Hole-vibration coupling of the highest occupied state in pentacene thin films

• Published in: Physical review. B, Condensed matter and materials physics Condensed matter and materials physics, 2005-10, Vol.72 (15), p.153412.1-153412.4, Article 153412
• Main Authors: YAMANE, H, NAGAMATSU, S, FUKAGAWA, H, KERA, S, FRIEDLEIN, R, OKUDAIRA, K. K, UENO, N
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electron and ion emission by liquids and solids; impact phenomena; Electron states and collective excitations in multilayers, quantum wells, mesoscopic, and nanoscale systems; Electron states and collective excitations in thin films, multilayers, quantum wells, mesoscopic and nanoscale systems; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Exact sciences and technology; Photoemission and photoelectron spectra; Physics; TECHNOLOGY; TEKNIKVETENSKAP
• ISSN: 1098-0121; 1550-235X; 1550-235X
• DOI: 10.1103/physrevb.72.153412

The hole-vibration coupling of the highest occupied state in pentacene thin films on graphite is studied by high-resolution ultraviolet photoelectron spectroscopy. Vibration satellites in the film show a take-off-angle dependence, indicating that the Franck-Condon principle is not strictly satisfied in this system. They are more intense than in the gas phase and the vibrational energy in the film is slightly lower than that in the gas phase. This demonstrates that the reorganization energy in pentacene thin films is slightly larger than that estimated from the photoelectron spectrum of free pentacene molecules. Furthermore, it is pointed out that the electron hopping in the low-temperature film may occur in the femtosecond scale before the electronic polarization of the surrounding medium is completed. © 2005 The American Physical Society.