Dresden 2009 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 23: Electronic and Optical Properties

CPP 23.3: Talk

Wednesday, March 25, 2009, 14:30–14:45, ZEU 114

Infrared Transition Moment Orientational Analysis (IR - TMOA) — •Periklis Papadopoulos, Wilhelm Kossack, and Friedrich Kremer — Universität Leipzig, Institut für Experimentelle Physik I, Linnéstr. 5, 04103 Leipzig

A novel method is suggested for unraveling the mean orientation and the molecular order parameter in any IR-transparent or translucent material under study. It is based on the analysis of IR transmission spectra as a function of polarization and an intentional inclination of the sample. Taking advantage of the specificity of the IR spectral range, it is based on the analysis of the absorption coefficient α∼⟨(µ^→·E^→)²⟩ , where mu is the transition dipole moment and E the electric field of the IR beam, in dependence on the polarization and the angle of inclination. Additionally, for non-scattering samples, the complex refractive index tensor can be determined by using the Fresnel equations. The spatial resolution of the technique is only limited by the wavelength.

Compared to other structural techniques, like X-ray scattering and NMR, this novel method has the advantage that it can give group-specific 3D structural information for samples under varying external conditions. The sample quantity requirements are minimal (down to µg) and time-resolved studies in combination with mechanical or electric measurements may be carried out.