Energy transfer in monochromatically excited nitric oxide: A2Σ+ and B2Π

Abstract

Excitation of NO molecules into specific vibration-rotation levels of the A2Σ+ and B2Π electronic states by absorption of atomic lines has been studied under various experimental conditions by observing the steady-state fluorescence spectra of the (A 2Σ+−X 2Π) and (B 2Π−X 2Π) bands. Excitation of the A 2Σ+, v′=0–3 and B 2Π, v′=3, 4 levels was achieved. The fluorescence from NO A 2Σ+, v′=0–3 was found to be quenched by NO X2Π with an effective cross section of 25 Å2. The fluorescence from NO B 2Π, v′=0, 3, 4 was found to be quenched by NO X2Π with effective cross sections of 16, 21, and 20 Å2, respectively. The anomalously efficient vibrational relaxation of NO A 2Σ+, v′=1 by NO X2Π was found to be one aspect of an efficient electronic energy exchange process. The cross sections for exchange of electronic energy between N14O16 A Σ+2, v′=0 and 1 and N1615 OX 2Π, v″=0 were found to be 12 ± 3, 7 ± 4, and 1.7 ± 0.3 Å2 for the N14O16 A, v′=1→N15O16, A, v′=1,N14O16 A, v′=0→N15O16 A, v′=0, and N14O16 A, v′=1→N15O16 A, v′=0 processes, respectively. A transition dipole-transition dipole interaction is proposed for this transfer process. Rates of electronic energy transfer from NO A2Σ+ to NO B2Π, and vice versa, in collision with NO X2Π, were also measured.