Structure in the aluminum 1s soft x-ray appearance potential spectrum

The Al 1s level soft X-ray appearance potential spectrum for clean and oxidized Al has been observed. In the spectrum of the clean metal, structure related to an edge singularity and a plasmon satellite is distinguished. The plasmon coupling strength in the appearance potential spectrum is found to be almost equal to that in X-ray photoelectron spectroscopy and bremsstrahlung isochromat spectroscopy.