Wave packet motion in the laser dye oxazine 1 in methanol is investigated by spectrally resolved transient absorption spectroscopy. The spectral range of 600-690 nm was accessible by amplified broadband probe pulses covering the overlap region of ground-state bleach and stimulated emission signal. The influence of vibrational wave packets on the optical signal is analyzed in the frequency domain and the time domain. For the analysis in the frequency domain an algorithm is presented that accounts for interference effects of neighbored vibrational modes. By this method amplitude, phase and decay time of vibrational modes are retrieved as a function of probe wavelength and distortions due to neighbored modes are reduced. The analysis of the data in the time domain yields complementary information on the intensity, central wavelength, and spectral width of the optical bleach spectrum due to wave packet motion.
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http://dx.doi.org/10.1021/jp057543l | DOI Listing |
J Chem Phys
December 2024
State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
Rotational excitations of reactants are often considered to have little impact on chemical reactivity compared to the excitations of vibrational modes and translational motion. Here, we reveal a significant influence of the rotational excitation of HCl on its dissociation on an Ag/Au(111) alloy surface. This finding is based on six-dimensional time-dependent wave packet calculations performed on an accurately fitted machine learning potential energy surface.
View Article and Find Full Text PDFPhys Rev E
November 2024
Department of Physics, University of Oxford, Oxford OX1 3PU, United Kingdom.
We present two methods for computing the dynamic structure factor for warm dense hydrogen without invoking either the Born-Oppenheimer approximation or the Chihara decomposition, by employing a wave-packet description that resolves the electron dynamics during ion evolution. First, a semiclassical method is discussed, which is corrected based on known quantum constraints, and second, a direct computation of the density response function within the molecular dynamics. The wave-packet models are compared to PIMC and DFT-MD for the static and low-frequency behavior.
View Article and Find Full Text PDFNanophotonics
June 2024
Department of Chemistry and Cherry Emerson Center for Scientific Computation, Emory University, Atlanta, GA, USA.
Excitation energy transport can be significantly enhanced by strong light-matter interactions. In the present work, we explore intriguing features of coherent transient exciton wave packet dynamics on a lossless disordered polaritonic wire. Our main results can be understood in terms of the effective exciton group velocity, a new quantity we obtain from the polariton dispersion.
View Article and Find Full Text PDFJ Phys Chem Lett
December 2024
Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, United States.
Conical intersections are ubiquitous in the energy landscape of chemical systems, drive photochemical reactivity, and are extremely challenging to observe spectroscopically. Using two-dimensional electronic spectroscopy, we observe the nonadiabatic dynamics in Wurster's Blue after excitation to the lowest two vibronic excited states. The excited populations relax ballistically through a conical intersection in 55 fs to the electronic ground state potential energy surface as the molecule undergoes an intramolecular electron transfer.
View Article and Find Full Text PDFJ Chem Phys
December 2024
Department of Chemistry, Aarhus University, Langelandsgade 140, 8000 Aarhus C, Denmark.
Vibrational wave packets are created in the lowest triplet state 13Σu+ of K2 and Rb2 residing on the surface of helium nanodroplets, through non-resonant stimulated impulsive Raman scattering induced by a moderately intense near-infrared laser pulse. A delayed, intense 50-fs laser pulse doubly ionizes the alkali dimers via multiphoton absorption and thereby causes them to Coulomb explode into a pair of alkali ions Ak+. From the kinetic energy distribution P(Ekin) of the Ak+ fragment ions, measured at a large number of delays, we determine the time-dependent internuclear distribution P(R, t), which represents the modulus square of the wave packet within the accuracy of the experiment.
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