Quantum nonadiabatic effects in the photodissociation of vibrationally excited CH3I

Hua Guo, Kai Qin Lao, George C Schatz, Audrey Dell Hammerich

Research output: Contribution to journalArticle

49 Citations (Scopus)

Abstract

Photodissociation of vibrationally excited CH3I is studied using a time-dependent quantum mechanical formalism based on the fast Fourier transform (FFT) method. The dissociation dynamics is modeled with two active degrees of freedom, i.e., the dissociation coordinate and the C-H3 umbrella coordinate. The ground state vibrational wave functions are calculated using a time-dependent relaxation method proposed by Kosloff and Tal-Ezer. Two coupled excited states are explicitly considered in this model and the potential energy functions are taken from a previous study that was able to reproduce experiments for photodissociation of the CH3I ground state. We investigate the dissociation dynamics of the system after initial vibrational excitation, with particular attention paid to nonadiabatic transitions during the dissociation process. Our calculations show that vibrational excitation can significantly change the product I*/I branching ratio. In particular, it is found that there are significant dips in the I* yield at energies associated with minima in the absorption spectrum. These dips can be attributed to differences in Franck-Condon factors associated with the two excited state potential surfaces. Other observables of the dissociation process, such as the absorption spectrum and fragment vibrational state distributions, have also been investigated.

Original languageEnglish
Pages (from-to)6562-6568
Number of pages7
JournalJournal of Chemical Physics
Volume94
Issue number10
Publication statusPublished - 1991

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Photodissociation
photodissociation
dissociation
Excited states
Ground state
excitation
Absorption spectra
Potential energy functions
absorption spectra
ground state
Degrees of freedom (mechanics)
Wave functions
vibrational states
Fast Fourier transforms
degrees of freedom
potential energy
fragments
wave functions
formalism
products

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

Cite this

Quantum nonadiabatic effects in the photodissociation of vibrationally excited CH3I. / Guo, Hua; Lao, Kai Qin; Schatz, George C; Hammerich, Audrey Dell.

In: Journal of Chemical Physics, Vol. 94, No. 10, 1991, p. 6562-6568.

Research output: Contribution to journalArticle

Guo, Hua ; Lao, Kai Qin ; Schatz, George C ; Hammerich, Audrey Dell. / Quantum nonadiabatic effects in the photodissociation of vibrationally excited CH3I. In: Journal of Chemical Physics. 1991 ; Vol. 94, No. 10. pp. 6562-6568.
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