2PPE-PEEM study on substrate mediated molecular excitaion

2014 Fiscal Year Final Research Report

• Project/Area Number: 25600004
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Nanostructural chemistry
• Research Institution: Osaka University
• Principal Investigator: MUNAKATA Toshiaki 大阪大学, 理学(系)研究科(研究院), 教授 (20150873)
• Project Period (FY): 2013-04-01 – 2015-03-31
• Keywords: ナノ材料 / ルブレン / グラファイト / 光励起 / 光電子分光 / 光電子放射電子顕微鏡

Outline of Final Research Achievements

Two-photon photoemission (2PPE) from rubrene films on graphite (HOPG) has been measured with a photoelectron emission microscope (PEEM) as functions of pump photon energy and coverage. The image potential state mediated excitation (J. Phys. Chem. C 2012, 116, 5821) is found to occur at specific areas (denoted as resonance areas) surrounded with areas of the uniform film of one monolayer (ML) coverage. The brightness of the resonance areas for sub-ML coverage shows clear resonance enhancement peaking at the pump photon energies of 4.4 eV. The area vanishes at coverage higher than 1 ML. The intensity profiles show that the resonance area is composed of bare graphite and nm-size clusters or isolated rubrene molecules. The specific area dominates the 2PPE process, exemplifying the significant role of defective areas in photoexcitation processes.

Free Research Field

表面化学