Cross-section for quenching

Considerable effort has been devoted to the determination of cross-sections for quenching of fluorescence from some of the lower states, but apart from the first two excited states zz IIj and A2h+, little attention has been paid to their photochemistry. 

Fig. 11.10 Log-log plot of the cross sections for quenching of Rb (x) and Na (O) levels having approximately n 13 by He against the energy defect AW between the level of interest and its closest state (from ref. 32).

Inert gases have very small cross-sections for quenching Na(3 2P), whereas for all the polyatomic molecules which have been studied, the quenching cross-sections are of the same order of magnitude as gas kinetic cross-sections. It is suggested later that this is not because a polyatomic molecule can accept most of the energy internally. Table 14 lists quenching cross-sections for a number of diatomic mol-... 

Cross sections for quenching NOj fluorescence by different gases (excitation wavelength = 435.8 nm)... 

He -Oj character. There is conflicting evidence regarding this hypothesis Leu and Siska found support for an attractive He -02 interaction from the bioad angular distribution of the O Penning ions however, the cross-section for quenching of He(2 5) by Oi has a positive temperature dependence at thermal energies, which favours a repulsive interaction. 

FIGURE 3.2 Cross -sections for quenching of the u = 1, y = 0 level of D2 in collisions with Ar atoms resolved into the different rotational levels/ in v = 0 as functions of the incident kinetic energy. (From Uudus, N. et al., J. Chetn. Phys., 122,024304, 2005. With permission.)... 

Hydrocarbons. Recent measurements of c- a LIF [21] and c a emission [2, 27] following HN3 laser photolysis gave the following rate constants and cross sections for quenching by some simple hydrocarbons the last column gives the cross sections recommended on the basis of these results ... 

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