Time-Resolved Photoelectron Spectroscopy of Dissociating 1,2-Butadiene Molecules by High Harmonic Pulses

Abstract

Using 42 nm high harmonic pulses, the dissociation dynamics of 1,2-butadiene was investigated by time-resolved photoelectron spectroscopy (TRPES), enabling us to observe dynamical changes of multiple molecular orbitals (MOs) with higher temporal resolution than conventional light sources. Because each lower-lying occupied MO has particular spatial electron distribution, the structural dynamics of photochemical reaction can be revealed. On the femtosecond time scale, a short-lived excited state with a lifetime of 37 ± 15 fs and the coherent oscillation of the photoelectron yield stimulated by Hertzberg-Teller coupling were observed. Ab initio molecular dynamics simulations in the electronically excited state find three relaxation pathways from the vertically excited structure in S1 to the ground state, and one of them is the dominant relaxation pathway, observed as the short-lived excited state. On the picosecond time scale, the photoelectron yields related to the C-C bond decreased upon photoexcitation, indicating C-C bond cleavage.

Time-resolved high-harmonic spectroscopy of ultrafast photoisomerization dynamics

“…On the other hand, in the present case, the molecules were excited to a real state. Hence, the observed modulations should be attributable to the vibrational modes stimulated by the ultrafast internal conversion from the excited state whose equilibrium geometry is different from that of the ground state [51,52]. In the previous TR-PES measurement, the relaxation time of the 3p x -Rydberg state of CHD was 37 ± 13 fs upon 2PA [28].…”

Time-resolved electron spectroscopy for chemical analysis of photodissociation: Photoelectron spectra of Fe(CO)5, Fe(CO)4, and Fe(CO)3

“…The Fe(CO) 4 and Fe(CO) 3 photoelectron spectra are compared here to the Fe(CO) 5 spectra, and the observed chemical shifts are explained with calculated spectra and core-hole induced changes in molecular-orbital interactions, orbital populations, and electron densities. We demonstrate how time-resolved valence and core-level photoelectron spectroscopy [17][18][19][20][21][22][23][24] thereby enable to test fundamental concepts for frontier-orbital interactions and charge-density changes in the dissociation of Fe-CO bonds. 25,26 CO to Fe σ donation and Fe to CO π back donation are reduced upon dissociation, and charge can be thought of as to flow back to the isolated constituents upon deligation, as schematically shown for two of the occupied molecular orbitals in Fig.…”

Real-Time Probing of an Atmospheric Photochemical Reaction by Ultrashort Extreme Ultraviolet Pulses: Nitrous Acid Release from o-Nitrophenol

“…19 However, the experimental verification has not been demonstrated so far. In this paper, we investigate the relaxation and dissociation dynamics of o-NP using extreme ultraviolet (EUV) light at 29.5 eV [20][21][22][23][24] as a probe to reveal the complete photochemical dissociation pathway : 1) We were able to follow the dynamics from the Franck-Condon region to product formation by TRPES upon excitation at 400 nm (3.1 eV). 2) We used multireference perturbation theory, including both non-dynamical and dynamical electron correlation, to follow the reaction processes on the excited-state potential energy surfaces and to support experimental findings.…”