A LASER-LIGHT SOURCE FOR CIRCULARLY-POLARIZED VUV RADIATION

A laser-based light source for circularly polarized VUV radiation gene rated by nonlinear sum-frequency mixing is described. By choosing an a ppropriate nonlinear resonant process a light flux of up to 6 x 10(10) photons s(-1) at a bandwidth smaller than 1.2 cm(-1) is achieved. The determination of the polarization state is performed by means of usin g a four-mirror analyser. A degree of circular polarization greater th an 0.99 was found for several mixing processes. These properties make this instrument an ideal source for high-resolution spectroscopic stud ies of polarization-dependent photo-ionization or photoemission at pho ton energies up to 14 eV.