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The energy of an electron is determined by its orbit around the atom, The n = 0 orbit, commonly referred to as the ground state, has the lowest energy of all states in the system. In atomic physics and chemistry , an atomic electron transition (also called an atomic transition, quantum jump, or quantum leap) is an electron changing from one ...
In quantum mechanics the basis for a spectroscopic selection rule is the value of the transition moment integral [1], =, where and are the wave functions of the two states, "state 1" and "state 2", involved in the transition, and μ is the transition moment operator.
For example, the absorption spectrum for ethane shows a σ → σ* transition at 135 nm and that of water a n → σ* transition at 167 nm with an extinction coefficient of 7,000. Benzene has three aromatic π → π* transitions; two E-bands at 180 and 200 nm and one B-band at 255 nm with extinction coefficients respectively 60,000, 8,000 and 215.
In quantum physics, Fermi's golden rule is a formula that describes the transition rate (the probability of a transition per unit time) from one energy eigenstate of a quantum system to a group of energy eigenstates in a continuum, as a result of a weak perturbation.
Classically, the Franck–Condon principle is the approximation that an electronic transition is most likely to occur without changes in the positions of the nuclei in the molecular entity and its environment. The resulting state is called a Franck–Condon state, and the transition involved, a vertical transition.
However, the electron as an elementary particle cannot be divided, it resides either on the donor or the acceptor and arranges the solvent molecules accordingly in an equilibrium. The "transition state", on the other hand, requires a solvent configuration which would result from the transfer of half an electron, which is impossible.
The hyperfine transition as depicted on the Pioneer plaque. As the hyperfine splitting is very small, the transition frequencies are usually not located in the optical, but are in the range of radio- or microwave (also called sub-millimeter) frequencies. Hyperfine structure gives the 21 cm line observed in H I regions in interstellar medium.
The observation of electron tracks that were independent of the frequency of the incident photon suggested a mechanism for electron ionization that was caused from an internal conversion of energy from a radiationless transition. Further investigation, and theoretical work using elementary quantum mechanics and transition rate/transition ...