MISC

2007年11月

Atmospheric effect of air, N(2), O(2), and water vapor on the ionization energy of titanyl phthalocyanine thin film studied by photoemission yield spectroscopy

JOURNAL OF APPLIED PHYSICS
  • Masato Honda
  • ,
  • Kaname Kanai
  • ,
  • Kenichi Komatsu
  • ,
  • Yukio Ouchi
  • ,
  • Hisao Ishii
  • ,
  • Kazuhiko Seki

102
10
開始ページ
103704
終了ページ
記述言語
英語
掲載種別
DOI
10.1063/1.2809360
出版者・発行元
AMER INST PHYSICS

The effect of atmospheric gases on the ionization energy (I) of titanyl phthalocyanine thin film was investigated by an apparatus of photoemission yield spectroscopy developed for the measurements of I for the same specimen both in vacuum and under gaseous atmosphere. It was found that the value of I is affected by the exposure to various ambient gases (i.e., air, nitrogen, and oxygen of 1 atm, and water vapor corresponding to 27% relative humidity at 300 K), and that the effect strongly depends on the gas. The ionization energies in vacuum could be determined as the onset I(0) of the cube-root plot of the photoemission yield as a function of photon energy. When the sample was exposed to gases, the cube-root plot still gives an onset, but often a long tail at the low-energy side with another onset I(t) was also observed. The first exposure to air did not affect both I(0) and I(t) much, while the following evacuation-exposure cycles caused mostly reversible decrease and increase of I(0) and I(t) by about 0.2 and 0.4 eV, respectively. Among the examined constituent gases of air, nitrogen was found to hardly affect both I(0) and I(t) except for the small temporal decrease by 0.06 eV at the first exposure. Similar trends of the change of I(0) and I(t) with those for air were found for oxygen, with the amplitudes of mostly reversible change being 0.1 eV for I(0) and 0.2 eV for I(t). Overlapped with these changes, a slow decrease of both I(0) and I(t), was also observed with a slope of 0.01 eV per day. For water, the trends were mostly similar with O(2), except that (1) the first exposure to water vapor showed small and large changes in I(0) (0.03 eV increase) and I(t) (0.4 eV decrease) and (2) the amplitudes of the mostly reversible change of I(0) (0.3 eV) and I(t) (0.05 eV) were much larger and smaller than those for O(2), respectively. A long-term decrease was also observed with a slope of 0.04 eV per day. These results indicate that the atmospheric effect by ambient air on I is mainly caused by water vapor, although oxygen also makes significant contribution. Since the observed trends are rather complex, there seem to be multiple factors affecting I, which is the energy difference between the vacuum level and the highest occupied molecular orbita. Possible microscopic mechanisms of the observed variation of I on these levels are also discussed in terms of the energy change in these levels.

リンク情報
DOI
https://doi.org/10.1063/1.2809360
CiNii Articles
http://ci.nii.ac.jp/naid/80017983168
Web of Science
https://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=JSTA_CEL&SrcApp=J_Gate_JST&DestLinkType=FullRecord&KeyUT=WOS:000251324900034&DestApp=WOS_CPL
ID情報
  • DOI : 10.1063/1.2809360
  • ISSN : 0021-8979
  • eISSN : 1089-7550
  • CiNii Articles ID : 80017983168
  • Web of Science ID : WOS:000251324900034

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