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Anal Chem

Title:		Effective use of molecular recognition in gas sensing: results from acoustic wave and in situ FT-IR measurements
Author(s):		Hierlemann A; Ricco AJ; Bodenhofer K; Gopel W;
Address:		"Microsensor Research & Development Department, Sandia National Laboratories, Albuquerque, New Mexico 87185-1425, USA. hierlema@iqe.phys.ethz.ch"
Journal Title:		Anal Chem
Year:		1999
Volume:		71
Issue:		15
Page Number:		3022 - 3035
DOI:		10.1021/ac981311j
ISSN/ISBN:		0003-2700 (Print) 0003-2700 (Linking)
Abstract:		"To probe directly the analyte/film interactions that characterize molecular recognition in gas sensors, we recorded changes to the in situ surface vibrational spectra of specifically functionalized surface acoustic wave (SAW) devices concurrently with analyte exposure and SAW measurement of the extent of sorption. Fourier transform infrared external-reflectance spectra (FT-IR-ERS) were collected from operating 97-MHz SAW delay lines during exposure to a range of analytes as they interacted with thin-film coatings previously shown to be selective: cyclodextrins for chiral recognition, nickel camphorates for Lewis bases such as pyridine or organophosphonates, and phthalocyanines for aromatic compounds. In most cases where specific chemical interactions--metal coordination, 'cage' compound inclusion, or pi-stacking--were expected, analyte dosing caused distinctive changes in the IR spectra, together with anomalously large SAW sensor responses. In contrast, control experiments involving the physisorption of the same analytes by conventional organic polymers did not cause similar changes in the IR spectra, and the SAW responses were smaller. For a given conventional polymer, the partition coefficients (or SAW sensor signals) roughly followed the analyte fraction of saturation vapor pressure. These SAW/FT-IR results support earlier conclusions derived from thickness-shear mode resonator data"
Keywords:		"Acoustics Cyclodextrins/chemistry Equipment Design Gases/*analysis Indoles/chemistry Isoindoles Materials Testing Nickel/chemistry Spectroscopy, Fourier Transform Infrared/instrumentation/*methods Volatilization *gamma-Cyclodextrins;"
Notes:		"MedlineHierlemann, A Ricco, A J Bodenhofer, K Gopel, W eng Research Support, U.S. Gov't, Non-P.H.S. 1999/08/18 Anal Chem. 1999 Aug 1; 71(15):3022-35. doi: 10.1021/ac981311j"