Experimental detection and theoretical characterization of the H2-NH(X) van der Waals complex -: art. no. 144318

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). The 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 +/- 2 cm(-1) for H-2-NH(X). The fluorescence from bound levels of H-2-NH(A) was not detected, most probably due to the rapid reactive decay [H-2-NH(A)-> H+NH2]. The complex appears to be a promising candidate for studies of the photoinitiated H-2+NH abstraction reaction under conditions were the reactants are prealigned by the van der Waals forces. (C) 2005 American Institute of Physics.