Resonant background

Note Units are the equivalent signal from 1 X 106 HO molecules per cubic centimeter ambient the symbol + indicates positive interference from spurious HO, and indicates a negative interference. Gross resonant background is the sum of backgrounds with and without isobutane values for single-pass (80) and multipass (80, 103) measurements were 10, 78, and 63, respectively. NA, not available. 

Figure 18. Spin temperature Ts obtained by inversion of (6) where M ) is given by the magnetization curves of Fig. 16. The resonant absorption near 0.491 T is superimposed to a non-resonant background absorption corresponding to a nearly constant spin-temperature.

Many variants of the experiment described in figure 8.1 have been performed, and we shall encounter some of them later in this chapter. Perhaps the most important variant is that it is often possible to arrange the state selection so that resonant transitions result in an increase in the detected beam flux, ideally against a very low off-resonance background. This is known as the flop-in mode of detection, and it can be very sensitive. Again we shall meet examples of this later. 

Eckbreth, A. C., and Hall, R. J. "CARS Concentration Sensitivity with and without Non-Resonant Background Suppression." Combustion Science and Technology 25 (1981) 175. 

The fourth detector system is to use a resonance scintillation counter [57]. A standard type of plastic scintillator for /5-detection is doped with the resonant absorber. It is insensitive to the non-resonant background of primary... 

A major difference between SFG and other surface vibrational spectroscopy techniques is the presence of a non-resonant background, because, in part, of the metal substrate. This background is usually treated as independent of the frequency and characterized as a constant ( nr). although this treatment is not always possible. In electrochemical systems, /nr is not usually independent of the applied potential. This is because of potential-dependent changes in the electronic state... 

The factor has been included to account for the difference in population between the lower state (usually the ground state) and the excited vibrational state thus app aches unity at low temperature and zero at high temperature. The term % has been added to describe the non-resonant background from other Raman transitions. 

SRG Induced amplification of 0)2 Modulation of Increase in intensity of 0)2 when 0) —0)2 = tt>Raman No phase matching, no non-resonant background, linear with concentration Sensitivity limited by stability of probe laser, difficult to multiplex... 

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