Quantitative photothermal radiometric and FT-IR photoacoustic measurements of specialty papers

Frequency-domain laser infrared photothermal radiometry (PTR) and photoacoustic Fourier transform spectroscopy (FT-IR/PAS) were used for the measurement of the thermophysical properties (thermal diffusivity, alpha, and conductivity, k) of specialty paper samples with various cotton contents. An improved one-dimensional photothermal model of a free-standing sheet of paper in air that includes both the transmission and backscattering mode was introduced. A high degree of accuracy and reliability was obtained when a multiparameter-fit optimization algorithm was used to examine the transmission and backscattered PTR experimental results. The ability to measure alpha and its variation, Delta alpha, as a result of the manufacturing process via the PTR technique is invaluable in terms of the quality control of paper products.