TY - GEN
T1 - Rotationally resolved threshold photoionization of H2S
AU - Wiedmann, Ralph T.
AU - White, Michael G.
PY - 1992
Y1 - 1992
N2 - Threshold spectroscopy based on pulsed field ionization (PFI) has been used in conjunction with a VUV laser source to obtain the rovibronic distributions of molecular cations following single photon ionization. The technique selectively detects electrons produced from field ionization of very high-n Rydberg levels (n ≥ 200) which lie within 1 - 2 cm-1 of each rovibronic threshold. Since the oscillator strength is continuous across an ionization threshold, the PFI spectrum reflects the rovibronic state population at threshold. The nascent rotational state distribution of the molecular ion reflects the exchanges of energy and angular momentum in the `scattering' of the photoexcited electron with the anisotropic molecular ion potential. Rotationally resolved studies on several molecular systems (O2, HCl, OH(OD), H2O and N2O) have shown that photoionization can lead to large changes in core rotation, e.g., ΔJ = J+ - J' ≤ 5 for O 2+, when accompanied by ejection of photoelectrons with high orbital angular momentum (l ≥ 3). For photoionization of nonlinear molecules (H2O), transitions between asymmetric top levels involving the rotational angular momentum projections, Ka,Kb,Kc, permit resolution of the photoelectron continua according to symmetry. PFI studies on the van der Waals dimer, Xe2, demonstrate the utility of this technique for investigating low frequency vibrations in molecular cations and for studying minor species (≤ 1%) in molecular beams.
AB - Threshold spectroscopy based on pulsed field ionization (PFI) has been used in conjunction with a VUV laser source to obtain the rovibronic distributions of molecular cations following single photon ionization. The technique selectively detects electrons produced from field ionization of very high-n Rydberg levels (n ≥ 200) which lie within 1 - 2 cm-1 of each rovibronic threshold. Since the oscillator strength is continuous across an ionization threshold, the PFI spectrum reflects the rovibronic state population at threshold. The nascent rotational state distribution of the molecular ion reflects the exchanges of energy and angular momentum in the `scattering' of the photoexcited electron with the anisotropic molecular ion potential. Rotationally resolved studies on several molecular systems (O2, HCl, OH(OD), H2O and N2O) have shown that photoionization can lead to large changes in core rotation, e.g., ΔJ = J+ - J' ≤ 5 for O 2+, when accompanied by ejection of photoelectrons with high orbital angular momentum (l ≥ 3). For photoionization of nonlinear molecules (H2O), transitions between asymmetric top levels involving the rotational angular momentum projections, Ka,Kb,Kc, permit resolution of the photoelectron continua according to symmetry. PFI studies on the van der Waals dimer, Xe2, demonstrate the utility of this technique for investigating low frequency vibrations in molecular cations and for studying minor species (≤ 1%) in molecular beams.
UR - https://www.scopus.com/pages/publications/0026435278
U2 - 10.1117/12.58144
DO - 10.1117/12.58144
M3 - Conference contribution
AN - SCOPUS:0026435278
SN - 0819407844
SN - 9780819407849
T3 - Proceedings of SPIE - The International Society for Optical Engineering
SP - 273
EP - 281
BT - Proceedings of SPIE - The International Society for Optical Engineering
PB - Publ by Int Soc for Optical Engineering
T2 - Optical Methods for Time- and State-Resolved Chemistry
Y2 - 23 January 1992 through 25 January 1992
ER -