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Raman spectroscopy has become a potent chemical imaging technique with recent advances in liquid crystal tunable filter (LCTF)-based spectrometers and multispectral image processing. Chemical imaging is used in investigating molecular structure by developing a standard analytical procedure. In LCTF Raman imaging, spatially-resolved analyte spectra within complex host matrices are collected. These spectra can be processed without the need for stains, dyes or contrast agents to produce image contrasts.

Abstract: Based on the chemical reaction of silver nanoparticles (Ag NPs) with hydrogen sulfide (H2S), an optical sensor to detect H2S gas at room temperature was designed. Peak intensity of localized surface plasmon resonance (LSPR) absorption of Ag NPs was monitored as the sensor responded to H2S. The fabricated Ag NP films were very sensitive to the presence of H2S with a gas concentration in the parts per million by volume (ppmv) range. The reaction of H2S on silver nanoparticle surfaces proceeded very quickly, as indicated by a significant and rapid decrease in the peak absorbance of LSPR. From analysis of the reaction kinetics, the initial reaction between Ag NPs and H2S gas was revealed to be a first-order reaction in Ag, and the initial reaction rate was proportional to the gas concentration in the ppmv range. The H2S gas concentration can be determined from either the initial reaction rate or from the H2S dose measured after extended reaction periods. Performance of the Ag NP film as a dosimeter at ambient conditions was evaluated by exposure to H2S in air, to water vapor with different relative humidity, to ammonia, to hydrochloric acid and to some volatile organic compound vapors. [Copyright &y& Elsevier]

The article presents information on archaeological research conducted in 2010 by students from Ohio State University. They excavated the Fort Center site, located in Glades County, Florida. Information on the methodology they used in their fieldwork is presented, and a discussion of their findings is included.