Three-dimensions demonstration analysis

Detection and identification of chemical warfare simulants based on multidimensional phase shaped femtosecond laser pulses coupled to mass spectrometry (MS) is demonstrated. The presented approach is based on binary phase shaping (BPS) and aims to improve the accuracy and precision required for security applications. It is based on multiphoton intrapulse interference of femtosecond laser pulses. Spectra retrieved by applying n-differently shaped pulses represent n-dimensions of the analysis. We present a multidimensional technique for detection and identification of analogues to chemical agents and mixtures in real-time. Experimental results for dimethyl phosphate, pyridine, and three isomers of nitrotoluene are presented. 

Fig. 7. Energy analysis by the retarding potential technique of argon primary ions produced in a standard mass-spectrometer ion source operated with a dc repeller field. The shape of the curve should be independent of the ion exit energy E data shown for three different values of E demonstrate this in the appropriately normalized plot. The distribution of experimental ion exit energies results from the finite thickness of the electron beam, and the figure shows theoretical distributions predicted for various assumed thicknesses of the electron beam. Fair agreement is found for an assumed thickness of 0.5 mm, the actual dimension of the slit through which the electron beam enters the source.

The second system is the thin liquid films (45-90A) of a nearly spherical, nonpolar molecule, tetrakis(2-ethylhexoxy) silane. The XR analysis demonstrated direct monitoring of internal layering in the thin liquid films. Model-independent fitting to the XR data found that there are three electron density oscillations near the solid-liquid interface, with a period of 10A (consistent with the molecular dimensions). The oscillation amplimde has a strong inverse dependence on the substrate surface roughness. 

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