Broadband Dielectric Response of Dichloromethane

Johannes Hunger, Alexander Stoppa, Andreas Thoman, Markus Walther and Richard Buchner,

Chem. Phys. Lett    471  (2009) 85-91. DOI: 10.1016/j.cplett.2009.02.024


A systematic study of the dielectric response of dichloromethane over a broad frequency range (8.5 <=n/GHz <=1000; <=4.3 THz at 25 C) at temperatures from 5 C to 35 C is reported. The spectra are best described by a superposition of three contributions. The dominating loss peak at ~70 GHz, fitted by a modified Debye equation accounting for inertial rise, represents the rotational diffusion of molecular dipoles. Additionally, two libration modes contribute, which are described by damped-harmonic oscillators of resonance frequencies ~0.9 THz and ~2.1 THz. While the latter modes reflect the anisotropy of the dichloromethane molecule, the diffusive reorientation at long times appears to be rather isotropic.

(c) 2009 Berger Georg