X-Ray Yield and Line/Background Ratios for Electron Excitation

X-ray yield in photons/sr/electron was measured for the Kα lines of Ti, Cr, Mn, Fe, Cu, Zn, Ge, Zr, and the Lα lines of Ta and Au. Incident electron energy was varied from 11 to 38 keV, and for some elements the take-off angle for emerging x rays was varied from 6 to 45 deg. Theoretical yield values calculated after the method of Metchnik and Tomlin showed an average deviation of about 30% from the measured values, a very satisfactory agreement. Line/background ratios were also measured for the same elements and conditions. Normalization to the natural x-ray line breadths gave ratios between 100/1 and 26 000/1 depending on the element and experimental conditions. Line/background ratios are consistently larger at low take-off angles indicating that the characteristic radiation must be generated relatively closer to the surface than the continuum of the same wavelength.