Two-photon spectroscopy, Rydberg∼valence interactions, and superexcited state dissociation of HCl probed by resonance enhanced multiphoton ionization

Abstract

The 'X+(0+) and 32-(0+) Rydberg states as well as the V'Z'(O+) valence state of hydrogen chloride isotopomers are studied using (2 + 1) resonance enhanced multiphoton ionization (REMPI) and time-of-flight mass spectrometry (TOFMS). Pulsed supersonic expansion provides suflicient rotational cooling to facilitate rotational analysis. Polarization selection in conjunction with fragment and isotope discrimination provide the first unambiguous identification of all vibrational bands from u' = 3 to 32 of the V 'X+ (0' ) state. REMPI excitation spectra from the U" = 0 level of the X '2+ (O+ ) state through vibrational levels of the broad Y 'X+ (O+ ) state suggest non-Franck-Condon transitions. Perturbations in intensity, line position, and rotational constants are consistent with the near-adiabatic nature of the short-range B '8' (Of) Rydberg state and long-range V'X+ (O+)state. Evidence for Rydberg -valence interaction and repulsive superexcited states is provided by the detection of strong H+ and Cl+ ion yields. The onset of a distinct Cl+ channel is detected for the first time and confirms the presence of at least two dissociation pathways at the three-photon energy and at large internuclear distance.

Two-dimensional resonance enhanced multiphoton ionization of HiCl; i = 35, 37: State interactions, photofragmentations and energetics of high energy Rydberg states

“…A number of spin-forbidden transitions are observed, indicating that spinorbit coupling is important in excited states of the molecule. 4,7,8,10,12,13,15,16,20 Pronounced ion-pair to Rydberg state mixings are both observed experimentally 3,4,8,10,13,15,16,20,21 and predicted from theory. 7,8,10,12,13,15,16,20 The perturbations appear either as line shifts 4,7,8,10,13,15,16,20 or as intensity and/or bandwidth alterations.…”

“…A large number of Rydberg states, several low-lying repulsive states as well as the V( 1 + ) ion-pair state have been identified. 7,8,10,12,13,15,16,20 The perturbations appear either as line shifts 4,7,8,10,13,15,16,20 or as intensity and/or bandwidth alterations. Perturbations due to state mixing are widely seen both in absorption [3][4][5] and REMPI spectra.…”

Two-dimensional (2+n) REMPI of HCl: Observation and characterisation of a new Rydberg state

“…Green et al reported a comprehensive (2 + 1) REMPI study of the HCl molecule [2][3][4][5]. In their papers more than 50 new states are reported and combined with previous work by others.…”

Three-dimensional velocity map imaging: Setup and resolution improvement compared to three-dimensional ion imaging

“…28 The same is true for the H + distribution of the photodissociation of HCl following the two photon excitation to the V 1 ͚ + -state, since it has been studied thoroughly by several groups. [29][30][31][32][33][34][35][36][37][38][39][40][41][42][43] Therefore, the energy distribution is quite well established. Moreover, the speed distribution is well suited to characterize the speed resolution.…”