Photoemission and Thermal Desorption Studies of Electron Beam Polymerized Thiophene Films on Pt(111)

We report on the investigation of electron beam induced modifications of thin films (on the order of a few monolayers) of thiophene adsorbed on Pt(l 1 1). X-ray and ultraviolet photoelectron spectroscopy have been used to characterize the growth and thermal behavior of these thin films upon electron...

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Bibliographic Details
Main Authors: Land, Terry A, Hemminger, John C
Format: Report
Language:English
Subjects:
ANNEALING
Atomic and Molecular Physics and Spectroscopy
BEHAVIOR
CONTRAST
ELECTRON BEAMS
INTERACTIONS
IRRADIATION
MATERIALS
MODIFICATION
OLIGOMERS
PHOTOELECTRIC EMISSION
PHOTOELECTRONS
PLATINUM
POLYMERIZATION
POLYMERS
Radiation and Nuclear Chemistry
RINGS
SPECTRA
THIN FILMS
THIOPHENES
X RAY PHOTOELECTRON SPECTROSCOPY
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Summary:We report on the investigation of electron beam induced modifications of thin films (on the order of a few monolayers) of thiophene adsorbed on Pt(l 1 1). X-ray and ultraviolet photoelectron spectroscopy have been used to characterize the growth and thermal behavior of these thin films upon electron beam irradiation. These films show characteristics that are consistent with electron beam induced polymerization. Upon electron beam modification there is a broadening of all peaks in the UPS spectra which is attributed to the delocalization of electrons due to increased interaction between aromatic rings. XPS and UPS spectra show changes that parallel growth of a polymer, as observed for thiophene oligomers and, exhibit the same spectral features that are reported in the literature for electrochemically grown films (1000 Anstrom) of polythiophene. In addition to spectral changes, one would expect polymerization to create changes in the behavior of the material as well. In comparing the behavior with annealing of the unmodified thiophene, with that of the electron beam modified thiophene, we find dramatic differences. At 234 K unmodified thiophene exhibits loss of the multilayer and by 340 K is decomposed. In contrast, the beam modified thiophene does not show a loss of material with annealing, and retains its intact character even at elevated temperatures (600 K). The changes observed in the XPS and UPS spectra of thin thiophene films are consistent with electron beam polymerization.