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)