Distinguishing geometrical conformers using Coulomb Explosion Imaging

We report the results of an experimental study on distinguishing molecular conformers using coincident ion momentum imaging. This work extends our earlier study on identifying cisand trans isomers of 1,2-dibromoethene (C₂H₂Br₂) using Coulomb explosion imaging (CEI). The experiment was performed on 1,2-dibromoethane (C₂H₄Br₂) using 140 eV photons at the Advanced Light Source (ALS). Our results suggest that CEI can distinguish between anti and gauche conformal isomers, which are only distinguished by rotation around single bond. Moreover, we can observe a change in the ratio between antiandgaucheconformers as a function of temperature. The observed breakup patterns show similarities to the related cis-trans isomers but indicate a higher fraction of sequential breakup.

Supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Science, Chemical Science, Geosciences, and Bio-Science division, under Grant No. DE-FG02-86ER13491.