10min:

BRANT JONES, JINGANG ZHOU, LEI YANG, C. Y. NG, Univeristy of California, Davis One Shields Avenue Davis, CA 95616.

Single-photon Rydberg tagging time-of-flight study on oxygen atom has been firstly demonstrated. The pulsed field ionization photoion (PFI-PI) spectrum for oxygen atoms O(³P_2,1,0) resulting from the 193.3 nm photodissociation of SO₂ have been measured using tunable vacuum ultraviolet (VUV) laser radiation in the frequency range of 109 200 - 110 000 cm^-1. The PFI-PI measurement reveals over 120 Rydberg lines, which have been assigned as Rydberg states [2s²2p³ (⁴S^o_3/2) nd ³D (n = 12-62)] converging to the ground ionic state O⁺(⁴S^o_3/2) formed by the VUV excitation of O(³P_2,1,0). The identification of these Rydberg series has led to the development of the single-photon O-atom Rydberg tagging time-of-flight method. Oxygen atoms excited to high-n Rydberg levels were field ionized at the detector. As expected, the translational energy distribution obtained from oxygen atom Rydberg tagging time-of-flight measurement has a higher energy resolution than, but agrees with that derived from the velocity mapped images of the SO/O radical photofragments. Both confirm vibrational structure related to the formation of SO in the = 0,1,2 levels, with = 2 dominating the partition of available energy. This novel single-photon VUV-excited atom Rydberg tagging technique may prove to be universally applicable to other atoms, and thus become a promising avenue for future photodissociation and reaction dynamic studies.