Abstract
Using laser excitation of the 62P levels in the natural isotopic mixture of Rb atoms, modulation of superradiance intensity from some transitions to the lower levels was observed. On the transition 62P1/2-62S1/2 this effect is interpreted as a quantum beat between the hyperfine-structure transitions of the Rb85 and Rb87 isotopes. A nearly 'single-pulse' superradiant signal was obtained on the 62P-42D transitions. When a magnetic field was applied transverse to the direction of the laser beam, the pulses obtained showed the properties forecast by two-level superradiance theory. Preliminary results are reported.