HIGH-PRECISION IDENTIFICATION OF MORPHOLOGY-DEPENDENT RESONANCES IN OPTICAL PROCESSES IN MICRODROPLETS

The spectroscopy of the morphology-dependent resonances of a microdrop let has been studied at high precision. The line positions are shown t o reveal optical dispersion and permit the refractive index to be dete rmined with sufficient accuracy to provide an estimate of the droplet cooling that is due to evaporation. Comparison of the remaining discre pancies in mode positions for different radial modes indicates a small temperature gradient near the surface. Both the cooling and the tempe rature gradient are compatible with thermodynamic estimates. The mode quantum numbers are identified with high confidence, and the systemati cs of the line intensities permit an estimate of the extra radiative l oss 1/Q(L) over and above that predicted by Lorenz-Mie theory for a pe rfect homogeneous microsphere, for example, that which is due to inter nal scattering, with Q(L) almost-equal-to 2 x 10(8) for first-order mo des.