Hyperfine Structure Absorption in Optically Excited Mercury Vapor

The radiation 4047, 2967 and 2752, all terminating on the $2{}_{}{}^3{}_{}{}^{}P_0^{}{}_{}{}^{}$ state of mercury, was passed through optically excited mercury vapor and the absorption of each wavelength for various lengths of excited vapor and for various pressures of admixed nitrogen was measured photometrically. With low dispersion the intensity of 2752 decreased nearly exponentially with increase in length of excited vapor giving a constant linear absorption coefficient. But the lines 4047 and 2967 were found not to obey the exponential law, the fractional decrease in intensity per unit length of path decreased rapidly as the total length of the absorbing vapor increased. With high dispersion the absorption of the five components of 4047 was strong and increased with increase of admixed nitrogen. The strongest component showed the strongest absorption and the amount of absorption decreased with decrease in intensity of components. The intensity of each component decreased nearly exponentially with increase in length of excited mercury vapor. Both components of 2967 showed strong absorption. None of the components of 4358 or 5461 showed measurable absorption.