Femtochemistry of bimolecular reactions from weakly bound complexes: computational study of the H + H'OD → H'OH + D / HOD + H' exchange reactions

A full-dimensional wavepacket propagation describing the bimolecular exchange reactions H + H'OD → H'OH + D / HOD + H' initiated by photolysis of HCl in the hydrogen-bound complex (HCl)···(HOD)...

Periodic orbit scar in wavepacket propagation

This study analyzed the scar-like localization in the time-average of a time-evolving wavepacket on a desymmetrized stadium billiard. When a wavepacket is launched along the orbits, it emerges on classical unstable periodic orbits as a scar in stationary states. This localization along the periodic orbit is clarified through the semiclassical approximation. It essentially originates from the same mechanism of a scar in stationary states: piling up of the contribution from the classical actions of multiply repeated passes on a primitive periodic orbit. To achieve this, several states are required in the energy range determined by the initial wavepacket.

High-dimensional exciton-vibrational wave-packet dynamics in the FMO complex. influence of site-specific spectral densities

The correlated exciton-vibrational dynamics of the Fenna-Matthews-Olson (FMO) complex is studied using Multi-layer Multi-configuration Time-dependent Hartree (ML-MCTDH) wavepacket propagation. Exciton populations and coherences are shown to be sensitive to the details of the spectral density.

Calculation of Guided Wave Dispersion Characteristics Using a Three-Transducer Measurement System

Guided ultrasonic waves are of significant interest in the health monitoring of thin structures, and dispersion curves are important tools in the deployment of any guided wave application. Most methods of determining dispersion curves require accurate knowledge of the material properties and thickness of the structure to be inspected, or extensive experimental tests. This paper presents an experimental technique that allows rapid generation of dispersion curves for guided wave applications when knowledge of the material properties and thickness of the structure to be inspected are unknown. The technique uses a single source and measurements at two points, making it experimentally simple. A formulation is presented that allows calculation of phase and group velocities if the wavepacket propagation time and relative phase shift can be measured. The methodology for determining the wavepacket propagation time and relative phase shift from the acquired signals is described. The technique is validated using synthesized signals, finite element model-generated signals and experimental signals from a 3 mm-thick aluminium plate. Accuracies to within 1% are achieved in the experimental measurements.

Role of ion-pair states in the predissociation dynamics of Rydberg states of molecular iodine

The predissociation dynamics of superexcited iodine is studied by femtosecond ion imaging spectroscopy, providing direct control of wavepacket propagation in ion-pair states.

Isotope effects in N₂O photolysis from first principles

For the first time, accurate first principles potential energy surfaces allow N2O cross sections and isotopic fractionation spectra to be derived that are in agreement with all available experimental data, extending our knowledge to a much broader range of conditions. Absorption spectra of rare N- and O-isotopologues (15N14N16O, 14N15N16O, 15N216O, 14N217O and 14N218O) calculated using wavepacket propagation are compared to the most abundant isotopologue (14N216O). The fractionation constants as a function of wavelength and temperature are in excellent agreement with experimental data. The study shows that excitations from the 3rd excited bending state, (0,3,0), and the first combination state, (1,1,0), are important for explaining the isotope effect at wavelengths longer than 210 nm. Only a small amount of the mass independent oxygen isotope anomaly observed in atmospheric N2O samples can be explained as arising from photolysis.

Isotope effects in N₂O photolysis from first principles

For the first time, accurate potential energy surfaces allow N2O cross sections and isotopic fractionation spectra to be derived that are in agreement with available experimental data (without ad hoc shifting), extending knowledge to a much broader range of conditions. Absorption spectra of rare N- and O-isotopologues (15N14N16O, 14N15N16O, 15N216O, 14N217O and 14N218O) calculated using wavepacket propagation are compared to the most abundant isotopologue (14N216O). The fractionation constants as a function of wavelength and temperature are in excellent agreement with experimental data. The study shows that excitations from the 3rd excited bending state, (0,3,0), and the first combination band, (1,1,0), are important for explaining the isotope effect at wavelengths longer than 210 nm. Only a small amount of the mass independent oxygen isotope anomaly observed in atmospheric N2O samples can be explained as arising from photolysis.