Voigt profile characterization of copperKα

We report a characterization of the Cu K α profile and a transferable determination of the 2p satellite line using a new Voigt methodology which generates improved fits, smaller residuals and details of Compton profile features. The K α 1, 2 emission of Cu was obtained from a rotating anode through a monolithic Si channel-cut monochromator. Least-squares fitting of a minimum set of Voigt profiles reached a noise limit. Sufficient statistical information and resolution permits the determination of major and minor peak components in a fully-free least-squares analysis rather than the previous constrained single peak-by-peak method. Relative energies of the component Voigts within each profile, linewidths and K α 1 / K α 2 peak intensity ratios, are compared to the previous best empirical sum of Lorentzian-slit peaks, clearly demonstrating that a sum of Voigt profiles provides a superior fit to the observed profile. 104 profiles at accelerating voltages from 20 kV through 50 kV provided a stable unique profile across the broad range of 2.5 − 6.25 times the characteristic energy. This robustness proves the stability of Cu K α for use in high accuracy calibration, and supports the validity of the impulse approximation across this range of energy. The lineshape, contributions to noise broadening, the quantum yield and the Fano factor, relevant to spectral profiling, are discussed.