The determination of infrared optical constants of rare earth fluorides by classical Lorentz oscillator model

• Published in: Journal of physics. D, Applied physics Vol. 40; no. 11; pp. 3343 - 3347
• Main Authors: Su, Wei-tao, Li, Bin, Liu, Ding-quan, Zhang, Feng-shan
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 07.06.2007; Institute of Physics
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Infrared and raman spectra and scattering; Optical constants: refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of bulk materials and thin films; Other nonmetallic inorganics; Physics; Rare earths Fluorides; Reflection spectrum; Lorentz law; Infrared spectra; Absorption spectra; Optical constants; Extinction index
• ISSN: 0022-3727; 1361-6463
• DOI: 10.1088/0022-3727/40/11/013

Rare earth fluoride (REF3, RE = La, Ce, Pr, Sm, Er, Yb, Y) films were deposited on Ge(1 1 1) and silicon wafers in order to determine optical constants from the near infrared up to the high frequency tail of the reststrahlen band. The FT-IR transmission spectrum and the reflection spectrum were used to examine the infrared optical properties of the fluorides. The optical constants of the films in the infrared spectrum from 2 to 20 mum were calculated using the classical Lorentz oscillator model by fitting the transmission spectrum. The reflective spectrum of the fluorides on silicon was used to demonstrate the absorption difference in this region. It is found that the extinction coefficients of rare earth fluorides films with Pnma structure (REF3, RE = Y, Yb, Er) are larger than the other fluorides films with structure (REF3, RE = La, Ce, Pr, Sm) from 15 to 20 mum.