Nonlinear optics of surfaces and adsorbates. [P-nitrobenzoic acid]

Technical Report · Mon Nov 01 04:00:00 EST 1982

OSTI ID:6540239

Heinz, T F

In any material possessing a center of inversion, the process of optical second-harmonic generation (SHG) is forbidden within the electric-dipole approximation. As a consequence, the second-harmonic (SH) radiation produced by the excitation of two adjoining centrosymmetric media can arise largely from the few atomic layers of the interfacial region where the symmetry prevailing in the bulk is broken. This thesis presents a series of experiments exploring the influence of molecular adsorbates on SHG from such interfaces and evaluating the potential of this process as a surface-specific optical probe. Studies have been conducted on adsorption onto both metallic and insulating substrates. Formation of the first monolayer of AgCl on a silver electrode induced a 20-fold increase in SH output. Similar results have been observed for adsorbed pyridine and pyrazine molecules. In situ measurements of the equilibrium and transient behavior of pyridine adsorption on silver in an electrochemical environment have been made by means of SHG. For the case of molecules adsorbed on smooth, insulating substrates, the SHG technique has been extended along two lines, taking advantage of the spectral and tensorial properties of the nonlinearity of the interface. The former yields spectroscopic data on the adsorbate; the latter gives information on the adsorbate orientation. With a tunable pump laser, the position and lineshape of the S/sub 0/ ..-->.. S/sub 2/ electronic transition in rhodamine dye molecules adsorbed on fused silica have been recorded. The polarization dependences, which are specified by the tensor elements of the nonlinear susceptibility, proved helpful in the construction of a model of adsorption geometry. By a more refined experimental procedure and theoretical analysis, the orientation of p-nitrobenzoic acid adsorbed at a solid/liquid interface has also been determined from measurements of the SHG.

• Research Organization: Lawrence Berkeley Lab., CA (USA)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 6540239
• Report Number(s): LBL-15255; ON: DE83005929
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
400301 -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
400400 -- Electrochemistry
ADSORPTION
AMINES
AZINES
CARBOXYLIC ACIDS
CHALCOGENIDES
CHLORIDES
CHLORINE COMPOUNDS
DATA
DEPOSITION
DYES
ELECTRODEPOSITION
ELECTRODES
ELECTROLYSIS
ELEMENTS
ENERGY-LEVEL TRANSITIONS
EXCITATION
EXPERIMENTAL DATA
HALIDES
HALOGEN COMPOUNDS
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
INFORMATION
INTERFACES
LASERS
LYSIS
METALS
MINERALS
NITRO COMPOUNDS
NUMERICAL DATA
OPTICS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
ORIENTATION
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PYRAZINES
PYRIDINE
PYRIDINES
REAGENTS
RHODAMINES
SILICA
SILICON COMPOUNDS
SILICON OXIDES
SILVER
SILVER CHLORIDES
SILVER COMPOUNDS
SORPTION
SORPTIVE PROPERTIES
SURFACE COATING
SURFACE PROPERTIES
SURFACES
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS