David B. Mitzi
Journal of Materials Chemistry
The density of vibrational states in a fractal silica aerogel of Hausdorff dimension D≃2.4 has been determined using spin-echo neutron spectroscopy. A smooth phonon-fracton crossover is found with a fracton spectral dimension of {Mathematical expression}. This direct measurement of {Mathematical expression} near crossover agrees with a previous finding based on scaling Brillouin-spectroscopy results obtained with several samples. We also show that protons adsorbed in the gel vibrate with substantially higher amplitude than the silica matrix. © 1990 Springer-Verlag.
David B. Mitzi
Journal of Materials Chemistry
F.J. Himpsel, T.A. Jung, et al.
Surface Review and Letters
Xikun Hu, Wenlin Liu, et al.
IEEE J-STARS
K.N. Tu
Materials Science and Engineering: A