Trapping, radiative

The useful range over which LIFS can be used to measure the number density of some excited state is determined at the low end by noise and uncertainty considerations and at the high end by radiative trapping effects. 

Equation 31 is used to determine the smallest concentration of a species that can be detected. The dynamic range of the instrument will then be determined by the effects of radiative trapping at large number densities. 

Radiative Trapping. The radiative trapping problem is illustrated in Figure 6. 

Figure 7. Radiative trapping of sodium in a methane-air flame...

The detectability limit for any given measurement is defined in terms of measurement uncertainty and for LIFS can be quite small. This limit, however, can be affected by interferences of various kinds and care must be taken in instrument design to avoid difficulties. The dynamic range for LIFS is generally controlled by radiative trapping effects. 

Hofkens J, Schroeyers W, Loos D, et al. Triplet states as non-radiative traps in multi-chromophoric entities single molecule spectroscopy of an artificial and natural antenna system. Spectrochim Acta 2001 A57 2093-107. 

The direct and infrared radiations at the surfaces are calculated to take into account the shadowing and radiative trapping effects of the buildings. 

The isomorphism between the radiative trapping force [Eq. (109)] and the electrostatic force [Eq. (Ill)] allows to characterize the coefficient AT [Eq. (110)] in terms of an effective charge for the specification of the radiative trapping force... 

Ideally, PPV should exhibit a thoroughly r-conjugated structure for electronic applications. In practice, this cannot be achieved. Saturated defects interrupt the tr-conjugated structure and thus the length of conjugation. On the other hand, ethynylene moieties instead of vinylene moieties may act as traps of charge carriers. The trapping may occur at either radiative or non-radiative trap states. In fact, there are two types of defects ... 

The enhancement of Eu(III) luminescence in glasses can be also achieved by embedding small silver particles (Malta et al., 1985) in the glass. The question whether the enhancement is due to interaction of the silver plasmons with the medium, or due to radiative trapping of Eu(III) luminescence is still disputable. 

Jg+l) elements. In general, therefore, (2J +1) different parameters would be necessary to describe the relaxation of the system in the presence of collisions, radiative trapping etc. Fortunately, however, in resonance fluorescence ex-... 

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