Intramolecular vibrational relaxation and forbidden transitions in the SEP spectrum of acetylene

Publisher Website
Google Scholar
Abstract
à 1Au→X̃ 1Σg+ SEP spectra of acetylene near EVIB=7000 cm−1 show that Darling–Dennison resonance between the cis‐ and trans‐bending vibrations is the first step in a series of anharmonic resonances which can transfer nearly all the vibrational energy out of the Franck–Condon bright states at higher energy. In addition to allowed ‖ΔK‖≡‖K’−l ‘‖=1 rotational transitions, nominally forbidden ‖ΔK‖=0,2,3 rotational transitions have also been observed due to axis‐switching and rotational‐l‐resonance. Although the range of detectable fluorescence dips is only about 30, the range of detectable SEP intensities in these spectra is probably about 500.