Details

Autor(en) / Beteiligte

• Virgo, Wilton L
• Bittinger, Kyle L
• Steeves, Adam H
• Field, Robert W

Titel

Contrasting Singlet−Triplet Dynamical Behavior of Two Vibrational Levels of the Acetylene S1 231B Polyad

Ist Teil von

• The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory, 2007-12, Vol.111 (49), p.12534-12537

Ort / Verlag

American Chemical Society

Erscheinungsjahr

2007

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Surface electron ejection by laser-excited metastables (SEELEM) and LIF spectra of acetylene were simultaneously recorded in the regions of the Ã1Au−X̃1Σg + nominal 213142 K a = 1 ← 00 and 213162 K a = 1 ← 00 bands near 46 140 cm-1. The upper states of these two bands are separated by only ∼100 cm-1, and the two S1 vibrational levels are known to be strongly mixed by anharmonic and Coriolis interactions. Strikingly different patterns were observed in the SEELEM spectra in the regions of the 213142 and 213162 vibrational levels. Because the equilibrium structure of the T3 electronic state is known to be nonplanar, excitation of ν4 (torsion) and ν6 (antisymmetric in-plane bend) are expected respectively to promote and suppress vibrational overlap between low-lying S1 and T3 vibrational levels. The nearly 50:50 mixed 213142−213162 character of the S1 vibrational levels rules out this simple Franck−Condon explanation for the different appearance of the SEELEM spectra. A simple model is applied to the SEELEM/LIF spectra to explain the differences between spectral patterns in terms of a T3 doorway-mediated singlet−triplet coupling model.