Spectral and temporal behavior of an alkali metal plasma extreme ultraviolet source for surface morphology applications

We have characterized the emission spectrum and temporal history of a pure potassium plasma. Strong broadband emission was observed around 40 nm due to 3s−3p, 3p−3d, and 3d−4f transitions in ions ranging from K2+ to K4+ at a time-averaged electron temperature of about 12 eV. The temporal behavior of this emission strongly follows the recombination phase in the laser-produced plasma and it was reproduced by a hydrodynamic simulation of the potassium plasma which accounted for atomic processes.