Electric Field Effect on Condensed-Phase Molecular Systems. IV. Conformational Change of 1,2-Dichloroethane in a Frozen Molecular Solid

Abstract

In this work, we studied the effect of an externally applied electric field on the conformation and orientation of 1,2-dichloroethane (DCE) in a frozen molecular solid. An electric field in the order of 108 V m–1 was applied across the sample by means of interfacial charging of Cs+ ions. Reflection absorption infrared spectroscopy (RAIRS) was used to monitor the gauche/trans conversion and reorientation of the DCE molecules due to an electrostatic interaction with the field. trans-DCE molecules were converted to gauche conformers via internal C–C rotation with the conversion efficiency of 24% at the field strength of 1.5 × 108 V m–1 and temperature 75 K. gauche-DCE molecules were reoriented along the field at an average tilt angle of 36° under the same conditions. These field-induced molecular changes were prohibited at 8 K and visible above 50 K. Therefore, both electrostatic and thermal energies are required to induce molecular transformations in the metastable solid by overcoming the activation barrier...