Bond cutting in Cs-doped tris(8-hydroxyquinoline) aluminium

A series of Cs 4d and Al 2p spectra associated with valence-band and cut-off spectra have been used to characterize the interaction between caesium and tris(8-hydroxyquinoline) aluminium (Alq(3)) molecules in a Cs-doped Alq(3) layer. The Cs 4d and Al 2p spectra were tuned to be very surface sensitive by selecting a photon energy of 120 eV at the National Synchrotron Radiation Research Center, Taiwan. A critical Cs concentration exists, above which a new Al 2p signal appears next to the Al 2p peak of Alq(3) in the lower binding-energy side. The Al 2p signal was analyzed and assigned as being contributed from a mixture of Alq(2), Alq and Al. Experimental data supported the observation that bond cutting of Alq(3) by the doped Cs atoms occurred at high Cs doping concentration. (C) 2008 International Union of Crystallography.