Spectroscopy of Spin-Flip Transitions

Collision-induced transitions between fine-structure components where the relative orientation of the electron spin with respect to the orbital angular momentum is 

Collision-induced spin-flip transitions in molecules transfer the optically excited molecule from a singlet into a triplet state, which may drastically change its chemical reactivity [1028]. Such processes are important in dye lasers and have therefore been intensively studied [1029]. Because of the long lifetime of the lowest triplet state To, its population N(t) can be determined by time-resolved measurements of the absorption of a dye laser tuned to the transition T.  

A laser-spectroscopic technique for investigations of spin-flip transitions under electron impact excitation of Na atoms [1030] is shown in Fig. 8.13. Opti- 

Collision-induced transitions between fine-structure components where the relative orientation of the electron spin with respect to the orbital angular momentum is changed have been studied in detail by laser-spectroscopic techniques [13.60]. One of the methods often used is the sensitized fluorescence, where one of the fine structure components is selectively excited and the fluorescence of the other component is observed as a function of pressure [13.61]. Either pulsed excitation and time-resolved detection has been used [13.62] or the intensity ratio of the two fine-structure components is measured under CW excitation [13.63]. 

At the end of this section Fig.13.14 summarizes all possible collision-induced transitions from a selectively excited molecular level vi[,Jk) to other molecular or atomic levels. 

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