title: Experimental technique using FTIR to estimate IR optical properties at variable temperatures: application to PMDA-ODA polyimide thin films from 100 to 380 degrees C.
abstract: An experimental technique is presented to measure reflectance at high sample temperature with respect to room temperature in the infrared using Fourier transform infrared fitted with a reflectometer. Sample temperature artifacts are accounted for by sequential measurements taken with the lamp source on and with the lamp source off. The sequential measurements are shown mathematically to correct for the modulation of sample and detector thermal emissions. Further, the technique is applied to a polyimide (PMDA-ODA) film on a layer of gold deposited on a thermally oxidized Si wafer. It is shown that the optical properties (index of refraction and extinction coefficient) remain relatively constant with temperature (from room temperature to 380 degrees C) in the 4000-6000 cm(-1) spectral region. The significant changes that occur with temperature are the change in thickness of the film and also the spectral properties in the 2000-4000 cm(-1) region. Also, by using a Lorentz oscillator model, it is shown that this method is able to discern that spectral features corresponding to the OH stretching bands at 3630 and 3470 cm(-1) show significant variation with increasing temperature.
authors.affiliation: Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, 1206 W. Green Street, Urbana, IL 61801, USA.
authors.forename: Ramesh
authors.initials: R
authors.lastname: Chandrasekharan
authors.forename: Richard I
authors.initials: RI
authors.lastname: Masel
authors.forename: Mark A
authors.initials: MA
authors.lastname: Shannon
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D007094:Imides / Q000737:chemistry*; D007259:Infrared Rays; D008567:Membranes, Artificial; D008956:Models, Chemical; D017550:Spectroscopy, Fourier Transform Infrared / Q000295:instrumentation / Q000379:methods*; D013696:Temperature
chemical_list: D007094:Imides; D008567:Membranes, Artificial