SINGLE-PHOTON VACUUM ULTRAVIOLET RYDBERG TAGGING TIME-OF-FLIGHT STUDY OF NASCENT O($^{3}$P$_{2,1,0}$) FORMED IN THE 193.3 NM PHOTODISSOCIATION OF SO$_{2}$

Author Institution: Univeristy of California, Davis One Shields Avenue Davis, CA 95616Single-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($^{3}$P$_{2,1,0}$) resulting from the 193.3 nm photodissociation of SO${_2}$ 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 [2s$^{2}$2p$^{3}$ ($^{4}$S$^{o}$$_{3/2}$) nd $^{3}$D (n = 12-62)] converging to the ground ionic state O$^{+}$($^{4}$S$^{o}$$_{3/2}$) formed by the VUV excitation of O($^{3}$P$_{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 $\nu$ = 0,1,2 levels, with $\nu$ = 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