Spin Orbit Relaxation

This lineshape analysis also implies tliat electron-transfer rates should be vibrational-state dependent, which has been observed experimentally [44]- Spin-orbit relaxation has also been identified as an important factor in controlling tire identity of botli electron and vibrational-state distributions in radiationless ET reactions. 

Before discussing individual results for spin orbit relaxation, a general framework for the kinetic treatment will be given. The rate of relaxation in a system involving only two states,... 

The efficiencies for spin orbit relaxation of electronically excited halogen atoms for all collisional partners investigated to date are given in Table IX. 

Fig. 12. Correlation of the rate constant (fc) for the spin orbit relaxation of l(5QPy2) with the excitation energy [ (j3)] of the colliding olefin. (1) Tetramethylethylene. (2) cis-and t/ww-2-Butene. (3) Isobutene. (4) 1-Butene. (5) Propylene. (6) Ethylene. ( 3) = E (units of a resonance integral 3 for a standard C=C bond).133...

To observe the kinetic effect of the chemical reaction of an electronically excited atom, the rate must be significantly different from that of the ground state atom, as spin orbit relaxation may compete with reaction. The separation of these processes is inherent in studies of the reactions of excited halogen atoms. Clearly, where a strong attractive potential facilitates chemical reaction, this chemical interaction will also aid spin orbit relaxation itself (Section VII). Thus relatively strongly endothermic, slow, chemical reaction... 

Iodine atom abstraction from an alkyl iodide by I 2/ ) is an exothermic process and thus may compete with spin orbit relaxation ... 

Nitrous Oxide, Ozone, and Nitrogen Dioxide.28 I(52Py2) undergoes slow, spin orbit relaxation in the presence of nitrous oxide (Table IX) rather than chemical reaction according to... 

Olefins.28 Spin orbit relaxation dominates the decay of I(52/ y2) in the presence of olefins,28 the data for which is given in Table IX. Since measurements on these systems are usually carried out in times short compared with those required for significant contributions from slow, termolecular atomic recombination, the evidence for the decay by a physical process can be seen from the reasonable balance maintained for [I(52Py2)] + [I(52/fya)]28 over the main part of the decay. There is no evidence for any significant role by the reaction... 

It should also be emphasized that in certain molecules the electrophilic character of the energy-transfer process may be sharply changed by resonance of the triplet mercury with a close-lying electronic level (NO) or by spin-orbit relaxation due to the presence of a suitable vibrational level in the substrate molecule (N2, CO, and partly H20, NH3, etc.). 

In other processes, the energy is converted from one form into another, for example the spin-orbit relaxation of Hg(63P1) by N29... 

A classical molecular system, which until recently was supposed to show systematic dependence on the change in internal energy, is the collisional spin-orbit relaxation of Hg(63P)... 

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