One-color photolysis–ionization study of HN3: The N2 fragment internal energy distribution and μ-v-J correlations

Abstract

Conformation-selective photoionization of covalently-linked diaryl compounds: Excimer-mediated one-color two-photon ionization in seeded beams of 1,3-diphenylpropane Excited stateselected transition metal cations from onecolor UV multiphoton ionization A one-color photolysis-ionization study of the photodissociation of hydrazoic acid near 283 nm has been carried out. The N2 and NH(a I~) products have both been detected in a state-specific manner by resonance-enhanced multiphoton ionization (REMPI) in a time-of-flight mass spectrometer. The N2 fragments were observed in the v = 0 vibrational mainfold and were found to be highly rotationally excited, with an average rotational excitation of 0.79 eV. The p-J correlation parameter J<fb 2 ) for N2 was determined to be positive and approximately equal to 0.5, indicating that the angular momentum vector J tends to be parallel with the transition dipole 1'. Relatively little rotational energy was found in the NH product. From the observed polarization dependence of the NH REMPI mass peak profiles, we conclude that the recoil anisotropy parameter /3 is approximately -0.5 for low-J values and becomes positive by J = 10. The observed width of these mass peaks provides information of the fragment recoil energy, and we estimate from the NH mass peaks that approximately 1.4±0.4 eV of the available energy appears as product relative translational energy. These experimental results are interpreted in terms of our understanding of the lowest excited singlet electronic state of this molecule.

UV Photodissociation Dynamics of HN3 in 190-248 nm

“…It is known that the UV photodissociation of HN 3 occurs primarily via two spin-allowed channels [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]:…”

“…The NH+N 2 channel has been extensively studied at several different wavelengths [4,[6][7][8][9][10][11]. NH is produced in the lowest singlet (a 1 ∆) instead of the X 3 Σ − ground state because of the spin symmetry rule.…”

Photodissociation Dynamics

“…Additional examples of photodissociation/REMPI experiments include a study of HN 3 photodissociation, 50 in which both the NH(a 1 ∆) and N 2 photofragments were probed by MPI, and a study of HCl elimination from vinyl chloride. 51 However, as with photodissociation/LIF measurements, much of the interest in using REMPI to probe photodissociation stems from one's ability to extract not just rotational state information, but also velocity and alignment information for individual photofragment rotational states.…”

Ab initio molecular orbital characterization of some sources for laser-assisted radical beam epitaxy of group III nitrides

“…One of these approaches is the method of photodissociation of energetic compound beams ( PDECB ), where a beam of desired neutral free radical species is efficiently produced from a molecular beam of a purified energetic compound [7] such as azides [8] by wavelength-selective photolysis using a near-ultraviolet ( UV ) continuous-wave ( CW ) laser ( Fig. 1) [3,4].…”