Mass absorption coefficient of tungsten for 1600–2100 eV

The transmission of soft x rays with photon energies from 1606 eV to 2106 eV was measured for tungsten using thin-film samples and a synchrotron source. This region includes the MIV and MV edges. The two tungsten films had thicknesses of 107.7±10 nm and 51.5±10 nm; the intensity of the transmitted x rays was measured with a silicon photodiode. The values for the mass absorption coefficient reported here were determined from the ratios of the transmission through the two samples, i.e., through a net 56.2±14 nm of tungsten, and some additional constant factors. The MV,IV edges have widths (10%--90% after background subtraction) of 33±5 eV and 28±5 eV, respectively, compared to zero width in all x-ray tables based on atomic form factors and to 41 eV and 44 eV within a real-space multiple-scattering theory. The measurements are relevant to microspectroscopy and microtomography of integrated circuit interconnects and may be applicable to accurate measurement of the mass absorption coefficients of similar dense elements.