Rotational REMPI Spectroscopy; Halogen containing Compounds

Ágúst Kvaran*, Huasheng Wang and Áshildur Logadóttir
Science Institute, University of Iceland, Dunhaga 3, 107 Reykjavík, Iceland

"Resonance Enhanced MultiPhoton Ionization" (REMPI) rotational spectroscopy of halogen containing compounds will be reviewed. Only limited rotational structure studies of excited molecular states of halogen containing compounds are available by means of standard one photon excitation spectroscopy (absorption and fluorescence spectroscopy). REMPI, although fairly new technique, on the other hand, has proved to be very useful for deriving rotational spectroscopic parameters for excited state species. Furthermore, excited state interactions are easily detected via perturbation effects observed in REMPI spectra, thanks to the nature of the multiphoton excitation process. Effects of intermediate states on two photon resonance excitation processes and on the appearance of REMPI spectra will be dealt with. Emphasis will be laid on rotational analysis of (2+1) REMPI spectra for Rydberg and ion-pair states of the hydrogen halides (HX), the halogens (X₂) and the interhalogens (XY) with respect to derivation of spectroscopic parameters as well as understanding of state interactions and excitation mechanisms.