The effect of resonant collisions on the lifetime of the 6 ³P₁ state in mercury

The authors report an application of the pulsed magnetic field technique to the study of resonant inter-atomic collisions on the decay of alignment ( gamma ₂) of the 6³P₁ state of mercury. Resonance fluorescence scattered at right angles from atoms near the front face of a cell is observed; the depolarizing effect of multiple scattering is thereby reduced, allowing studies of same-isotope collisions to proceed to higher density. For this geometry the effect of wall collisions on gamma ₂ is not large. Magnetic scanning of the lamp is employed, firstly, to determine the isotopic abundance in the cell, and, secondly to enable study of both 'same-isotope' and 'different-isotope' collisions using the same lamp and cell. The results for different-isotope collisions confirm those obtained by others. For Hg ¹⁹⁸-Hg¹⁹⁸ collisions, the contribution to gamma ₂ is found to be (4.7+or-0.5)*10^-9 N cm ²s^-1, in satisfactory agreement with the theoretical value.