"Einstein Transition Probability"@en . . "\\(\\frac{-dN_j}{dt} = A_jkN_j\\), where \\(-dN_j\\) is the number of molecules spontaneously leaving the state j for the state k during a time interval of duration \\(dt\\), \\(N_j\\) is the number of molecules in the state j, and \\(E_j > E_k\\)."^^ . . "A_jkN_j" . . . "http://electron6.phys.utk.edu/qm2/modules/m10/einstein.htm"^^ . . "Given two atomic states of energy \\(E_j\\) and \\(E_k\\). Let \\(E_j > E_k\\). Assume the atom is bathed in radiation of energy density \\(u(w)\\). Transitions between these states can take place in three different ways. Spontaneous, induced/stimulated emission, and induced absorption. \\(A_jk\\) represents the Einstein transition probability for spontaneous emission."^^ .