Electronic structure of aluminium trihydride studied using soft X-ray emission and absorption spectroscopy

Takeda, Yukiharu   ; Saito, Yuji  ; Saito, Hiroyuki; Machida, Akihiko; Aoki, Katsutoshi; Yamagami, Hiroshi; Muro, Takayuki*; Kato, Yukako*; Kinoshita, Toyohiko*

We have performed soft X-ray emission spectroscopy (SXES) and soft X-ray absorption spectroscopy (SXAS) experiments on aluminum hydride -AlH. The occupied and unoccupied electronic states of the Al 3 partial density of states are obtained experimentally. By comparing the data from Al metal and -AlH, a band gap with a few eV is found for -AlH. In addition, the occupied states of -AlH have a larger spectral intensity than that of Al metal, indicating an increase in the number of electrons with the Al 3 character through Al-H bond formations. The results of a band-structure calculation account for the formation of the energy gap and the increase of the Al 3 electrons qualitatively. This suggests that a covalent-like nature is important to the Al-H bond in -AlH.