Laser Raman Study of Absorbed Medium Molecules without Interference from the Surrounding Medium

The refractive index (n_D) is approximately 1.51 for PVA and 1.33 for water. If swollen PVA contains, for example, 50% (v/v) of water, the refractive index should be about 1.42, and the critical angle for total internal reflection in transmission from PVA to water is 69°30'. Then, if the angle which the laser beam makes with the PVA surface is less than 20°30', the laser beam comes back into the bulk of PVA as in the case of optical fibers. This is an easily attainable condition for laser Raman spectroscopy.

Iwamoto R. Miya M. Mima S. , submitted for publication.