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Title: Non-linear optical studies of adsorbates: Spectroscopy and dynamics

In the first part of this thesis, we have established a systematic procedure to apply the surface optical second-harmonic generation (SHG) technique to study surface dynamics of adsorbates. In particular, we have developed a novel technique for studies of molecular surface diffusions. In this technique, the laser-induced desorption with two interfering laser beams is used to produce a monolayer grating of adsorbates. The monolayer grating is detected with diffractions of optical SHG. By monitoring the first-order second-harmonic diffraction, we can follow the time evolution of the grating modulation from which we are able to deduce the diffusion constant of the adsorbates on the surface. We have successfully applied this technique to investigate the surface diffusion of CO on Ni(111). The unique advantages of this novel technique will enable us to readily study anisotropy of a surface diffusion with variable grating orientation, and to investigate diffusion processes of a large dynamic range with variable grating spacings. In the second part of this work, we demonstrate that optical infrared-visible sum-frequency generation (SFG) from surfaces can be used as a viable surface vibrational spectroscopic technique. We have successfully recorded the first vibrational spectrum of a monolayer of adsorbates using optical infrared-visible SFG. Themore » qualitative and quantitative correlation of optical SFG with infrared absorption and Raman scattering spectroscopies are examined and experimentally demonstrated. We have further investigated the possibility to use transient infrared-visible SFG to probe vibrational transients and ultrafast relaxations on surfaces. 146 refs.« less
Authors:
Publication Date:
OSTI Identifier:
5538721
Report Number(s):
LBL-27694
ON: DE90001543; TRN: 89-026045
DOE Contract Number:
AC03-76SF00098
Resource Type:
Technical Report
Resource Relation:
Other Information: Thesis (Ph.D.)
Research Org:
Lawrence Berkeley Lab., CA (USA)
Sponsoring Org:
DOE/ER
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; SURFACES; NONLINEAR OPTICS; ADSORPTION; CARBON MONOXIDE; CRYSTALS; DIFFUSION; DYNAMICS; EXCITATION; GRATINGS; MOLECULES; NICKEL; SPECTROSCOPY; SURFACE PROPERTIES; VIBRATIONAL STATES; CARBON COMPOUNDS; CARBON OXIDES; CHALCOGENIDES; ELEMENTS; ENERGY LEVELS; ENERGY-LEVEL TRANSITIONS; EXCITED STATES; MECHANICS; METALS; OPTICS; OXIDES; OXYGEN COMPOUNDS; SORPTION; TRANSITION ELEMENTS 656002* -- Condensed Matter Physics-- General Techniques in Condensed Matter-- (1987-)