Radiation induced degradation and surface charging of organic thin films in ultraviolet photoemission spectroscopy

Citation
N. Koch et al., Radiation induced degradation and surface charging of organic thin films in ultraviolet photoemission spectroscopy, THIN SOL FI, 391(1), 2001, pp. 81-87
Citations number
39
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science","Material Science & Engineering
Journal title
THIN SOLID FILMS
ISSN journal
0040-6090 → ACNP
Volume
391
Issue
1
Year of publication
2001
Pages
81 - 87
Database
ISI
SICI code
0040-6090(20010702)391:1<81:RIDASC>2.0.ZU;2-2
Abstract
The effect of vacuum ultraviolet radiation on the: valence electronic struc ture of the electroluminescent organic materials p-sexiphenyl (6P) and tris -(8-hydroxy quinoline) aluminum (Alq(3)) was investigated by ultraviolet ph otoemission spectroscopy (UPS). The intense radiation of an undulator at th e storage ring BESSY II (Berlin) caused a loss of conjugation in 6P, eviden ced by a decrease in intensity of delocalized pi -orbitals in the UPS spect ra. Depending on the degree of film degradation, surface charging was obser ved for both materials. It is shown that by illuminating the sample with la ser light that can be absorbed by the organic/metal substrate system the su rface charging could be compensated. Thus, the generation of free charge ca rriers by optical means appears to be a useful substitute for the use of an electron flood-gun in photoemission experiments, whenever sensitive sample s could suffer from irradiation with electrons. (C) 2001 Elsevier Science B .V. Ah rights reserved.