Structure and wavelength of the Cu K alpha 2 x-ray emission line.

Abstract

The Cu K\ensuremath{\alpha} emission spectrum was measured with a novel channeled monolithic double-crystal spectrometer. The wavelength of the Cu K${\ensuremath{\alpha}}_{2}$ line was determined to be \ensuremath{\lambda}(Cu K${\ensuremath{\alpha}}_{2}$)=1.544 425 6 A\r{} (1.2 ppm). A small shoulder was detected on the low-energy side of the K${\ensuremath{\alpha}}_{2}$ peak at a shift of 2.2 eV. To an accuracy lower than 1%, no other structure was detected. The width and asymmetry parameters obtained for the K${\ensuremath{\alpha}}_{2}$ peak are in good agreement with previous measurements. The K${\ensuremath{\alpha}}_{2}$ line shape is analyzed within the framework of the radiative-Auger and many-body-excitation theories of x-ray emission. A well-defined lifetime width of the K${\ensuremath{\alpha}}_{2}$ line is obtained, yielding a K-level width of 1.56\ifmmode\pm\else\textpm\fi{}0.04 eV, in excellent agreement with theoretical and semiempirical predictions. The applicability of the radiative-Auger, multivacancy, and many-body theories to the measured data is discussed.