Abstract-Terahertz disorder-localized rotational modes and lattice vibrational modes in the orientationally-disordered and ordered phases of camphor

Daniel V. Nickel,*^a   Michael T. Ruggiero,^b   Timothy M. Korter^b and  Daniel M. Mittleman^a  

*

Corresponding authors

^a 

Electrical and Computer Engineering Department, Rice University, 6100 Main St., Houston, USA
E-mail: dn4@rice.edu

^b 

Department of Chemistry, Syracuse University, 1-014 Center for Science and Technology, Syracuse, USA

http://pubs.rsc.org/en/content/articlelanding/2015/cp/c4cp04947k#!divAbstract

The temperature-dependent terahertz spectra of the partially-disordered and ordered phases of camphor (C₁₀H₁₆O) are measured using terahertz time-domain spectroscopy. In its partially-disordered phases, a low-intensity, extremely broad resonance is found and is characterized using both a phenomenological approach and an approach based on ab initio solid-state DFT simulations. These two descriptions are consistent and stem from the same molecular origin for the broad resonance: the disorder-localized rotational correlations of the camphor molecules. In its completely ordered phase(s), multiple lattice phonon modes are measured and are found to be consistent with those predicted using solid-state DFT simulations.