... â 20 04 Marcel Dekker, Inc Interaction of Electrons and Photons 2. 3.3 33 Spontaneous Emission and Stimulated Emission of Photons From Eqs (2. 50b), (2. 57b), (2. 58) and (2. 59), the probability of ... assumption by Planck and statistical mechanics, he deduced relations between the coefficients A21, B 12, and B21: !3 B21 p2 c3 ẳ B21 A21 ẳ 2: 68aị B 12 2:68bị B 12, B21, and A21 are the absorption, ... made of Eqs (2. 34), (2. 36b), and (2. 39) Application of hCJ j to both sides of Eq (2. 41), with the use of the orthonormal relation Copyright â 20 04 Marcel Dekker, Inc Interaction of Electrons and...