123rd General Meeting of the KCS

Type Oral Presentation
Area Oral Presentation for Young Physical Chemists I
Room No. Room 305+306
Time THU 09:30-09:39
Code PHYS1.O-4
Subject Highly efficient, mode-specific vibrational excitation of organic-molecules by plasmon-induced electrons
Authors Hyun-Hang Shin, Zee Hwan Kim*
Department of Chemistry, Seoul National University, Korea
Abstract We observed abnormally intense anti-Stokes SERS peak of symmetric NO stretching (νNO) of 4-nitrobenzenethiol (NBT) molecules placed at plasmonic gaps. Corresponding effective vibrational temperatures are found to be 550 K. Such vibrational excitation occurs during the early stage of photo-reduction of NBT, whereas non-reactive aromatic thiols with similar structures (such as 4-mercaptobenzonitrle, 4-methylbenzenethiol) do not show any sign of vibrational excitation. This mode-spedific excitation is successfully reproduced by inelastic resonant scattering of electrons ejected from the metallic surface. The chemical specificity of the events and local field dependence of anti-Stokes νNO intensity strongly support our modelling also. Furthermore, wavelength dependence of the anti-Stokes νNO intensity indicates that the electron originates from the excitation of localized surface plasmons of nanostructures.
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