Knowledge Bank

The first observation of the direct photodissociation of a van der Waals complex upon absorption of a photon is reported. Complexes of NO with He, Ne, and Ar were studied through their one photon fluorescence excitation and dispersed fluorescence spectra. The exciting light was generated by Raman shifting a Nd:YAG pumped, frequency doubled R6G laser in $H2$. Broad features peaking 250 to $350cm-1$ blue of the $A2\sum +(\nu \prime =0,1)-X2\pi 1/2(\nu \prime =0)$ transition of the uncomplexed NO have been assigned to complexes of He, Ne, or Ar. The breadth of these features is believed to be caused by excitation to the repulsive wall of the upper state potential. Fluorescence produced by excitation of these complexes has been dispersed, and the product state distribution of the fragment $NO\ast$ produced by the photodissociation was measured.