  The directional spiking infrared and ultraviolet emission from sodium vapors
excited to the 4D5/2 level by a continuous-wave resonant laser pump, that
constitute a novel feature of the cooperative effects, has been analyzed.
Cascade mirrorless lasing at 2207 and 2338 nm on population-inverted
transitions and ultraviolet radiation at 330 nm that is generated due to
four-wave mixing process demonstrate a high degree of intensity correlation.
