Experimental confirmation of the Jahn–Teller distortion of CH4+

Abstract
We report measured energy and angular distributions for H+ and Cn+ (n=2,3,4) fragments resulting from the collisional dissociation of 194 keV/amu Chn+ (n=0–4) in thin carbon foils. From the systematic trends of these ’’Coulomb explosion’’ spectra, one can obtain qualitative information on the structures of these species. In particular, the series displays a narrowing of the carbon angular and energy widths as protons are symmetrically added around a central carbon atom and provide a ’’focusing’’ effect. Because of the Jahn–Teller distortion, the widths measured for CH4+ are dramatically increased. (AIP)