INFLUENCE OF HIGH-PRESSURE ON SCATTERING OF LIGHT BY XEROGELS

Scattering of light by dry silica gels has been measured under high hy drostatic pressure. The samples of silica gel were placed in a high-pr essure optical gas chamber with argon as the working gas and illuminat ed by monochromated light of wavelength in the range 400-550 nm. The i ntensity of the scattered light was measured perpendicular to the inci dent direction. The range of applied pressure was 0.1-450 MPa. The int ensity of scattered light decreases with increasing wavelength and pre ssure. The Mie theory is employed to explain the experimental results. The estimated mean value of the radius of the scattering centers, a, increases from 37 nm to 62 nm with pressure. At the same time, the con centration of the centers, N-0, decreases from 2.6 X 10(18) m(-3) to 2 X 10(16) m(-3). The agglomeration caused by high pressure is partiall y non-reversible.