Resonance enhanced multiphoton ionization photoelectron spectroscopy and pulsed field ionization via the F 1Δ2(v′=0) and f 3Δ2(v′=0) Rydberg states of HCl

Abstract

In this paper, we report the first rotationally resolved one‐ and two‐color resonance enhanced multiphoton ionization photoelectron spectroscopy (REMPI‐PES) study of the HCl molecule. The agreement between our experimental branching ratios and theoretical investigations is excellent. We also report the first zero kinetic energy pulsed field ionization (ZEKE‐PFI) experiments carried out in a ‘‘magnetic bottle’’ electron spectrometer. A direct comparison is made between ZEKE‐PFI and REMPI‐PES spectra for ionization via several rotational levels of the F ¹Δ₂(v’=0) and f ³Δ₂(v’=0) Rydberg states of HCl. Large differences in both the spin–orbit and rotational branching ratios are found between the ZEKE‐PFI and REMPI‐PES spectra. These differences can be understood qualitatively on the basis of rotational and spin–orbit autoionization mechanisms.