Measurements of circular polarization correlations following excitation of Ar and Kr by electron impact

Abstract

Abstract. We report measurements of the circular polarization correlation parameter P3 for the excitation of the 4s'[1/2]j= I state in Ar by 40 eV electrons and for the excitation of the Kr 5 s [3/2]j = ~ state by 30 eV electrons at electron scattering angles up to 50 °. The measured Ar data are compared to predictions of a distorted wave Born approximation (DWBA). The agreement is in general not very good with theory predicting 14 values considerably larger than the measured values in the regime of small scattering angles. In Kr, where the measured data are compared to theoretical predictions from a DW-BA, a first-order many-body theory (FOMBT) and a relativistic distorted wave theory (RDW), the level of agreement between experiment and theory is somewhat better. The measured P3 parameters in conjunction with the previously measured linear coherence parameters P~ und P2 under the same scattering conditions yield the total polarization P+ which is a measure for the level of cohertot ence in the excitation process. In both cases studied here, we found values of eliminate /~+ that were consistent tot with a fully coherent excitation process.

Calibration of a vacuum ultraviolet (VUV) polarization analyser

“…The first report of the use of a reflection-type polarization analyser operating below the LiF transmission cut-off for the polarization analysis of atomic line radiation produced by electron impact was published by Williams [6]. Subsequently, McConkey and co-workers 17-91 developed a doublereflection analyser for linear and circular polarization analysis using optically flat gold-coated mirrors which is now used in several laboratories [3,IO]. This device has a broad operating range from below 50 nm to about 150 nm.…”