Laser emission from binary solutions of organic compounds

An investigation was made of the coherent emission from binary solutions of organic compounds pumped by the fourth harmonic of a neodymium laser. Binary solutions of two types were studied: In those of the first type both components readily emitted coherent radiation; those of the second type contained a donor in the form of a nonlasing organic compound with a low quantum efficiency of the fluorescence. A comparison of the experimental and calculated dependences of the laser threshold and emission frequency on the partial concentrations of the donor and acceptor yielded the rate constants of the singlet–singlet transfer of the excitation energy.