Ladder excited states

The two iron ions of the Rieske cluster are antiferromagnetically coupled therefore, the ground state has a spin S = while excited states of the spin ladder S = I, i, I, and, are at energies -3J, 8J,... 

In Figs. 42b, c the ionic excited states have the full molecular symmetry and by including diagonal hole-hole and hole-electron ladders in analogy with Figs. 42d,e will... 

There are several other interesting topics in quantum optics which we would like to be able to study. For example, we would like model problems in double resonance spectroscopy, where there are two electromagnetic fields with possibly different polarizations simultaneously interacting with a molecule. This problem resembles the multiple photon excitation problem in that there is population migration along ladders of states, but in this case there can be a vastly larger number of quantum levels to treat — on the order of 2(2J+1). At room temperature, the most probable value of J for SF is about 60, which implies a 250 state calculation. 

Our experiments use a weak probe field P to excite molecular levels (possibly degenerate) that are coupled by a stronger field S to more highly excited states in a three-level ladder linkage of energies Eg < Ee < Ef. Fig. 1 shows the states involved, and the spontaneous emission which is detected, as discussed below. 

Regular ladders of doubly, triply, and quadruply excited states tending to fragmentation thresholds where the electronic geometry is symmetric... 

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