Interaction of Molecular BF+ and BFJ ions with Gold Surfaces at Low Energies: Neutralization, Dissociation, and Deposition

The surface reactions induced by BF4 and BF₂4 bombardment of gold at 10–250 eV were studied with a mass-separated low energy ion beam system. The energy distributions of dissociative ion fragments and survival molecular ions were measured by low energy ion scattering with a scattering angle of 90° and polar incident angle of 45°. The results suggest that neutralization of BF4 and BF₂+ via resonance charge transfer, Auger neutralization, and collisional charge exchange all contribute to the reduction of the parent ion intensity. In the study of dissociative scattering, the observed onset values of 35 eV for BF4 dissociation and 20 eV for BF₂4 dissociation indicate that dissociation occurs mainly via vibrational excitation at impulsive collision with the surface. In addition, secondary ion mass spectrometry, secondary neutral mass spectrometry, and x-ray photoelectron spectroscopy analyses of gold surfaces bombarded with BF f and BF₂+ show that the dissociation also leads to the accumulation of boron and boron fluorides on gold. © 1993, American Vacuum Society. All rights reserved.