Abstract

Aerogels are a unique class of ultra low density solid materials with interconnected pores and porosities up to 98%. Their nanometer-sized structures create remarkable optical, electrical, thermal, and structural properties. We studied the optical properties of silica aerogels with densities ranging from 8 mg/cc to 172 mg/cc. The preparation of the aerogels studied in this paper is discussed in detail in reference 1. We report on the photoluminescence and the lifetime decay of the luminescence as well as correlate the absorption and excitation spectra. The luminescence ranges from the ultraviolet to the visible and the absorption occurs well below the bandgap of amorphous silica. The results are discussed in terms of implications for the electronic structure of aerogels as well as similarities and differences with the optical and electronic properties of amorphous silica which has densities near 2200 mg/cc. Aerogels have interesting optical properties that may enable a variety of optical applications.

© 1997 Optical Society of America