Possible rotationally resolved detection of NO2 in the C̃ 2A2 state by optical–optical double resonance spectroscopy

Abstract

This Note describes the first rotationally resolved detection of NO2 in the C̃ 2A2 state by optical–optical double resonance (OODR) spectroscopy. The C̃ 2A2–X̃ 2A1 transition is symmetry forbidden. Direct experimental evidence of the C̃ 2A2 state had not been provided until the recent vibrationally resolved detection using photoelectron spectroscopy of NO−2 by Weaver et al. [J. Chem. Phys. 90, 2027 (1989)]. We have measured hundreds of the OODR spectra in the 500 ∼600 nm range and found that 11 rovibronic levels in the spectral region of 513.8∼516.2 nm belong to the Ka = 1 stack of a vibrational level of C̃ 2A2.