Selection rules for the photoionization of diatomic molecules
- 1 September 1990
- journal article
- Published by AIP Publishing in The Journal of Chemical Physics
- Vol. 93 (5), 3033-3038
- https://doi.org/10.1063/1.458837
Abstract
In the photoionization of the diatomic molecule AB to yield AB++e− the photoelectron may be charatcterized by a partial wave expansion in terms of its orbital angular momentum quantum number l. For a given value of l, conservation of angular momentum implies that transitions can only occur for ΔJ=l+ (3)/(2) , l+ (1)/(2) , ... ,−l− (1)/(2) , −l− (3)/(2) , where ΔJ=J+−J is the change (half‐integer) in the total angular momentum (excluding nuclear spin) of the AB+ ion rovibronic level and the AB neutral rovibronic level. Other selection rules are ΔΩ=−λ+ (3)/(2) , −λ+ (1)/(2) , ... , −λ− (3)/(2) , and ΔM=−ml+ (3)/(2) , −ml+ (1)/(2) , ... , −ml− (3)/(2) . In addition, for Hund’s case (a) and case (b) coupling, ΔS=S+−S=± (1)/(2) , ΔΣ=± (1)/(2) , and ΔΛ=−λ, −λ±1. Parity selection rules have been derived for transitions connecting levels described by one of the four coupling schemes, Hund’s case (a), case (b), case (c), and case (d). In particular, for a case (a)–case (a) transition, ΔJ−ΔS+Δp+Δs+l=odd, where the symbols have their traditional spectroscopic meanings. The parity label p=0,1 has been associated with the e, f label, from which it may be shown that (e/f )↔(e/f ) for ΔJ− (1)/(2) +l=odd and (e/f )↔( f/e) for ΔJ− (1)/(2) +l=even. It also follows that ±↔± for l odd and ±↔∓for l even. Moreover, Σ± is connected to Σ± in general, but Σ± is only connected to Σ∓ for l≥2 and λ=±1 (π wave). For homonuclear diatomics, the additional selection rules are (g/u)↔(g/u) for l=odd, (g/u)↔(u/g) for l=even, and (s/a)↔(s/a) but (s/a)↔/(a/s).Keywords
This publication has 17 references indexed in Scilit:
- Production of rotationally state selected ions by resonant enhanced multiphoton ionization of CO in a supersonic free jetChemical Physics Letters, 1989
- Rotationally state-selected HBR+: Preparation and characterizationChemical Physics Letters, 1989
- High-resolution zero-kinetic-energy photoelectron spectroscopy of nitric oxidePhysical Review A, 1987
- High resolution zero kinetic energy photoelectron spectroscopy of benzene and determination of the ionization potentialThe Journal of Chemical Physics, 1987
- Rotationally resolved laser photoelectron spectra of gas-phase NO: rotational propensity rules in photoionizationThe Journal of Physical Chemistry, 1986
- Ionic rotational selection rules for (n + 1) resonant enhanced multiphoton ionizationChemical Physics Letters, 1986
- Rotationally resolved laser photoelectron spectrum of gas-phase NoThe Journal of Physical Chemistry, 1984
- Phase Conventions for Rotating Diatomic MoleculesPhysica Scripta, 1981
- The photoelectron spectrum of H2Chemical Physics Letters, 1970
- ROTATIONAL ENERGY LEVELS OF STATES AND INTENSITIES IN TRANSITIONS: APPLICATIONS TO SOME HEAVIER HYDRIDESCanadian Journal of Physics, 1967