Photoionization of He and N2 by uv radiation from a copper plasma produced by a CO2 laser

Measurements of the attenuation in a background gas, He or N2, of the uv radiation produced by a 1.7-ns 4-J CO2 laser irradiation of a copper target are reported. Photoionization cross sections of 0.4 Mb in He and 0.9 Mb in N2 are obtained. The photoionizing radiation is attributed to the 110.6-Å M1 transition in copper.