Charge transfer reactions producing luminescence

Reported data for atomic charge-transfer reactions that produce luminescence are summarized in Table IV.A. Many of the initial studies were concerned with reactions of He+ with rare-gas atoms. These were also the first processes yielding luminescence to be studied over a wide translational-energy range. Very large cross sections for radiative emissions were observed from reactions such as... 

This reaction as written is energy-deficient, i.e. the first excited singlet state of Ru(II) is inaccessible directly. The emission of the Ru(II) species, produced in this electron-transfer reaction, was therefore ascribed to a charge transfer, spin-forbidden luminescence [41],... 

From a practical standpoint, much of the interest in the role of excited states in ionic interactions stems from their importance in ionospheric chemistry.Ih In addition, it has been realized more recently that certain ion-neutral interactions offer a comparatively easy means of populating electronically excited reaction products, which can produce chemiluminescence in the visible or UV region of the spectrum. Such systems are potential candidates for practical laser devices. Several charge-transfer processes have already been utilized in such devices, notably He+(I,He)I + and He2+(N2,2He)N2+.3 Interest in this field has stimulated new emphasis on fundamental studies of luminescence from ion-neutral interactions. 

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