SELECTIVE REFLECTION FROM MERCURY VAPOR AT HIGH PRESSURES

Selective reflection from mercury vapor in the region of the 2537 Å resonance line was investigated at pressures up to 340 atm. using reflection cells of special design. The results were interpreted on the basis of the classical theory of reflection from an absorbing medium. By fitting calculated curves to the experimental reflection contours, values of the oscillator strength, f, and the damping constant, γ, were determined. The f values so obtained are density-dependent and at high pressures are approximately equal to one half the value for the free atom. As predicted by theory, the damping constant varies directly as the density of the atoms in the vapor. This result contradicts the earlier work of Welsh, Kastner, and Lauriston (1950) in which it was concluded that γ varies as the square root of the density. A subsidiary reflection maximum was observed at 2540 Å; it is attributed to Hg2 molecules which occur in relatively large concentrations at high densities. Some preliminary observations on the selective reflection at the 1850 Å resonance line were made up to 4.4 atm.