35 methods, but most of these methods are implemented for nerve 36 agents mimics, and so there is no clear proof that they will work 37 for real CWA. 10 To complement the existing methodologies, 38 we have developed a series of new highly solvatochromic 39 fluorescent indicators for phosphorylating reagents capable of 40 developing large differences in fluorescence. In this paper, we 41 report our findings upon the selective fluorescent discrim-42 ination of real nerve agents from their mimics. 43 We have previously prepared some charge-transfer fluoro-44 genic probes, bearing conjugated donor and acceptor groups in 45 their structure, that were useful for the detection of significant 46 analytes. 11 For our current purpose we have designed new s1 47 fluorescent probes (Scheme 1).
48In this case, they have a secondary donor group that was not 49 involved in the charge-transfer process. Thus, the Suzuki
This paper presents the status of an ongoing development of a point detector for biological warfare agent sensing based on ultraviolet laser-induced fluorescence from single particles in air. The detector will measure the fluorescence spectra of single particles in a sheath flow air beam. The spectral detection part of the system consists of a grating and a photomultiplier tube array with 32 channels, which measure fluorescence spectra in the wavelength band from 300 nm to 650 nm. The detector is designed to measure laser induced fluorescence from single laser pulses and has been tested by measuring fluorescence from simulants of biological warfare agents in aqueous solution. The solutions were excited with laser pulses at the wavelengths of 293 nm and 337 nm. The paper also presents preliminary results on the sheath flow particle injector and time-resolved measurements of fluorescence from biological warfare agent simulants in solution.
The very low Raman scattering cross section and the fluorescence background limit the measuring range of Raman based instruments operating in the visible or infrared band. We are exploring if laser excitation in the middle ultraviolet (UV) band between 200 and 300 nm is useful and advantageous for detection of persistent chemical warfare agents (CWA) on various kinds of surfaces. The UV Raman scattering from tabun, mustard gas, VX and relevant simulants in the form of liquid surface contaminations has been measured using a laboratory experimental setup with a short standoff distance around 1 meter. Droplets having a volume of 1 µl were irradiated with a tunable pulsed laser swept within the middle UV band. A general trend is that the signal strength moves through an optimum when the laser excitation wavelength is swept between 240 and 300 nm. The signal from tabun reaches a maximum around 265 nm, the signal from mustard gas around 275 nm. The Raman signal from VX is comparably weak. Raman imaging by the use of a narrow bandpass UV filter is also demonstrated.
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