Interactions of Blackbody Radiation with Atoms

Abstract

Blackbody radiation affects low-frequency ($h_{\nu }\ll \mathrm{kT}$) atomic transitions both by inducing transitions and producing ac frequency shifts, important effects that have previously been ignored. Here we report the calculation and experimental observation of a manifestation of the former, the threefold reduction of the Na $\mathrm{np}$ radiative lifetimes by 300-K blackbody-radiation-induced stimulated emission and absorption. Estimates of ac frequency shifts for Rydberg and ground-state atoms are given.