کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5396697 | 1505761 | 2009 | 6 صفحه PDF | دانلود رایگان |
Recently, there have been reports of the valence band photoemission of pentacene films grown on various substrates with particular emphasis on the highest occupied molecular orbital (HOMO) and its dispersion. In various works, evidence for HOMO band dispersion as high as 0.5Â eV, even for polycrystalline films, has been presented. In apparent contradiction to these results, we have previously reported a band dispersion of only 50Â meV, measured on a well characterised film with a single polymorph and single crystalline orientation, 5A(0Â 2Â 2). Here, we first present the two-dimensional momentum distribution of the HOMO of a 5A(0Â 2Â 2) film. Then the development of the valence band spectra for films grown at room temperature and low temperature are compared, and we show that morphological aspects can lead to the apparent observation of high HOMO dispersion. Finally, with the aid of the two-dimensional momentum distribution of the HOMO, we show that a reasonably large dispersion (0.25Â eV) does indeed exist in 5A(0Â 2Â 2).
Journal: Journal of Electron Spectroscopy and Related Phenomena - Volume 174, Issues 1â3, August 2009, Pages 22-27