Ta(110) surface and subsurface core-level shifts and 4f sub 7/2 lineshapes

High resolution 4f core-level spectra of the Ta(110) surface region have been obtained at 80 and 300 K with 70 and 100 eV synchrotron radiation. The data show that the subsurface core-level binding-energy shift (compared to deeper lying atoms) for a close-packed bcc(110) surface can be substantial: 60 +- 25 meV for the first underlayer atoms of Ta(110).