Ionization probabilities of a²∑⁺(v′=0,1,2) and B²∏(v′=0,2) states of NO

Abstract

Ionization probabilities of NO molecules electronically excited in the A 2∑+ and B 2∏ states have been determined by (1+1) resonance-enhanced, two-photon ionization. Various vibrational levels within these states have been excited prior to ionization. Measurements of the unsaturated ionization signal yields accurate values for the relative detection probabilities of NO of 1:(0.70±0.07): (0.67±0.11) for excitation via the γ(0-0), γ(1-1), and γ(2-2) bands, respectively, and (3.7±0.36)×10-7 and (5.8±0.65)×10-4 for ionization through β(0-0) and β(2-1) bands, respectively. Applying published data for the γ- and β-band transition probabilities allows the deduction of the ionization cross section of A 2∑+ and B 2∏ vibrational states. The respective ionization cross sections are (7.0±0.9)×10-19 cm2, (8.5±0.8)×10-19 cm2, (6.0±1.0)×10-19 cm2 for A 2∑+(v′=0, 1, and 2) and (5.0±0.5)×10-21 cm2 and (1.7±0.2)×10-20 cm2 for B 2∏(v′=0 and 2). These values are based on the experimentally determined cross section for A 2∑+(v′=0). Using a larger theoretical cross section for this state the other cross sections scale accordingly, within the experimental uncertainties. © 1996 American Institute of Physics.