Photoevaporation is the dispersal of a gas from the energy of XEUV radiation. (Thus it is not "evaporation" in the sense of a liquid changing to a gas.) The term photoevaporation is used for Molecular Clouds, Protoplanetary Disks, and the Atmosphere of planets. Due to this process, Extra Solar Planets close enough to stars emitting significant Ultraviolet radiation are expected to have had their atmosphere stripped away.
Protoplanetary Disk (PPD)