1996 Volume 45 Issue 11 Pages 1059-1062
Photoacoustic spectrometry (PAS) was applied to the determination of thermal diffusivity of polyacrylamide gel (7.5% gel concentration), which was previously dried to film. Carbon black was placed on the polyacrylamide gel surface and then stuck onto a piece of double side adhesive tape, the other side being previously stuck to a sample holder for the photoacoustic cell.By phase variation of PAS, thermal diffusivity (α) of the gel was obtained at 2.02.4× 10-3 cm2/s. Ovalbumin electrophoresed on a slab of polyacrylamide gel was silver-stained and then the depth of silver deposition from the surface was determined by photoacoustic amplitude examination. Photoacoustic amplitude was plotted against thermal diffusion length μs, which was defined as μs=(2α/ω)1/2by varing the frequency (ω) of the laser beam. The silver stained layer was determined to be 18-20 μm to give an inflection point of the photoacoustic amplitude vs. thermal diffusion length of the gel. The value obtained by this method was smaller than the one obtained by microscopic observation.
