Full-dimensional Franck-condon Factors In The Harmonic Normal Mode Basis For The à 1au-x̃ 1σg+ Transition Of Acetylene

Park, Barratt

Permalink

https://hdl.handle.net/2142/51029 Copy

Description

Title

Full-dimensional Franck-condon Factors In The Harmonic Normal Mode Basis For The à 1au-x̃ 1σg+ Transition Of Acetylene

Author(s)

Park, Barratt

Contributor(s)

Field, Robert W.

Issue Date

2014-06-16

Keyword(s)

Mini-symposium: Spectroscopy in Kinetics and Dynamics

Abstract

Methods developed by J. K. G. Watson for calculation of Franck-Condon Factors in systems undergoing linear $\leftrightarrow$ bent electronic transitions in the harmonic normal mode basis have been extended to the acetylene $\tilde{\mathrm{A}}$ $^1$A$_u$---$\tilde{\mathrm{X}}$ $^1\Sigma_g^+$ transition in full dimension. Because the intensity of the overlap accumulates away from linear geometry, the Hamiltonian of the linear $\tilde{\mathrm{X}}$ state may be approximately separated into 3 rotations and $3N-6$ vibrations, resulting in a one-to-one correspondence between the normal modes in the linear and bent geometries. The calculated results reproduce experimental intensities quantitatively only at low quanta of vibrational excitation due to the exclusion of anharmonic effects. However, the qualitative results explain a number of observations that were previously not understood. A change of basis to local bending modes of the $\tilde{\mathrm{X}}$ state has been performed to investigate Franck-Condon access to zero order bright states with extreme local bend excitation. These states are known to emerge above 12 quanta of bend excitation and are of interest because the local bending mode lies along the reaction coordinate in the acetylene $\rightleftharpoons$ vinylidene isomerization. The results indicate that the best strategy for reaching extreme local benders involves Stimulated Emission Pumping from $\tilde{\mathrm{A}}$-state levels with high excitation in $\nu_3'$ and $\nu_4'$, contrary to existing semi-classical arguments that $\nu_6'$ grants the best access to local bend states.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

English

Permalink

http://hdl.handle.net/2142/51029

DOI

https://doi.org/10.15278/isms.2014.MH04

Copyright and License Information

Copyright 2014 by the authors. Licensed under a Creative Commons Attribution 4.0 International License. http://creativecommons.org/licenses/by/4.0/

Owning Collections