Laser probing spatially precise

Spatially Precise Laser Diagnostics for Practical Combustor Probing... 

Eckbreth, A. C. "Spatially Precise Laser Diagnostics for Practical Combustor Probing," Presented at the 178th ACS National Meeting, Washington, D.C., September 10-14, 1979. 

Table 1 summarizes the capabilities of laser and ion microprobe analysis in comparison to the time-honored conventional techniques. Figure 1 shows the advantages and trade-offs involved in the newer techniques spatial resolution vs. accuracy and precision vs. cost of analysis. These factors will be discussed further under Microanalysis. Continuous flow mass-spectrometry (Merritt and Hayes 1994) IR-spectroscopy (Kerstel et al. 1999, Esler et al. 2000) large radius, multi-collector ion probes (McKeegan and Leshin, this volume) automation and shorter wavelength ElV lasers (Young et al. 1998, Farquhar and Rumble 1998, Fiebig et al. 1999, Jones et al. 

In monochromatic two-photon photoemission, only one photon energy is used (Hva = hvi), which leads to some special effects. The most simple reahzation of the experiment is the use of only one laser pulse. In this case, the optimum temporal and spatial overlap is intrinsically ensured. If the laser beam is spHt and overlapped with a controllable time delay, the cross correlation (= autocorrelation) is symmetric and the distinction between pump and probe pulses becomes meaningless. For identical polarization of the two photon beams, the autocorrelation is dominated by interference effects, which permits a very precise determination of the time delay [29]. 

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