Dispersions of image potential states on surfaces of clean graphite and lead phthalocyanine film

作者：Yamamoto Ryota; Yamada Takashi; Taguchi Masataka; Miyakubo Keisuke; Kato Hiroyuki S; Munakata Toshiaki^*

来源：Physical Chemistry Chemical Physics, 2012, 14(27): 9601-9605.

DOI：10.1039/c2cp40922d

Dispersions of image potential states on a graphite surface (denoted IPS1) and on 1 monolayer (ML) film (denoted IPS2) of lead phthalocyanine (PbPc) are investigated by the micro-spot angle-resolved two-photon photoemission (micro-AR-2PPE) spectroscopy. On the graphite surface, whole dispersions of the two members of IPS1 (n = 1 and 2) are observed. The n = 1 IPS1 peak is weakly visible at energy higher than the vacuum level. The effective mass of an electron in the n = 1 IPS1 becomes slightly light at the high momentum region, suggesting the interaction between the IPS1 and the unoccupied s-band of graphite. On the PbPc film, the IPS2 band forms a band gap and back-folds at the boundary of the Brillouin zone. A 1-dimensional Kronig-Penny model is used to reproduce the effective mass and the shift of binding energy.

• 出版日期2012