Types of Transitions between States

Following this model description of the absorption process, the rate at which stimulated absorption transitions are induced is given by 

it is possible to calculate the number of absorption transitions per time interval as follows  

The rate at which stimulated emission transitions from state j to state i are induced is given by 

The Physical Chemistry of Materials Energy and Environmental Applications 

Thereafter, the ratio between the probabilities for spontaneous and stimulated emission coefficients, Aj/B, is proportional to v3 the relative possibility of spontaneous emission augments with the energy of the emitted photon. 

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