Near IR Scanning Angle Total Internal Reflection Raman Spectroscopy at Smooth Gold Films

Thumbnail Image
Supplemental Files
Date
2012-04-13
Authors
McKee, Kristopher
Meyer, Matthew
Major Professor
Advisor
Committee Member
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract

Total internal reflection (TIR) Raman and reflectivity spectra were collected for nonresonant analytes as a function of incident angle at sapphire or sapphire/smooth 50 nm gold interfaces using 785 nm excitation. For both interfaces, the Raman signal as a function of incident angle is well-modeled by the calculated interfacial mean square electric field (MSEF) relative to the incident field times the thickness of the layer being probed in the Raman measurement (DRS). The Raman scatter was reproducibly enhanced at the interface containing a gold film relative to the sapphire interface by a factor of 4.3−4.6 for aqueous pyridine or 2.2−3.7 for neat nitrobenzene, depending on the analyzed vibrational mode. The mechanism for the increased Raman signal is the enhanced MSEF at incident angles where propagating surface plasmons are excited in the metal film. The background from the TIR prism was reduced by 89−95% with the addition of the gold film, and the percent relative uncertainty in peak area was reduced from 15 to 1.7% for the 1347 cm−1 mode of nitrobenzene. Single monolayers of benzenethiol (S/N = 6.8) and 4-mercaptopyridine (S/N = 16.5) on gold films were measured by TIR Raman spectroscopy with 785 nm excitation (210 mW) without resonant enhancement in 1 min.

Series Number
Journal Issue
Is Version Of
Versions
Series
Academic or Administrative Unit
Type
article
Comments

Reprinted (adapted) with permission from Analytical Chemistry, 84(10); 4300-4306. Doi: 10.1021/ac203355a. Copyright 2012 American Chemical Society.

Rights Statement
Copyright
Sun Jan 01 00:00:00 UTC 2012
Funding
DOI
Supplemental Resources
Collections