Characterization of Dynamical Produce-State Distributions by Spectral Extended Cross-Correlation: Vibrational Dynamics in the Photofragmentation of NH2D and ND2H

Published

February 1, 2000

Author(s)

J P. Reid, R A. Loomis, S R. Leone

Abstract

The spectral cross-corrrelation method [Jacobson et al., J Chem. Phys. 107, 8349 (1997)], developed for the identification and extraction of spectroscopic patterns, is extended to the analysis of product-state dynamical data from photofragmentation. Fragment product state vibrational distributions for the photodissociation fo ammonia and deuterated ammonia species are extracted. Since chemical isolation of the mixed isotopic parent molecules is prohibited, the photodissociation dynamics of all four parent species (NH₃, NH₂D, ND₂H and ND₃) are studied simultaneously at 13.3 nm. The electronic emission spectra from the NH₂( ²A₁), ND₂( ²A₁), and NHD( ²A₁) fragments are recorded by time-resolved Fourier transform infrared spectroscopy. Spectral signatures for the photodissociation products from each parent species are extracted by the cross-correlation method. The formalism is derived to extend the spectral cross-correlation method to dynamical reactive product state incormation. The application of the cross-correlation method to such a system, in which there is significant overlap of the quantum states of the product species from different parent molecules, represents a powerful new tool to extract the dynamical information of reactive chemical processes from a series of complex spectra. As an example, the relative quantum yields for breaking the N-H or N-D bonds of the parent molecules to form the electronically yields for breaking the N-H or N-D bonds of the parent molecules to form the electronically excited state products, as a function of NH₂, ND₂, and NHD bending vibrational state, are determined with only limited knowledge of the spectroscopic asignments. The application of the spectral cross-correlation method to probe dynamical chemical processes in other types of reactive systems is discussed.

Citation

Journal of Chemical Physics

Volume

112

Issue

No. 7

Pub Type

Journals

Keywords

ammonia, photodissociation, reaction dynamics, spectral pattern recognition

Citation

Reid, J. , Loomis, R. and Leone, S. (2000), Characterization of Dynamical Produce-State Distributions by Spectral Extended Cross-Correlation: Vibrational Dynamics in the Photofragmentation of NH₂D and ND₂H, Journal of Chemical Physics (Accessed October 7, 2024)