Energy transfer between the 2S and 2D states in alkalis: experiments and theory

Collisional energy transfer (ET) between the 2S and 2D states of alkali atoms is reviewed. Recent experimental results on the ET in homonuclear collisions in Na, K, and Rb vapours upon cw (continuous wave) and pulsed laser excitation, as well as theoretical calculations of the respective cross sections are discussed. The mechanisms of these processes are considered in an attempt to clarify the role of the dipole-dipole interaction.