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Proceedings Paper

Infrared molecular binding spectroscopy realized in sorbent coated microfabricated devices
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Paper Abstract

Sorbent materials are utilized in a range of analytical applications including coatings for preconcentrator devices, chromatography stationary phases, and as thin film transducer coatings used to concentrate analyte molecules of interest for detection. In this work we emphasize the use of sorbent materials to target absorption of analyte vapors and examine their molecular interaction with the sorbent by optically probing it with infrared (IR) light. The complex spectral changes which may occur during molecular binding of specific vapors to target sites in a sorbent can significantly aid in analyte detection. In this work a custom hydrogen-bond (HB) acidic polymer, HCSFA2, was used as the sorbent. HCSFA2 exhibits a high affinity for hazardous vapors with hydrogen-bond (HB) basic properties such as the G-nerve agents. Using bench top ATR-FTIR spectroscopy the HFIP hydroxyl stretching frequency has been observed in the mid wave infrared (MWIR) to shift by up to 700 wavenumbers when exposed to a strong HB base. The amount of shift is related to the HB basicity of the vapor. In addition, the large analyte polymer-gas partition coefficients sufficiently concentrate the analyte in the sorbent coating to allow spectral features of the analyte to be observed in the MWIR and long wave infrared (LWIR) while it is sorbed to HCSFA2. These spectral changes, induced by analyte-sorbent molecular binding, provide a rich signal feature space to consider selective detection of a wide range of chemical species as single components or complex mixtures. In addition, we demonstrate an HCSFA2 coated microbridge structure and micromechanical photothermal spectroscopy to monitor spectral changes when a vapor sorbs to HCSFA2. Example ATR-FTIR and microbridge spectra with exposures to dimethylmethylphosphonate (DMMP – G nerve agent simulant) and other vapors are compared. In a generic form we illustrate the concept of this work in Figure 1. The results of this work provide the potential to consider compact detection systems with high detection fidelity.

Paper Details

Date Published: 21 May 2014
PDF: 7 pages
Proc. SPIE 9101, Next-Generation Spectroscopic Technologies VII, 910107 (21 May 2014); doi: 10.1117/12.2050819
Show Author Affiliations
R. Andrew McGill, U.S. Naval Research Lab. (United States)
Todd H. Stievater, U.S. Naval Research Lab. (United States)
Marcel W. Pruessner, U.S. Naval Research Lab. (United States)
Scott A. Holmstrom, Univ. of Tulsa (United States)
Kerry Nierenberg, Univ. of Tulsa (United States)
Rachel McGill, U.S. Naval Research Lab. (United States)
Viet Nguyen, U.S. Naval Research Lab. (United States)
Doewon Park, U.S. Naval Research Lab. (United States)
Christopher Kendziora, U.S. Naval Research Lab. (United States)
Robert Furstenberg, U.S. Naval Research Lab. (United States)


Published in SPIE Proceedings Vol. 9101:
Next-Generation Spectroscopic Technologies VII
Mark A. Druy; Richard A. Crocombe, Editor(s)

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