Regensburg 2019 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 8: Metal Substrates I: Adsorption and Reactivity
O 8.6: Vortrag
Montag, 1. April 2019, 11:45–12:00, H25
Real-space observation of far- and near-field-induced photolysis of molecular oxygen on a Ag(110) surface by visible light — •Chenfang Lin1 and Takashi Kumagai1,2 — 1Department of Physical Chemistry, Fritz-Haber Institute of the Max-Planck Society, Faradayweg 4-6, 14195 Berlin, Germany — 2JST-PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012, Japan
Dissociation of molecular oxygen is an important elementary process in heterogeneous catalysis. Recently, it has been demonstrated that photo-induced dissociation of molecular oxygen can be significantly enhanced using plasmonic Ag nanoparticles and occurs even by visible light via excitation of surface plasmons [1,2]. Here we report the direct observation of oxygen photolysis at low coverages (0.01 monolayer) by far- and near-field excitation in the visible range by using a combination of an STM and a wavelength-tunable laser. It is found that the cross section for the far-field excitation (about 10−19 cm2) can be largely enhanced in a plasmonic STM junction with an Ag or Au tip. We also demonstrate that the wavelength dependence of the oxygen photolysis can be tuned by nanoscale fabrication of an STM tip with focused ion beam milling. Our approach provides a unique opportunity to investigate the optimal nanostructures for plasmonic catalysts.
[1] Phillip Christopher, Hongliang Xin and Suljo Linic, Nature Chemistry 3, 467-472 (2011)
[2] Phillip Christopher, Hongliang Xin, Andiappan Marimuthu and Suljo Linic, Nature Materials 11, 1044-1050 (2012)