High-resolution ion translational energy spectrometry of C₆₀. Excitation of singlet and triplet states in collisions with H⁺ and H₂⁺

Abstract

A new ion translational energy spectrometer has been utilised to carry out energy-loss experiments with H⁺ and H₂⁺ protectiles colliding with C₆₀ vapour at impact energies of 2-4 keV, and an energy resolution of 14-20 meV FWHM. H⁺-C₆₀ collisions allow access to the singlet manifold of electronically excited states of buckminsterfullerene which lie in the spectral region from the infrared to the vacuum ultraviolet. Corresponding experiments with H₂⁺ projectiles access both the singlet and the triplet states. Agreement was found between present measurements, theoretical predictions and electron energy loss data for H⁺-C₆₀ collisions, where only excitation to singlets is involved. However, for H₂⁺-C₆₀ the satisfactory interpretation of the spectrum will require further triplet state calculations to higher excitation enegries.