Isotope Effect in Continuous Ultraviolet Absorption Spectra: Methyl Bromide-d3 and Chloroform-d

Abstract

A comparison of the continuous ultraviolet absorption spectra of CH₃Br and CD₃Br indicated a nearly constant shift of +280±50 cm^—1 upon deuterium substitution. In the case of CHCl₃ and CDCl₃ the shift was less than the uncertainty of ±50 cm^—1. These results are interpreted in terms of the Herzberg‐Goodeve picture involving the carbon‐halogen bond rupture. The ultraviolet absorption spectra of CCl₄, CFCl₃, CH₂Cl₂, CF₂Cl₂, and CHFCl₂ are also reported.