Jones- Note that quartz crystals shattered when the laser built up the acoustic energy. What pressures in a liquid? > > Fred - interesting observation - even without a plasma... > > (and even for those like myself who are on a brain transplant > waiting list ;-) > Don't accept one that comes from the Lone Star State,unless you want to be President. :-) > > Stimulated Brillouin Scattering is possibly active in the context > of the Letts/Cravens and other experiments recently mentioned > where lasers are used. However, one suspects that the effect would > have been much greater had terahertz lasers been available to them > and at signigicantly higher power. > A few watts of UV in a few cubic centimeter fluorescent bulb in a reflective cavity might do. If the CF gammas (> 10^20 Hz) set up phonon vibrations as suspected, high power pumping may not be required. > > Stimulated Brillouin scattering (SBS) in a plasma is said to be > due to the interaction of an electromagnetic wave and an ion > acoustic wave (Alfren wave). And one must suspect the same thing > is going-on in condensed matter to the degree that the laser light > can penetrate the material (a few microns). Ther penetration depth > for terahertz, for comparison purposes, is many cm and it can be > identical in lamda to the phonon frequency. > Water works very well as "condensed matter"as evidenced by the thesis' claim for 3rd harmonic uv. Evidently penetration depth isn't a problem.. > > A loaded D-matrix is comparable to a large number of subnanometer > "chambers" and laser light will certainly penetrate the surface - > which is hte active area anyway, but a terahertz coherent light > source (can be a diode and not a laser) would seem to be ideal. > Too bad they are not commonly available. > > SBS is identified by a characteristic "frequency shift" according > to the literature. > http://tempest.das.ucdavis.edu/mpi/SBS/SBS.html
The thesis http://www.nat.vu.nl/atom/thesis-iavor.pdf covers the mechanism very well. Fred
