Thomas Alex Stephenson

Learn More
The second OH overtone transition of the trans-perp conformer of peroxynitrous acid (tp-HOONO) is identified using infrared action spectroscopy. HOONO is produced by the recombination of photolytically generated OH and NO(2) radicals, and then cooled in a pulsed supersonic expansion. The second overtone transition is assigned to tp-HOONO based on its(More)
IR-UV double resonance spectroscopy has been used to characterize hindered internal rotor states (n(K) = 0(0), 1(1), and 1(0)) of the CN-Ne complex in its ground electronic state with various degrees of CN stretch (ν(CN)) excitation. Rotationally resolved infrared overtone spectra of the CN-Ne complex exhibit perturbations arising from Coriolis coupling(More)
The primary photodissociation dynamics of allyl chloride upon excitation at 193 nm is investigated in a crossed laser-molecular beam scattering apparatus. Tunable vacuum ultraviolet ͑VUV͒ photoionization of the products provides a unique ability to learn about the secondary reaction products of the nascent photoproducts formed. The data show evidence for(More)
The degree of vibrational excitation in the IBr fragment from the vibrational predissociation of NeIBr (A 311 1) has been measured using two-color pump-probe laser-induced fluorescence spectroscopy. We find that for the lowest initial vibrational states examined, av =-1 dissociation pathways dominate the dynamics, while this channel is closed for v> 17.(More)
The ion-pair states of molecular iodine provide a unique system for studying the efficiency, selectivity, and mechanisms of collision-induced non-adiabatic transitions. Non-adiabatic transitions between the first-tier ion-pair states in collisions with molecular partners and rare gases are analyzed and discussed. The qualitative features of the rate(More)
Nonadiabatic interactions in the NeICI van der Waals complex have been explored in the lowest energy triad ofICI ion-pair states (~39 000 cm-I). Dispersed fluorescence measurements reveal emission characteristic of multiple ion-pair electronic states, with the relative contributions from the E(0 +), P(1), and D I (2) states changing with the initial ICI(More)
The collision-induced electronic energy transfer that occurs when I 2 in the E(0 g ϩ) ion-pair electronic state collides with ground electronic state I 2 has been investigated. We prepare I 2 in single rotational levels in vϭ0 of the E state using two-color double resonance laser excitation. The resulting emission spectrum shows that the nearby (⌬T e ϭϪ385(More)
IR-UV double resonance spectroscopy has been used to characterize hindered internal rotor states (n K = 0 0 , 1 1 , and 1 0) of the CN-Ne complex in its ground electronic state with various degrees of CN stretch (ν CN) excitation. Rotationally resolved infrared overtone spectra of the CN-Ne complex exhibit perturbations arising from Coriolis coupling(More)
The IBr fragment rotational state distributions that result when the NeIBr van der Waals molecule undergoes vibrational predissociation have been measured in a pump-probe laser-induced fluorescence experiment. Independent of initial vibrational state and the number of quanta of vibrational energy lost from the I-Br coordinate, the rotational distributions(More)
The electronic energy transfer pathways that occur following collisions between I 2 in the E ion-pair electronic state ͑vϭ0, Jϭ55͒ and He and Ar atoms have been determined. The nearby D, DЈ, and ␤ ion-pair states are populated, but with relative branching ratios that vary with the rare gas collision partner. In He/I 2 collisions, the D state is(More)