Vibrational energy of the ν6 vibrational mode of ZnCH3(X2A1)

Dimethyl zinc Zn(CH3)2 in He was photolyzed at 223 nm in a flow cell at 298 K, and the photoproduct ZnCH3 was detected with laser-induced fluorescence via the Ã2E−X̃2A1 transition. The excitation spectrum showed the sharp peaks of the K structure of the 610 (v′ = 0 ← v6 = 1) vibrational band in the Ã2E1/2−X̃2A1 and Ã2E3/2−X̃2A1 transitions. A spectroscopic simulation well-reproduced not only the transition energies of the K subbands but also the intensity alternation of the peaks due to the nuclear spin statistics of the three hydrogen atoms of the methyl group. The vibrational frequency of the ν6 mode of the X̃2A1 state has been determined to be 587 cm−1, which replaces the previously reported value of 315 cm−1. The transition energies of the band origins are 23 362 and 23 617 cm−1 for the 610 bands whose upper states are Ã2E1/2 and Ã2E3/2, respectively. Based on the relevant literature studies, we have shown that the 0–1 band of the degenerate vibration of a symmetric top is allowed in the transition between electronic states at least one of which is degenerate.