Detectivity, 219 flashlamp pumping

If we look at a few cases In the literature, we see a wide variation In the reported limiting noises [2A-27]. Table IV lists noises and detection limits for several laser systems. A flashlamp-pumped system, because of the relatively low Intensity and wide temporal pulse width, about 1 /is. Is limited by flame emission shot and flicker, which are temporally continuous noises. The... 

The Na + system has been chosen both for theoretical and experimental reasons. Ab initio potential energy surfaces are available /3/ and trajectory calculations are currently performed. CARS has been used to measure the state distribution of in photolysis /4/ and reaction dynamics /5/. Fig. 1 shows our experimei al setup. In a probe cell we produce a gas mixture of Na (550 K, 10 torr) and (10 to 1000 torr). A flashlamp-pumped dye laser (FLP) with variable pulselength excites sodium to the 3P-state. A CARS laser system detects the rovi-br gic population of hydrogen. Our present sensitivity is approximately 10 particles per cm and quantum state. With an adjustable time control the CARS laser system can monitor the requested population before, during or after the irradiation of the FLP-laser with a time resolution of 10 ns. 

Multiphoton ionization combined with mass spectroscopy has been proposed as a sensitive tool for analysis of trace gases to a detection limit of 2 parts in 10 . Flashlamp- and nitrogen-laser-pumped dye lasers have been used for REMPI detectors for gas chromatography. Aromatic hydrocarbons could be detected at the 10 pg level. The necessity for constant peak energy as well as CW power, for multiphoton ionization studies has been discussed. ... 

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