On the nature of NiAr +

Abstract

NiAr + ions generated in a supersonic expansion of Ni + with a 1% Ar/He carrier gas are injected into a tandem mass spectrometer and photodissociated with visible tunable laser radiation. A photofragmentation feature observed at 17984 cm − is believed to correspond to the dissociation threshold of NiAr + to excited state ( 2F 7 2) Ni + and ground state Ar. This assignment yields a prediction of 0.55 eV for the binding energy ( D 0 0) of NiAr +. The 58NiAr +/ 60NiAr + isotope shift of this spectral feature indicates the vibrational frequency in the ground state of NiAr + to be 235± 50 cm −. Thus NiAr + is a surprisingly “stiff” and strongly bound diatomic, discussed in light of a simple electrostatic (charge-induced-dipole) model of the internuclear forces in this class of molecules.