Zero kinetic energy-pulsed field ionization and resonance enhanced multiphoton ionization photoelectron spectroscopy: Ionization dynamics of Rydberg states in HBr

Abstract

The results of rotationally resolved resonance enhanced multiphoton ionization photoelectron spectroscopy and zero kinetic energy-pulsed field ionization studies on HBr via various rotational levels of the F 1 ⌬ 2 and f 3 ⌬ 2 Rydberg states are reported. These studies lead to an accurate determination of the lowest ionization threshold as 94 098.9Ϯ1 cm Ϫ1. Observed rotational and spin-orbit branching ratios are compared to the results of ab initio calculations. The differences between theory and experiment highlight the dominant role of rotational and spin-orbit interactions for the dynamic properties of the high-n Rydberg states involved in the pulsed field ionization process.

Dynamics of high-n Rydberg states employed in zero kinetic energy-pulsed field ionization spectroscopy via the F 1Δ2, D 1Π1, and f 3Δ2 Rydberg states of HCl

“…The main experimental apparatus has been discussed in detail before, 11 and only aspects concerning the ZEKE-PFI setup will be discussed. Briefly, in the ionization chamber of a ''magnetic bottle'' time-of-flight spectrometer two grids have been installed on the magnetic pole faces for the purpose of applying static and/or pulsed electric fields.…”

Characterization of spin–orbit autoionizing Rydberg states excited via one-photon absorption from the F 1Δ2 Rydberg state of HBr

“…The experimental setup has been described before, 8 and will only briefly be discussed here. The spin-orbit autoionization spectra of HBr were recorded in a ''magnetic bottle'' time-of-flight electron spectrometer.…”

“…Highly accurate spectroscopic constants of the X 2 ⌸ ionic state have previously been determined in a laser magnetic resonance study on the HBr ϩ ion. 15 The absolute ionization energy of the X 2 ⌸ ionic system, on the other hand, has recently been obtained by our group in a ZEKE-PFI study via the f 3 ⌬ 2 and F 1 ⌬ 2 Rydberg states, 8 as well as by others in a vuv ZEKE-PFI study from the ground state. 10 Combination of these data yields the necessary accurate values of the rotational ionic thresholds, 8 which are given in Table I.…”

“…15 The absolute ionization energy of the X 2 ⌸ ionic system, on the other hand, has recently been obtained by our group in a ZEKE-PFI study via the f 3 ⌬ 2 and F 1 ⌬ 2 Rydberg states, 8 as well as by others in a vuv ZEKE-PFI study from the ground state. 10 Combination of these data yields the necessary accurate values of the rotational ionic thresholds, 8 which are given in Table I. As a starting point quantum defects have been employed that derive either from ab initio calculations, 13 Rydberg states of HBr with excitation energies below the lowest ionization limit, 12,[18][19][20] or from analogous Rydberg states in HCl 3 and HI.…”

“…The density of autoionizing states near the 2 ⌸ 3/2 threshold is thus considerably lower than in HCl, and less crowded excitation spectra are expected. Equally important is the observation that ZEKE-PFI studies performed in our group 8 and by others 9 have provided for quite accurate absolute rotational ionic thresholds, thereby making a unique assignment of observed resonances feasible.…”