Experimental examination of ultraviolet Raman cross sections of chemical warfare agent simulants

Abstract

Laser induced Raman scattering from the commonly used chemical warfare agent simulants dimethyl sulfoxide, tributyl phosphate, triethyl phosphonoacetate was measured at excitation wavelengths ranging from 210 to 410 nm using a pulsed laser based spectrometer system with a probing distance of 1.4 m and with a field of view on the target of less than 1mm. For the purpose of comparison with well explored reference liquids the Raman scattering from simulants was measured in the form of an extended liquid surface layer on top of a silicon wafer. This way of measuring enabled direct comparison to the Raman scattering strength from cyclohexane. The reference Raman spectra were used to validate the signal strength of the simulants and the calibration of the experimental set up. Measured UV absorbance functions were used to calculate Raman cross sections. Established Raman cross sections of the simulants make it possible to use them as reference samples when measuring on chemical warfare agents in droplet form.

Nanophotonic waveguides for chip-scale raman spectroscopy: Theoretical considerations

“…The Raman scattering cross-section for this DMSO line can be interpolated from the value found using a visible pump: σ ≈ 3.3 × 10 −33 m 2 . 6 Combining these values with the waveguide parameters of β = 0.0041 (Fig. 2a) and L = 9.6 mm, we obtain η ≈ 7.8 × 10 −13 .…”

Ultraviolet Raman scattering from persistent chemical warfare agents

“…A tunable pulsed UV laser (NT342B from Ekspla) and a spectrometer (Shamrock SR-500i-B1 spectrograph with a DH334T-18U-E3 ICCD from Andor) are the basic parts of the instrumen-ICCD camera spectrograph *777 _;:#7 tation. The scattered Raman radiation is collected from above the target to within a solid angle of about 0.05 sr which is almost 10 times more than in our previous setup [4]. This is achieved by the use of a pair of achromatic lenses, 4.5 cm from the target set to provide a 1:1 image of the surface onto the fiber.…”

“…Measured UV Raman spectra from VX have appeared relatively weak compared to other agents in our previous work and it was not possible to faithfully reproduce VX spectra due to limitations in the experimental procedure [4]. The main objective of this study is to acquire sufficiently strong UV Raman signals for V-agents to be able to discern clear spectra and estimate Raman cross sections as a function of laser wavelength.…”

Raman Scattering Techniques for Defense and Security Applications

“…Owing to their extreme toxicity, much of the work on CWAs has been conducted on simulant chemicals with similar molecular features, such as organophosphates or on the hydrolysis products of these materials. ,,,− It is worth noting that many of simulants used are the same as the hydrolysis products. As such, they remain valuable detection targets in their own right, with the potential to act as markers of the release of CWAs.…”