Mass Spectrometric Study of CH3D. Dissociation Probabilities of C–H and C–D Bonds by Electron Impact

Abstract

A pure sample of CH3D has been prepared and studied in the mass spectrometer. The mass spectrum of CH3D cannot be predicted from that of CH4 by assuming complete similarity between H and D (except mass). More information has been obtained on the difference in behavior of H and D on electron impact previously noticed by Delfosse and Hipple for C2H2D2. There is a difference in dissociation probability of C–H and C–D bonds which is approximately constant for several ionization processes and over a considerable range in electron energy. In addition to this there is a difference in behavior of H atoms in CH4 and H atoms in CH3D. In order to account for the mass spectrum of CH3D in terms of the mass spectrum of CH4 both these effects must be taken into consideration. Re-examination of the data of Delfosse and Hipple points not only to the difference between H and D atoms in C2H2D2, but also to a difference in behavior of H atoms in C2H4 and H atoms in C2H2D2.