Polarization measurements of Ne-like Mo32+ x-ray lines excited by an electron beam

Abstract

We present polarization measurements of the 1P1 → 2p6 1S0 resonance line of Ne-like Mo32+, commonly known as 3C, as well as the 3D1 → 2p6 1S0 intercombination line, commonly known as 3D, as a function of the electron impact energy ranging from near threshold to 6 times threshold (2.75–15 keV). In addition, the x-ray line polarization of the 3D2 → 2p6 1S0 electric quadrupole forbidden line was measured at 3 and 4 keV. Excitation of these lines was achieved with the LLNL EBIT-I electron beam ion trap. The degree of polarization of the emission lines was derived by comparing spectra recorded with a flat Ge (111) crystal spectrometer, which is sensitive to polarization, to the spectra recorded by an x-ray calorimeter, which is insensitive to polarization. The experimental measurements were compared to theoretical predictions produced using the Flexible Atomic Code, and good agreement was found.