The infrared dielectric tensor and axial dispersion in caesium L-malate monohydrate

• Published in: Journal of physics. Condensed matter Vol. 19; no. 17; p. 176225
• Main Authors: Ribeiro, J L, Vieira, L G, Tarroso Gomes, I, Isakov, D, de Matos Gomes, E, Belsley, M
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 30.04.2007; Institute of Physics
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Infrared and raman spectra and scattering; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Organic compounds, polymers; Physics; Dielectric dispersion; Reflectivity; Polarization; THz range; Reflection spectrum; Cesium compounds; Electro-optical effects; Dielectric tensor; Phonons; Malic acid; Infrared spectra; Monoclinic lattices
• ISSN: 0953-8984; 1361-648X
• DOI: 10.1088/0953-8984/19/17/176225

Caesium hydrogen L-malate monohydrate (CsH(C(4)H(4)O(5))·H(2)O) is a novel coordination compound of L-malic acid and caesium that crystallizes into a monoclinic structure and shows promising properties for application as a piezoelectric, pyroelectric and electro-optic material. In the present work we use polarized infrared reflectivity measurements to investigate the dielectric tensor of the material in the spectral range of 40-4000 cm(-1). The use of a three-polarization technique allows us to obtain from the reflectivity data the parameters that characterize the B phonons with wavevectors varying in the plane perpendicular to the monoclinic axis. Consequently, we are able to monitor the frequency dependence of the orientation of the principal dielectric axes in this plane. Using these results we can evaluate the role of polar phonons in the low frequency dielectric response, characterize the dielectric tensor in the terahertz frequency range and describe the axial optical and dielectric dispersion over the frequency range investigated.