Ni–Ar complex studied by laser spectroscopy

Abstract

New absorption band systems are observed by a photolysis–supersonic jet experiment on nickelocene, Ni(C₅H₅)₂, at 300–305 nm region. They appear only in the coexpansion of nickelocene with Ar or Ar seeded in He. Taking into account dependences of the band intensities on the photolysis laser power and nozzle pressure, they are attributed to the transitions of a Ni–Ar van der Waals complex. Analysis of vibrational structures in these bands gives binding energies and potential parameters of the excited states of the complex. Since dispersed fluorescence of these bands consists of entirely atomic transitions of Ni, the excited states of the Ni–Ar complex are considered to predissociate to Ni* + Ar with very short lifetimes. Specific products, Ni(³F₃, ³F₄ and z  ¹P₁) from one band and Ni(z ¹D₂) from the other, are selectively formed and they suggest predissociation ia the crossings with specific dissociative potential curves. In one band system, relative yields of products depend on the vibrational levels of the excited state and give detailed information about the curve crossing. The atomic asymptotes for the excited states are assigned to be Ni(y ³D₁) and Ni(y ³D₂).