We developed AgClBr fibers that are flexible, non-hygroscopic, non-toxic and highly transparent in the mid-IR. A U-shaped AgClBr fiber was connected to an FTIR spectrometer, or a QCL, and its center was immersed in polluted water. In this setup fiber-optic evanescent wave spectroscopy (FEWS) made it possible to find out in a single measurement the chemical composition and concentration of a pollutant or a mixture of pollutants. This allowed us to monitor the water quality in real time and in a remote location (i.e. in field measurements) and determine whether it presents a health hazard. Using FEWS we monitored pollutants such as volatile organic compounds (VOC), in water, in concentrations of few ppb, as needed for environmental protection. We also monitored toxic pollutants, such as pesticides, in concentrations of few ppm, as needed for homeland security.
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