  The evaporation coefficients of water in air and nitrogen were found as a
function of temperature, by studying the evaporation of pure water droplet. The
droplet was levitated in an electrodynamic trap placed in a climatic chamber
maintaining atmospheric pressure. Droplet radius evolution and evaporation
dynamics were studied with high precision by analyzing the angle-resolved light
scattering Mie interference patterns. A model of quasi-stationary droplet
evolution, accounting for the kinetic effects near the droplet surface was
applied. In particular, the effect of thermal effusion (a short range analogue
of thermal diffusion) was discussed and accounted for. The evaporation
coefficient \alpha in air and in nitrogen were found equal. \alpha was found to
decrease from ~ 0.18 to ~ 0.13 for the temperature range from 273.1 K to 293.1
K and follow the trend given by Arrhenius formula. The agreement with
condensation coefficient values obtained with essentially different method by
Li et al.[1] was found excellent. The comparison of experimental conditions
used in both methods revealed no dependence of evaporation/condensation
coefficient upon droplet charge nor ambient gas pressure within experimental
parameters range. The average value of thermal accommodation coefficient over
the same temperature range was found to be 1 \pm 0.05.
