Abstract

This paper describes a compact and rugged Raman integrated tunable sensor coupled with surface-enhanced Raman scattering substrates for the screening of a wide variety of chemical and biological agents for homeland defense applications. The field-deployable instrument, consisting of an 830-nm diode laser for excitation and an avalanche photodiode (APD) for detection, is a fully integrated, tunable, “point-and-shoot” Raman device based on solid-state acousto-optic tunable filter (AOTF) technology. It can provide direct identification of chemical and biological samples in a few seconds under field conditions. This paper illustrates some applications of this portable device for the detection of various compounds of particular interest for homeland defense applications. These include methyl parathion (a nerve agent simulant) and dipicolinic acid (a biomarker for bacillus endospore), and other chemical warfare simulants such as dimethyl methylphosphonate, pinacolyl methylphosphonate, diethyl phosphoramidate, and 2-chloroethyl ethylsulfide, which are simulants for sarin (GB), soman (GD), tabun (GA), and sulfur mustard (HD), respectively, and intact bacteria such as Bacillus globigii, Erwinia herbicola, and Bacillus thuringiensis, which are simulants for biological warfare agents.

Keywords: Sensors; Surface-enhanced Raman scattering; Chemical warfare agent; Biological warfare agent; Acousto-optic tunable filter (AOTF)

Article Outline

1. Introduction

2. Experimental

2.1. Chemicals and materials

2.2. Preparation of surface-enhanced Raman scattering substrates

2.2.1. Silver nanoparticle island films

2.2.2. Silver colloids

2.2.3. Silver-oxide thin films and silver nanoclusters

2.3. Instrument

3. Results and discussion

3.1. Surface characterization of SERS substrates

3.2. Construction of portable Raman integrated tunable sensor

3.3. Detection of chemical and biological warfare simulants

4. Conclusions

Acknowledgements

References

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