QUANTITATIVE-DETERMINATION OF H2, HD, AND D2 INTERNAL-STATE DISTRIBUTIONS BY (2+1) RESONANCE-ENHANCED MULTIPHOTON IONIZATION

The relationship between quantum-state populations and ion signals in (2 + 1) resonance-enhanced multiphoton ionization (REMPI) detection of H-2, HD, and D2 via the E,F 1-SIGMA-g+ (upsilon'-E = 0, J' = J")-X 1-SIGMA-g+ (upsilon",J") transition is determined by calibration against a thermal effusive source. Correction factors are obtained for 102 rovibrational levels for upsilon" = 0, 1, and 2 and J" ranging from 0 to 17. Within a given upsilon", rotational correction factors are nearly unity except for the highest J" levels. The vibrational correction factors vary with upsilon"; (2 + 1) REMPI detection is 2-3 times more sensitive to upsilon" = 1 and 2 than to upsilon" = 0. Experimental correction factors are compared with those derived from a theoretical calculation of the two-photon transition moments by Huo et al. [J. Chem. Phys. 95, 205 (1991)]. In general, the agreement is excellent, which suggests that theoretical correction factors may be used when experimental ones are unavailable.