Presentation Information
[2P09]Electronic state and adsorption geometry of pentacene on reduced rutile-TiO2(110)
*Yuri Hasegawa1, Rintaro Hori2, Naoyuki Maejima2, Masaru Takizawa2 (1. University of Tsukuba, 2. Ritsumeikan University)
Pentacene is a widely used organic semiconductor whose molecular arrangement strongly affects (opto)electronic properties. On metals it lies flat, while on SiO2 it stands upright; however, studies on oxide substrates remain unclear. We examined pentacene on reduced rutile TiO2(110) using NEXAFS, UPS, and STM under UHV. The reduced surface, prepared by sputtering and annealing, showed a (1×1) Ti row structure with oxygen vacancies. STM revealed a lying-down pentacene monolayer with its long axis along [001], matching substrate asymmetry. Coverage dependence of NEXAFS reveals lying-down adsorption in the monolayer and increased tilt in multilayers. The π* features differed from gas-phase spectra, indicating adsorption-induced electronic changes. A 288 eV C=O peak appeared only on reduced surfaces, suggesting oxygen vacancies influence oxidation or electronic modification of molecule.