Thermal scattering of light in quartz

Abstract

Using the λ 2536.5 mercury resonance radiation as exciter and the medium quartz spectrograph with a fine slit, one of us successfully recorded the doubling of the λ 2536.5 line in the spectrum of the light scattered by diamond, the latter itself being completely quenched by a mercury vapour filter. This doubling, as is well known, is of the nature of a Doppler effect arising from the selective reflexion of the monochromatic light by the approaching and receding sound waves of thermal origin assumed to be present in the crystal and travelling in all directions. The components are called Doppler-shifted or Brillouin components. We have now photographed the Brillouin components arising from the thermal scattering of light in quartz using the λ 2536.5 radiation from a water-cooled magnet-controlled quartz arc as exciter and a Hilger three-metre quartz spectrograph having a dispersion of 13.7 cm.^-1 in the λ 2536 region.