Abstract-Terahertz Spectroscopy of 2, 4 Dinitrotoluene over a Wide Temperature Range (7-245 K)

Lucia Malebogo Lepodise , Joseph Horvat , and Roger Lewis

J. Phys. Chem. A, Just Accepted Manuscript

DOI: 10.1021/jp5052134

Publication Date (Web): December 16, 2014

Copyright © 2014 American Chemical Society

http://pubs.acs.org/doi/abs/10.1021/jp5052134

Previous THz spectroscopy of the TNT explosive precursor, 2, 4-dinitrotoluene (DNT), has been restricted to room temperature (apart from one set of data at 11 K). Here, for the first time, we investigate the spectrum as the temperature is systematically varied - from 7 K to 245 K. Many new features appear in the spectrum on cooling below room temperature. As well as the five absorption lines observed previously, we observe five additional lines. In addition, a new room-temperature line at 8.52 THz (281 cm-1) is observed. Six of the lines red-shift with temperature and four of them blue-shift. The blue shift is explained by interplay between intra-molecular and inter-molecular hydrogen bonds. The variation in line width and line intensity with temperature is not systematic, although a conspicuous decrease in line intensity with temperature is observed in all cases. Modeling with hybrid PBE0 and TPSSh functionals helps identify absorption modes.