Enhanced Raman spectroscopy at dielectric interfaces

The examination of the merits of a new type of sampling structure for performing enhanced Raman scattering is presented here. These structures typically consist of 50 A of SiO$\sb2$ sputtered on Ag or Au island films, all coated on a lithographically defined opening in a masked SiO$\sb2$ substrate and use internal reflection in the SiO$\sb2$ substrate to excite plasma resonances in the island films with higher incident field strengths than possible with external excitation. Enhanced scattering from adsorbate molecules adsorbed on top of the SiO$\sb2$ overlayer is driven by the long ranged electromagnetic enhancement provided by the resonantly driven island film particles. Evidence for the long range enhancement comes from chemical passivation, scanning Auger, and distance dependence experiments, as well as comparing enhanced Raman scattering signals obtained from coated and uncoated Au island films. The dependence of the scattering on the excitation angle on incidence can be interpreted in terms of the strengths of the evanescent field components at the substrate-metal interface. Evidence suggesting that $p$-nitrobenzoic acid (PNBA) photodegrades to an azodibenzoate species when adsorbed on top of the SiO$\sb2$ overlayers as a result of laser illumination is obtained.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Chemistry, Analytical

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2011

Author dc:creator

• Walls, Dennis John

Contributors dc:contributor

• Bohn, Paul W.

• Chemistry, Analytical
• Chemistry, Physical

Statement dc:rights

• Copyright 1989 Walls, Dennis John

Language dc:language

eng

Identifier

AAI9011068
(UMI)AAI9011068

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/19349