MM-WAVE ABSORPTION BY 2-LEVEL SYSTEMS IN MESOSCOPIC AMORPHOUS GRAINS

Temperature dependent mm-wave (0.7-3 mm) absorption in mesoscopic amor phous silicate grains synthesized by sol-gel reaction has been measure d between 1.2 and 15 K. These amorphous powders are precursors to fors terite (Mg2SiO4), enstatite (MgSiO3) and MgO . 2SiO(2). The measured b leaching of the absorption with increasing temperature characteristic of two level system behavior is observed in all cases and the results are compared with those obtained from bulk aerogel and soda-lime-silic a glass. The weighted spectral density of two level states throughout this wavelength region is shown to be larger for all the silicate part icles when compared with bulk soda-lime-silica glass.