Fluorescence excitation spectrum of Ni–Ar complex

A new absorption band is observed by a photolysis–supersonic jet experiment of nickelocene, Ni(C5H5)2, at wavelengths near the Ni(y 1D2–a 1D2) transition. This band appears only in the coexpansion of nickelocene with Ar or Ar in He. Taking into account dependencies of the band intensity on the photolysis laser power and nozzle pressure, this band is attributed to the transition of a Ni–Ar van der Waals complex. Since dispersed fluorescence of this band consists entirely of atomic transitions of Ni, the excited state of the Ni–Ar complex is considered to predissociate into Ni*+Ar with a very short lifetime. Analysis of the vibrational structure gives the excited-state binding energy D0′=51.7 cm−1.