Goppert-Mayer, Maria

All the previous discussion in this chapter has been concerned with absorption or emission of a single photon. However, it is possible for an atom or molecule to absorb two or more photons simultaneously from a light beam to produce an excited state whose energy is the sum of the energies of the photons absorbed. This can happen even when there is no intemrediate stationary state of the system at the energy of one of the photons. The possibility was first demonstrated theoretically by Maria Goppert-Mayer in 1931 [29], but experimental observations had to await the development of the laser. Multiphoton spectroscopy is now a iisefiil technique [30, 31]. 

In the 1930s, Maria Goppert-Mayer [12], theoretically predicted the process of an atom being raised to an excited state of energy equal to the sum of two simultaneously... 

Maria Goppert-Mayer (1906-1972). Johannes Hans Daniel Jensen (1907-1973). 23John Dalton (1766-1844). 

Two-photon excitation was predicted by Maria Goppert-Mayer in 1931 [189] and introduced into laser microscopy by W. Denk, J.H. Strickler, and W.W.W. Webb in 1990 [132]. The wavelength of two-photon excitation is twice the absorption wavelength of the molecules to be excited. Because two photons of the excitation... 

Two-photon excitation was predicted in her doctoral thesis by Maria Goppert-Mayer [88], who recognized that it was a corollary of the Kramers-Heisenberg-Dirac theory of light scattering. It was not observed experimentally until 30 years later, when pulsed ruby lasers finally provided the high photon flux that was required [89]. Goppert-Mayer received the physics Nobel prize in 1963 for imre-lated work on nuclear structure. 

In 1931 in her doctoral dissertation supervised by Max Bom, Maria Goppert-Mayer proposed the concept of the simultaneous absorption of two photons by a molecular system in one elementary action,(English translation Ref ). This prediction was based on the principles of the quantmn theory of radiation " as well as the concept of the intermediate energy level. Based on the formalism of summation over all eigenstates of the system, Maria Goppert-Mayer derived an expression for the two-photon absorption probability which, however, occurred to be too low to be experimentally observed in the incoherent light excitation regime. Hence, the unquestionable experimental confirmation took over thirty years. ... 

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