Multiple quantum frequency conversion

A molecular system having two energy levels separated by and coupled to an electromagnetic field by a transition dipole moment will resonantly absorb energy at all odd sub-harmonics of the energy level separation .... These correspond to 1, 3, 5,... quantum absorption processes. Part of this absorbed energy is emitted back into the field at harmonics of and part is dissipated into the lattice degrees of freedom. It is therefore possible to drive the molecular system with a field of frequency (n odd), and obtain radiation at a frequency . Here we present results of a theoretical study of these resonant multi-quantum conversion processes. Two characteristic regions of operation are predicted: one previously discussed by Fontana, Pantell and Smith³in which the molecular efficiency = (power converted to )/ (power abosrbed at ) = under conditions of maximum power converted per unit volume; and another region (not previously reported) in which maximum power conversion per unit volume can occur with molecular efficiencies approaching unity.