EXPERIMENTAL DETECTION AND THEORETICAL CHARACTERIZATION OF THE H$_2$-NH($X$) VAN DER WAALS COMPLEX
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Date
2005
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Publisher
Ohio State University
Abstract
The H$_2$-NH($X$) van der Waals complex has been examined using ab initio theory and detected via fluorescence excitation spectroscopy of the $A^{3}\Pi$ - $X$$^{3}\Sigma^{-}$ transition. Electronic structure calculations show that the minimum energy geometry corresponds to collinear H$_2$-NH($X$), with a well depth of D$_e$=116 cm$^{-1}$. The potential energy surface supports a secondary minimum for a T-shaped geometry, where the H atom of NH points towards the middle of the H$_2$ bond (C$_2v$ point group). For this geometry the well depth is 73 cm$^{-1}$. Laser excitation spectra for the complex show transitions to the H$_2$+NH($A$) dissociative continuum. The onset of the continuum establishes a binding energy of D$_0$=32$\pm$2\,cm$^{-1}$ for H$_2$-NH($X$). Fluorescence from bound levels of H$_2$-NH($A$) was not detected, most probably due to rapid reactive decay (H$_2$-NH($A$) $\rightarrow$ H+NH$_2$). The complex appears to be a promising candidate for studies of the photo-initiated H$_2$+NH abstraction reaction under conditions were the reactants are pre-aligned by the van der Waals forces.
Description
Author Institution: Department of Chemistry and Cherry L. Emerson Center for Scientific Computation, Emory University, Atlanta, GA 30322