期刊
JOURNAL OF PHYSICAL CHEMISTRY A
卷 113, 期 16, 页码 4581-4586出版社
AMER CHEMICAL SOC
DOI: 10.1021/jp8112649
关键词
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资金
- National Science Foundation [EEC-0647560, CHE-0414554, BES-0507036]
- DTRA JSTO Program [FA9550-06-1-0558]
- AFOSR/DARPA Project [FA9550-08-1-0221]
- NSF MRSEC [DMR-0520513]
- Ruth L. Kirschstein National Research Service Award [5 F32 GM077020]
A chemical warfare agent (CWA) gas detector based on surface-enhanced Raman spectroscopy (SERS) using robust nanostructured substrates and a portable Raman spectrometer is a promising alternative to existing modalities. A gas-dosing apparatus was constructed to simulate chemical gas exposure and provide a platform for quantitative analysis of SERS detection. As a first step toward characterizing SERS detection from the gas phase, benzenethiol (BT) has been chosen as the test analyte. SERS spectra were monitored during BT adsorption onto a silver film over a nanosphere (AgFON) substrate. The SERS detection limit time (DLt) for BT on a AgFON at 356 K is found to be 6 ppm-s (30 mg-s m(-3)) for a data acquisition time (t(acq)) of 1 s. The DLt for this kinetically controlled sensor is fundamentally determined by the low sticking probability of BT on AgFONs which is determined to be similar to 2 x 10(-5) at 356 K. The sticking probability increases with increasing temperature consistent with an adsorption activation barrier of similar to 13 kJ mol(-1). Although the DLts found in the present study for BT are in the low ppm-s, a theoretical model of SERS detection indicates DLts below 1 ppb s(-1) for t(acq) = 1 s are, in fact, achievable using existing portable Raman instrumentation and AgFON surfaces. Achieving this goal requires the sticking probability be increased 3 orders of magnitude, illuminating the importance of appropriate surface functionalization.
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