New continua for absorption spectroscopy from 40 to 2000 A.

The spectra of plasmas produced by focusing the output of a Q-switched ruby laser (output I J) on the rare-earth metals have been studied. From samarium (Z = 62) to ytterbium (Z = 70), strong quasi-uniform continua are emitted in the wavelength range 40-2000 A. Line emission from the target elements is absent over most of this wavelength region, particularly below about 600 A. The use of these continua as simple, reliable background sources for absorption spectroscopy in the vacuum-ultraviolet and soft x-ray region down to 40 A is demonstrated.