Magnetic quenching

There are a few important consequences of this interaction, besides the magnetic quenching. While free Ni clusters have virtually no gap at the Fermi level, a typical sign of developing metallic character, carbonylated Ni clusters do have a gap of ca 1-2 eV, typical of semiconducting materials (Fig. 11). 

From the magnetic quenching experiments by Degenkolb et al. and Chapman and Bunker, it is possible to estimate the potential energy curve... 

The pressure dependence of the fluorescence intensity vs. magnetic field strength curve indicates that the magnetic quenching is due to an increase in the collisional quenching cross section caused by the niagnetic field. 

Solarz et al. and Butler and Levy found that the magnetic quenching curves can be fitted to the Lorentzian function... 

To examine the dependence of the magnetic-quenching effect on the field strength, Kiittner et al. scanned the magnetic field and measured continuously fluorescence lifetimes while scanning the magnetic field at different... 

The striking difference in the magnetic quenching behavior of glyoxal compared to the other systems noted above can be seen in that this is a... 

In the following we discuss the general theories of intra- and intermolecular magnetic quenching separately. The theoretical results of intramolecular magnetic quenching will in particular apply to the magnetic predissociation of diatomic molecules (Sections IV and V). 

In a recent work, Atkins and Stannard (1977) have proposed two mechanisms to describe the magnetic quenching effect by an enhancement of radiationless decay. They describe the radiationless decay by the Bixon-Jortner model (Bixon and Jornter, 1968) ... 

As discussed in Section II, the Ij and CS2 molecules show intramolecular magnetic quenching while the radiationless process associated with the magnetic quenching of I2 involves the transition between the bound state and the dissociating state, the radiationless process associated with the magnetic quenching of CS2 involves the transition between the two bound states. 

Now we discuss magnetic quenching. In the presence of a magnetic field, both energies and wavefunctions will be perturbed. To consider this magnetic effect, let us use Eq. (88) as an illustration. This type of equation can be used... 

As in the case of intramolecular magnetic quenching, it can be shown that q( )L i = 0> and that k TY l consists of three terms each term can be treated in exactly the same way as in Section III,A. For example, the first term in Eq. (95) can be expressed as... 

In the above discussion, although we have attempted to outline a general approach for treating intermolecular magnetic quenching due to direct... 

It follows that the collision-induced magnetic-quenching rate constant kcc T,H) is given by (Selzle et al., 1979)... 

According to the collision complex model, the saturation effect is observed when the magnetic field is high enough so that W E, H) K(E). Notice that the systems like NO2 and glyoxal, which exhibit intermolecular magnetic quenching, show a saturation effect. 

Next we briefly discuss how other models of collision-induced ISC can be applied to intermolecular magnetic quenching. According to Selwyn and Steinfeld (1969) and Thayer and Yardley (1972,1974), the transition rate due to collisional quenching can be calculated by using the Fermi golden rule. 

In Section III we presented a general treatment of intramolecular magnetic quenching in this section we apply the theory to the magnetic predissociation of diatomic molecules. For purposes of comparison, the spontaneous predissociation of diatomic molecules is also discussed in this section. Notice that in this case the final state is in the dissociating (or repulsive) state. 

Conventionally, for magnetic quenching a simplified version of the following expression is used (Degenkolb et al., 1969 Chapman and Bunker, 1972) ... 

We have shown that in general the expression for the magnetic-quenching constant consists of seven terms, and Eq. (150) represents only one of them. In other words, the conventional treatment of magnetic quenching may have underestimated the magnetic-quenching effect. 

Magnetic quenching has only begun to attract attention, and most calculations so far are limited to the 12 case. In this section, we discuss the calculation of the magnetic predissociation of the state of I2. 

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