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

Koch, Norbert; Pop, D.; Weber, R.; Böwering, N.; Winter, Bernd; Wick, Markus; Leising, G.; Hertel, I. V.; Braun, W.

doi:10.1016/s0040-6090(01)00961-0

Cited by 46 publications

(57 citation statements)

References 36 publications

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“…97, 063112 ͑2010͒ optical light, thus increasing the conductivity by the creation of free charge carriers. 21 This effect is seen in the data of Figs. 3͑a͒ and 3͑c͒.…”

Section: -2mentioning

confidence: 70%

Photoswitching of azobenzene multilayers on a layered semiconductor

Iwicki

Ludwig

Kalläne

et al. 2010

Applied Physics Letters

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In situ photoelectron spectroscopy is used to study the adsorption and photoisomerization of azobenzene multilayers on the layered semiconductor HfS2 at liquid nitrogen temperatures. The measured valence band spectra indicate weak molecule–substrate coupling and provide evidence for reversible switching of azobenzene multilayers by light with different wavelengths. The photoswitching manifests itself in spectral shifts due to changes in the electrical surface conductance and in modifications of the electronic structure consistent with the results of outer valence Green’s function calculations. The photoemission results appear to establish azobenzene as an optoelectrical molecular switch.

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“…97, 063112 ͑2010͒ optical light, thus increasing the conductivity by the creation of free charge carriers. 21 This effect is seen in the data of Figs. 3͑a͒ and 3͑c͒.…”

Section: -2mentioning

confidence: 70%

Photoswitching of azobenzene multilayers on a layered semiconductor

Iwicki

Ludwig

Kalläne

et al. 2010

Applied Physics Letters

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“…As described earlier [1,19], the laser power was incrementally increased until the HOMO peak position and width remained constant upon further increase in laser power. This saturation was reached here at 14 mW (nominal laser power).…”

Section: Organic Single Crystalsmentioning

confidence: 97%

“…Angle-resolved ultraviolet photoelectron spectroscopy with synchrotron radiation excitation is established as the most powerful tool for probing the energy band structure of solids. However, the band structure measurement of (single crystalline) organic semiconductors is difficult due to their low conductivity on one hand and the low tolerance of conjugated organic compounds towards beam damage on the other hand [19]. Positive charging near the surface of the organic specimen due to the photoemission process causes electric fields that distort or even suppress a meaningful photoemission spectrum.…”

Section: Introductionmentioning

confidence: 99%

Two dimensional band structure mapping of organic single crystals using the new generation electron energy analyzer ARTOF

Vollmer

Ovsyannikov

Gorgoi

et al. 2012

Journal of Electron Spectroscopy and Related Phenomena

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Two dimensional band structure mapping of organic single crystals using the new generation electron energy analyzer ARTOF. Spectroscopy and Related Phenomena, Journal of Electron AbstractWe report on a novel type of photoemission detector, the Angle Resolved Time Of Flight electron energy analyzer (ARTOF), which enables electronic band structure determination under measurement conditions that are ideal for radiation-sensitive samples. This is facilitated through the combination of very high electron transmission and wide accessible angular range in one geometry. These properties make the ARTOF predestined to investigate specimens that strongly suffer from radiation damage during photoemission experiments under "standard"conditions, such as organic single crystals, as extremely low fluxes can be used while not compromising spectra accumulation times and signal-to-noise ratio. Even though organic single crystals are of increasing fundamental and applied scientific interest, knowledge of their electronic properties is still largely based on theoretical calculations due to major experimental challenges in measuring photoemission. In this work we show that the band structures of rubrene and tetracene single crystals can be obtained with unprecedented quality 2 using the ARTOF detector. The dispersion of the highest occupied band in rubrene is confirmed in accordance with an earlier report [1] and we disclose the absence of notable dispersion for the highest occupied energy level in the tetracene single crystal.

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“…From conjugated -electron systems such irradiation effects are well known and were attributed to the generation of structural and chemical defects, i.e., bond breaking and/or cross linking. 43 These defects hinder the formation of delocalized molecular orbitals and thus affect first the corresponding states close to E F .…”

Section: Vuv-radiation-induced Surface Damagementioning

confidence: 99%

Surface characterization and surface electronic structure of organic quasi-one-dimensional charge transfer salts

et al. 2003

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We have thoroughly characterized the surfaces of the organic charge-transfer salts TTF-TCNQ and (TMTSF) 2 PF 6 which are generally acknowledged as prototypical examples of one-dimensional conductors. In particular x-ray-induced photoemission spectroscopy turns out to be a valuable nondestructive diagnostic tool. We show that the observation of generic one-dimensional signatures in photoemission spectra of the valence band close to the Fermi level can be strongly affected by surface effects. Especially, great care must be exercised taking evidence for an unusual one-dimensional many-body state exclusively from the observation of a pseudogap.

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

Cited by 46 publications

References 36 publications

Photoswitching of azobenzene multilayers on a layered semiconductor

Photoswitching of azobenzene multilayers on a layered semiconductor

Two dimensional band structure mapping of organic single crystals using the new generation electron energy analyzer ARTOF

Surface characterization and surface electronic structure of organic quasi-one-dimensional charge transfer salts

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