In the angle-averaged excitation and decay spectra of molecules, vibronic coupling may induce the usually weak dipole-forbidden transitions by the excitation intensity borrowing mechanism. The present complementary theoretical and experimental study of the resonant Auger decay of core-to-Rydberg excited CH_{4} and Ne demonstrates that vibronic coupling plays a decisive role in the formation of the angle-resolved spectra by additionally involving the decay rate borrowing mechanism. Thereby, we propose that the angle-resolved Auger spectroscopy can in general provide very insightful information on the strength of the vibronic coupling.
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http://dx.doi.org/10.1103/PhysRevLett.116.193002 | DOI Listing |
J Phys Chem Lett
January 2025
Departament de Farmàcia i Tecnologia Farmacèutica, i Fisicoquímica, Facultat de Farmàcia i Ciències de l'Alimentació, Universitat de Barcelona (UB), 08028 Barcelona, Spain.
Incorporation of environment and vibronic effects in simulations of optical spectra and excited state dynamics is commonly done by combining molecular dynamics with excited state calculations, which allows to estimate the spectral density describing the frequency-dependent system-bath coupling strength. The need for efficient sampling, however, usually leads to the adoption of classical force fields despite well-known inaccuracies due to the mismatch with the excited state method. Here, we present a multiscale strategy that overcomes this limitation by combining EMLE simulations based on electrostatically embedded ML potentials with the QM/MMPol polarizable embedding model to compute the excited states and spectral density of 3-methyl-indole, the chromophoric moiety of tryptophan that mediates a variety of important biological functions, in the gas phase, in water solution, and in the human serum albumin protein.
View Article and Find Full Text PDFJ Chem Phys
January 2025
Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, USA.
Electronic spectra for OThF have been recorded using fluorescence excitation and two-photon resonantly enhanced ionization techniques. Multiple vibronic bands were observed in the 340-460 nm range. Dispersed fluorescence spectra provided ground state vibrational constants and evidence of extensive vibronic state mixing at higher excitation energies.
View Article and Find Full Text PDFJ Phys Chem Lett
January 2025
Huygens-Kamerlingh Onnes Laboratory, Niels Bohrweg 2, 2333 CA Leiden, The Netherlands.
Fluorescence spectra of single terrylene molecules adsorbed on hexagonal boron nitride flakes were recorded at cryogenic temperatures. The pure electronic transitions of terrylene molecules are spread over a broad energy scale from 570 to 610 nm. Surprisingly, peaks in the vibrationally resolved fluorescence spectrum show intensity variations of ≤20-fold between molecules.
View Article and Find Full Text PDFNat Commun
January 2025
Department of Chemistry, KAIST, Daejeon, Republic of Korea.
Despite its profound significance, the molecular structural changes near the transition state, driven by the vibronic coupling, have remained largely unexplored, leaving a crucial aspect of chemical reactions shrouded in uncertainty. Herein, the dynamical behavior of the reactive flux on the verge of chemical bond breakage was revealed through the spectroscopic characterization of a large amplitude vibrational motion. Highly excited internal rotor states of S methylamine (CHND) report on the structural change as the molecule approaches the transition state, indicating that the quasi-free internal rotation is strongly coupled to the reaction coordinate as their energies near the maximum of the reaction barrier for the N-D chemical bond predissociation.
View Article and Find Full Text PDFJ Chem Theory Comput
January 2025
HUN-REN Wigner Research Centre for Physics, P.O. Box 49, H-1525 Budapest, Hungary.
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