissociation dynamics of I[sub 3][sup -] were investigated using fast beam photofragment translational spectroscopy. The photofragment yield of I[sub 3][sup -] from 420 to 240 nm was measured, yielding two broadbands at the same energies as in the absorption spectrum of I[sub 3][sup -] in solution. Photodissociation dynamics measurements performed with two-particle time-and-position sensitive detection revealed two product mass channels having photofragment mass ratios of 1:2 and 1:1. Both channels were seen at all photolysis wavelengths. Translational energy distributions show that the 1:2 products are from a combination of I([sup 2]P[sub 3/2])+I[sub 2][sup -] and I[sup *]([sup 2]P[sub 1/2])+I[sub 2][sup -]. The 1:1 mass channel is from symmetric three-body dissociation to I[sup -]+2I. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Studies the transient instability upon temperature quench in weakly ordered block copolymers microphases possessing a soft direction like the lamellar and hexagonal cylinder (HEX) phases. Reequilibration of the order parameter; Transient transverse broadening of the scattering peaks near the Bragg positions; Unusual ordering dynamics of the HEX phase of a diblock copolymer.

Presents molecular dynamics simulations of an idealized ultrafast pump-probe experiment designed to allow direct observation of the real-time dynamical response of an impulsively driven many-body bath. Electronic structure and potential functions; Molecular dynamics simulations; Synthesis of the pump-probe signal.

Studies the photodissociation dynamics of gas phase I[sup -][sub 3] after an excitation using femtosecond photoelectron spectroscopy. Coherent oscillations that correspond to vibrational excitation; Photoelectron spectrum induced by resonance impulsive stimulated Raman scattering.

Studies the potential energy surface for the proton transfer in 8-hydroxyimidazo[1,2-a]pyridine. Cartesian reaction surface Hamiltonian for the title reaction; Modeling of the motion of the proton in the plane of pyridine and imidazole rings; Degrees of freedom of the molecular scaffold.

Explains the theoretical framework behind fifth-order nonlinear Raman processes in molecular liquids using quasi-cw noisy light. Theoretical development of direct and sequential fifth-order analogs of coherent Raman scattering; Complete formalism; Applications made to simulated fifth-order signals from a variety of hypothetical molecular liquids.

Investigates the infrared-laser driven selective excitation of molecular vibrations of adsorbates at metal surfaces in the framework of time-dependent open-system density matrix theory. Emphasis on the inclusion of vibrational damping caused by the coupling of the adsorbate vibrations to possibly electronic substrate degrees of freedom.

Investigates the use of time-resolved transient grating techniques arising from four-wave mixing processes for the study of molecular dynamics in gas-phase systems. Theoretical treatments of time-dependent four-wave mixing signals; Off-resonant excitation; Atomic response; Rotational contribution.

Studies the thermal mobility of atomic hydrogen in solid argon and krypton matrices. Photodissociation of HBr achieved in an Ar matrix; Krypton matrix; Geminate recombination of photofragments in homogeneous conditions.

Examines the molecular time scale generalized Langevin equation theory as an approach to quantum dynamics in condensed phase systems. Derivation of polynomial maxtent imaging; Analysis of bath spectral densities; Description of linear chain model.

Investigates the temperature dependence of spectral densities and the theory of quantum activated rate. Results of three pulse photon echo experiments; Computation of classical spectral densities at two temperatures; Variations in the computed spectral densities at moderate frequency.

Examines the external field control of condensed phase reactions based on optimal control theory using a double well coupled to a bath. Creation of laser field integrating with the reaction coordinate; Details on the high and low barrier wells; Investigation of control fields and localization dynamics.

Describes the phenyl ring dynamics and deuteron spin relaxation in a highly ordered main chain/side chain liquid crystal polymer. Discussion of models used for different motional processes; Characterization of the intramolecular motion of phenyl rings; Rate constants for the passage across the potential barriers and libration within the minima.

Studies the two-pulse four-wave-mixing signals from molecular aggregates, including effects of two-exciton states, static disorder and exciton-phonon interaction represented by arbitrary spectral densities. Types of contributions to the signals; Analysis of information gained by resolving the signal field using Wigner spectrograms.

Explores the structural, dynamic and spectroscopic implications of large local configurational changes in electronically excited xenon-argon heteroclusters. Dynamics driven by the repulsive interaction between xenon Rydberg and the cluster argon atoms; Structural parameters for site-specific excitations; Configurational relaxation phenomena for xenon.

Studies the caged spin-orbit excited atom pairs in liquids and in cryogenic matrices. Fluorescence in the near infrared; Emission spectra analysis to characterize cage potentials and contact distances; Bimodal kinetics result of the emission from both geminate and nongeminate pairs.

Discusses the observability of electronic coherence in electron transfer reactions. Location of large-amplitude oscillations in the electronic occupation probabilities; Conditions under which experiments detecting electronic coherence should be feasible; Feynman-Vernon influence functional formalism.

Explores the energetic control of sequential and superexchange electron transfer (ET) mechanisms. Quantum-mechanical simulations and calculations for long-range ET in DBA systems; Separation of the donor and the acceptor by a bridge; ET dynamics in a Franck-Condon (FC) system; Multi-dimensional displaced harmonic potential surfaces; Superposition of superexchange and sequential mechanisms.

Explores the temporal vibrational coherence effects in nonadiabatic radiationless transitions between two electronic states in a large molecule or in the condensed phase. Role of the vibrational quasicontinuum of the final states; Treatment of the final evolution of the wave packet of states.

Presents theoretical computations of the rate in the gas and liquid phases of unimolecular reactions. Indications of previous theoretical and experimental investigations; Presentation of theoretical computations of the rate in the gas and liquid phases.

Discusses the effectiveness of femtosecond Fourier-tranform position-sensitive Kerr lens spectroscopy for obtaining the isotropic and anisotropic components of the low-frequency, intermolecular Raman spectra of liquids. Isotropic and anisotropic features compared for various liquid chemicals; Characterization of the intermolecular motions.

The trajectory of NO X 2ΠΩ=1/2,3/2(v=0) produced after excitation of 2-chloro-2-nitrosopropane S1 A 1A″ is studied by polarized 1+1′ resonance-enhanced multiphoton ionization with time-of-flight mass spectrometry detection. The correlations among the NO velocity v, angular momentum j, and the S1 A 1A″←S0 X 1A′ [n(N),π*(N=O)] transition dipole μ of the parent molecule are measured. The dissociation occurs by internal conversion to the ground S0 state or intersystem crossing to the T1 a 3A″ state and the observed speed distribution of the NO fragments is bimodal. There is no evidence for μ-v-j correlations for the products associated with the slow component of the speed distribution. For the higher speed component, the v-j correlation is a function of the NO rotational state, j, and is described by the bipolar moment β00(22). The average value of β00(22) is -0.17(±0.02) at j≊11.5–22.5, more than five times larger than predicted by statistical phase space theory for dissociation on the S0 X 1A′ surface, indicating a moderate preference for a perpendicular orientation of the NO rotational angular momentum and velocity vectors. The v and j vectors are nearly uncorrelated for low NO rotational states (j≤6.5). The μ-v correlation described by the β20(20) bipolar moment does not change with j and its average value is -0.04(±0.01) at j≊12.5–19.5. The average value of the β20(02) bipolar moment describing μ-j correlation is 0.04(±0.02) at j≊7.5–24.5. These results are consistent with a mechanism involving both impulsive force due to a barrier along the reaction coordinate on the T1 a 3A″ surface and forces resulting from the C–N–O bending and NO torsion about the C–N bond. © 1996 American Institute of Physics. [ABSTRACT FROM AUTHOR]

An increase of the translational temperature after photoexcitation to the electronically excited state of Ni2+ in aqueous solution is detected using a time-resolved transient lens method from the picosecond to millisecond time scale. Besides a large lens signal due to the volume expansion of water in the submicrosecond time range, two other lens signals are observed at an initial part of the signal. During the pump laser pulse, a convex lens signal is observed, which is attributed to the optical Kerr lens signal. After the pulse, a concave lens is created, which remains a nearly constant amplitude until the density lens signal appears. The signal is attributed to the temperature lens signal, which originates from the heat energy by the nonradiative transition of the excited state. It is found that the signal rises within 3 ps after the photoexcitation, which indicates that the temperature rise is very fast. After the fast rise, another slower dynamics (500 ps) is observed and the deactivation processes of Ni2+ in aqueous solution are discussed based on these results. © 1996 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We present a series of molecular dynamics experiments for the nucleophilic substitution reaction Cl-+CH3Cl→ClCH3+Cl- taking place in liquid simple point charge water nanoclusters containing 6, 16, and 32 solvent molecules at temperatures close to 200 K. A three-dimensional potential energy for the reagent interatomic interactions is employed. Equilibrium and dynamical aspects of the reactive process are investigated. Solvation effects lead to significant enhancements of the computed free energy barriers even in aggregates containing only six water molecules. The equilibrium spatial and orientational correlations describing the changes in the solvation structure along the reaction path are also presented. The reactive/product states are characterized by a fully solvated Cl- ion embedded within the cluster while the CH3Cl remains on the surface; at the transition state, the complex lies at the cluster surface adopting a linear geometry tangential to the cluster boundary. We have also monitored the time relaxation of the solvation structures as the system evolves from the transition to the stable product states. Our results show the reaction proceeds by a series of highly coordinated motions involving the different components of the reagent. Estimates for the rate constants in clusters of different sizes are also computed using the reactive flux correlation function formalism. © 1996 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The solvent-induced electronic predissociation [B→a1g(3Π)] following an ultrafast X→B transition in molecular iodine is studied using a classical ensemble representation of Heisenberg’s equations of motion. An N electronic state quantum mechanical Hamiltonian is used to derive (coupled) equations of motion for the population (and the coherence) of the different electronic states as well as classicallike coupled equations for the nuclear dynamics (of both the molecule and the solvent) on each electronic state. The ultrafast excitation of the intermediate B state creates a coherent vibrational motion in this bound state. The localized nature of the solvent-induced B–a1g(3Π) coupling results in a steplike depletion of the excited B state population and hence in a bulletlike appearance of population on the dissociative a1g(3Π) state twice per vibrational period. The depletion of the B state population and the appearance of products on the a1g(3Π) state are discussed as a function of solvent density and polarizability. The magnitude of the nonadiabatic B–a1g(3Π) coupling depends both on the molecule–quencher separation and on the quencher’s polarizability. It is found that at all reduced densities the small Ar atom is the most effective quencher (when compared to either Kr and/or Xe). We attribute this unexpected trend to the local density of atoms around the solute molecule. For all the rare gas solvents the local density around the iodine molecule does not quite scale with the global one and there is an observed tendency for the solvent to cluster around the solute in a T-shaped configuration. It is this close-packed configuration that compensates for the smaller polarizability of the Ar atom and hence provides for a more effective quenching. These arguments are used to explain the experimental results which demonstrate that for a series of homologous alkanes the extent of predissociation... [ABSTRACT FROM AUTHOR]

We present a theory of the statically broadened vibrational line shape of a molecule in liquid solution. In this limit of static broadening, the molecule vibrates in a static potential posed by fixed solvent molecules in a configuration chosen from the equilibrium distribution of fluid configurations. The line shape is calculated within the instantaneous normal mode approximation, in which the solute’s potential is approximated by a harmonic surface whose curvature agrees with that of the exact potential at the solute’s initial configuration. Within this approximation, the line shape is related to a configuration-averaged phonon Green’s function, which is calculated approximately with an analytical procedure. This theory represents a modification of our previous treatment of vibrational line shapes [J. Chem. Phys. 102, 2326 (1995)], in which the solvent dynamics were included. Comparison of the line shapes for static and dynamic solvents permits determination of the relative importance of static (inhomogeneous) and dynamic (homogeneous) contributions to line broadening. We carry out such comparisons for a harmonic diatomic in a Lennard-Jones solvent over a wide range of temperature and density. © 1996 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Applying the two-photon laser-induced fluorescence technique for nascent state resolved ClO(X 2ΠΩ,v,J) detection, the photofragmentation dynamics of OClO in the (A 2A211,0,0) and the (A 2A218,0,0) state is investigated at fixed photolysis wavelengths of 351 nm and 308 nm. In both experiments the product fragments are formed in their electronic ground states, namely ClO(2ΠΩ) and O(3P). A complete product state analysis proves the ClO radicals originating from the OClO(A 2A211,0,0) dissociation at 351 nm to be formed in v=0–4 vibrational states with a spin–orbit ratio of P(2Π3/2):P(2Π1/2)=3.8±0.5. The ClO fragment shows moderate rotational excitation. The obtained ClO product state distributions and the relatively high translational energy of the fragments can be explained by predissociation of the (A 2A2ν1,0,0)-excited parent molecule in the course of which the initial symmetric stretch motion (ν1) of OClO is transferred into the dissociative asymmetric stretching mode (ν3). ClO line profile measurements indicate a dissociation time of less than 0.5 ps. Resulting from the OClO(A 2A218,0,0) dissociation at 308 nm ClO is generated in very high vibrational states. The rotational excitation is comparable to that of the 351 nm photolysis study. © 1996 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The properties of the coupling between chemical oscillators were studied in the discrete chemical oscillation system which was realized by immersing cation exchange beads loaded with ferroin in the Belousov–Zabotinskii reaction solution. A phase diagram of coupling states was obtained as a function of natural frequencies of oscillators and the distance d between oscillators. The synchronization was found not to be attributed to a simple entrainment of the slower oscillator by the faster one. Various entrainments between oscillators occurred depending on ratios of natural frequencies in the uncoupled state. A chaotic behavior was found at the boundary between stably coupled regions with frequency ratios of n/1 where n is an integer. Furthermore, effects of external perturbation on the coupling were investigated. Irregular oscillations were induced by illumination with a He–Ne laser light, which strongly depended on the phase of oscillator at the beginning of illumination. Such irregular behaviors were localized within the illuminated bead. This indicates that two oscillators are decoupled by illumination. © 1995 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We report a quantum scattering calculation of energy transfer and collision-induced dissociation of HCO in collisions with Ar. The HCO rotation is treated in the infinite order sudden approximation, and the HCO vibrations are treated by the coupled-channel method. Sixty L2 HCO vibrational wave functions are included in the coupled-channel basis, of which 15 correspond to bound HCO states for zero HCO angular momentum, and the remainder represent a discretized continuum, which includes ten resonances. A simple ‘‘sum-of-pairs’’ potential is used to describe the Ar–HCO interaction, and the HCO intramolecular potential is the previous Legendre polynomial fit to ab initio calculations. Vibrational state-specific and state-to-state cross sections, averaged over the orientation of Ar relative to the CO-bond axis, are calculated over a range of translational energies. Collision-induced dissociation cross sections to form H+CO from all HCO bound states are presented, and decomposed into components corresponding to dissociation via HCO resonances and dissociation via nonresonance states. The energy transfer from selected initial states is also calculated as a function of initial relative translational energy. © 1995 American Institute of Physics. [ABSTRACT FROM AUTHOR]

A two-dimensional, two-state model is used to model the UV-laser-induced photodesorption dynamics of NH3 and ND3 from Cu(111) by solving the nuclear time-dependent Schrödinger equation. By projecting the asymptotic wave functions on the asymptotic (‘‘umbrella’’) eigenstates of NH3/ND3, we find that the molecules leave the surface vibrationally hot, in agreement with experimental data. Within individual asymptotic tunneling doublets, however, the desorbates are clearly non-Boltzmann with molecules of ‘‘gerade’’ symmetry desorbing with increased probability. Our study correlates this parity selection with details of the electronic ground state potential energy surface. An experimentally observed strong isotope effect in the desorption yields for the different isotopomers is traced back mainly to differences between the vibrational frequencies of the ‘‘umbrella’’ mode, in accord with earlier, classical models. Additionally, small tunneling and moderate zero-point contributions are observed. Finally, the possibility of bond and isotope selective photochemistry at surfaces, based on a two-photon IR+UV strategy is demonstrated. © 1995 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The velocity and angular distributions of CO2 produced by CO oxidation on Rh(111) have been measured as a function of surface temperature and oxygen coverage. Both the velocity and angular distributions are bimodal. The velocities of one component are well fit by a Maxwell–Boltzmann distribution at the surface temperature, and the angular distribution of its intensity is cosine. The second component is non-Boltzmann, and the angular distribution is sharply peaked toward normal. The average energy of this feature is a very strong function of the surface temperature, increasing with a slope of 8.7kb, where kb is the Boltzmann constant, between 475 K and 700 K. Surprisal analysis proves useful in condensing and interpreting these data. © 1995 American Institute of Physics. [ABSTRACT FROM AUTHOR]

A semiclassical time-dependent self-consistent-field approach for the description of dissipative quantum phenomena is proposed. The total density operator is approximated by a semiclassical ansatz, which couples the system degrees of freedom to the bath degrees of freedom in a self-consistent manner, and is thus in the spirit of a classical-path description. The capability of the approach is demonstrated by comparing semiclassical calculations for a spin–boson model with an Ohmic bath to exact path-integral calculations. It is shown that the semiclassical model nicely reproduces the complex dissipative behavior of the spin–boson model for a large range of model parameters. The validity and accuracy of the semiclassical approach is discussed in some detail. It is shown that the method is essentially based on the assumption of complete randomization of nuclear phases. In particular, the assumption of phase randomization allows one to perform the trace over the bath variables through quasiclassical sampling of the nuclear initial conditions without invoking any further approximation. © 1995 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Correlated rotational and translational product state distributions of the NO X 2Π1/2,3/2 (v=0) product of the dissociation of 2-chloro-2-nitrosopropane in a molecular beam following A 1A‘←X 1A’[n(N),π*(N=0)] excitation at 600 and 650 nm are measured by resonance-enhanced multiphoton ionization/time-of-flight mass spectrometry in a molecular beam. The NO speed distribution appears bimodal and the average speed increases with NO rotational quantum number. The slow component of the NO velocity distribution is attributed to dissociation on the S0 surface and the fast component to dissociation across a barrier along the reaction coordinate on the T1 surface. A two-channel dynamical model based on statistical phase space theory is used to model the correlated NO rotational and translational distributions. The experimental data are consistent with a C–N bond energy of 12 900±200 cm-1 on the S0 surface and a barrier height of 1500±200 cm-1 on the T1 surface. The high rotational excitation of NO products originating on the T1 surface can be attributed to impulsive recoil of NO from a bent C–N–O geometry atop the T1 barrier. © 1995 American Institute of Physics. [ABSTRACT FROM AUTHOR]

In a recent Letter [Chem. Phys. Lett. 221, 482 (1994)], we demonstrated that the dynamics of reduced density matrices for systems in contact with dissipative harmonic environments can be obtained in an iterative fashion by multiplication of a propagator tensor. The feasibility of iterative procedures in reduced dimension spaces arises from intrinsic features of the dissipative influence functional in Feynman’s path integral formulation of quantum dynamics. Specifically, the continuum of frequencies characteristic of broad condensed phase spectra disrupts phase coherence to a large extent, such that the dynamics of an augmented reduced density tensor becomes Markovian. In a preceding article [J. Chem. Phys. 102, 4600 (1995)] we examined in detail the formal properties of the tensor propagator. In the present paper we show that the tensor propagator can be further decomposed into a product of small rank tensors, resulting in an extremely simple and efficient numerical scheme that scales almost linearly with the dimension of the augmented reduced density tensor. Numerical application to a model electron transfer reaction is presented. © 1995 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We report a new spectroscopic measurement based on fifth order nonlinear response from a molecule in a room temperature liquid. In conjunction with conventional three pulse stimulated photon echo, detailed information on solvent–solute dynamics for a wide range of time scales has been obtained. Both the ultrafast inertial components and much slower dynamics of the solvent are found to make important contributions to the solvent relaxation. The potential of the fifth order measurements is discussed via numerical calculations using model solvent spectral densities. © 1995 American Institute of Physics. [ABSTRACT FROM AUTHOR]