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Proceedings Paper

Second Harmonic Generation Probe Of Adsorbate Structural Transition And Energy Transfer Dynamics On A Metal Surface
Author(s): L E Urbach; D. Heskett; J M. Hicks; K. J. Song; E W Plummer; H L Dai
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Paper Abstract

Second Harmonic Generation (SHG) has many advantages as a diagnostic tool for use in studying processes which occur at surfaces. It can be used to study surface properties of the substrate itself, or those processes which involve adsorbed molecular layers. These advantages include: 1) fast time resolution, since the SHG occurs only in the presence of the light, and laser pulses as short as the femtosecond time scale can be used for SHG. 2) frequency resolution. Electronic and vibrational transitions can be resolved through resonantly enhanced SHG with 0.1 meV resolution using tunable lasers from the IR to UV region. 3) surface sensitivity, since, in the dipole approximation, SHG is only generated at the surface or interfacial region of a centro-symmetric material. It has been shown that the surface SHG is sensitive to submonolayer adsorbate coverages and to surface structural changes.2 4) nonintrusiveness. The light intensity required for SHG is usually far below the damage threshold of the surface and is low enough to avoid significant heating of the adsorbate/substrate system. The frequency of the light can be chosen to avoid any resonant absorption by either the adsorbate or the substrate. Thus no specific excitations will perturb the system under study. 5) in situ diagnosis. A surface process can be probed directly on the surface by SHG as it proceeds. The system can be a clean surface, or a surface with submonolayer or multilayer adsorbates.

Paper Details

Date Published: 15 August 1989
PDF: 11 pages
Proc. SPIE 1056, Photochemistry in Thin Films, (15 August 1989); doi: 10.1117/12.951620
Show Author Affiliations
L E Urbach, University of Pennsylvania (United States)
D. Heskett, University of Pennsylvania (United States)
J M. Hicks, University of Pennsylvania (United States)
K. J. Song, University of Pennsylvania (United States)
E W Plummer, University of Pennsylvania (United States)
H L Dai, University of Pennsylvania (United States)


Published in SPIE Proceedings Vol. 1056:
Photochemistry in Thin Films
Thomas F. George, Editor(s)

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