Resonance fluorescence signal, ratio

Figure 9. Ratio of Rayleigh to resonance fluorescence signal (Cl is the Rabi frequency at Cl — 1 A the radiation density is — 8 X JO 17 J/m3).

Chemical Conversion Methods. Laser-Induced and Resonance Fluorescence of HO. Considerable effort has been applied to the measurement of HO in the stratosphere and troposphere. Ultraviolet fluorescence techniques based on lasers or resonance lamps have received a great deal of attention and study. Because HO concentrations are typically factors of one-tenth to one-hundredth those of H02 in the atmosphere, the difficulties associated with making HO measurements by using fluorescence [low signal-to-noise ratio, laser-generated HO, background fluorescence, etc. see the... 

The seed is selectively and sequentially pumped with a light source at two wavelengths and the non-resonant fluorescence is observed in each case. The ratio of the two fluorescence signals is related to the temperature. The method was first demonstrated by Haraguchi, et al. (27), who measured temperatures in a variety of flames and whose work has been extended by... 

As especially in the case of non-resonant AFS the fluorescence intensities are low, special precautions have to be taken for signal acquisition. Indeed, the signal-to-noise ratios can be improved considerably by using pulsed signals and phase-sensitive amplification, as is easily done e.g. in the case of laser sources (see Section 2.1). 

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