RADIO PULSAR MICROSTRUCTURE AT 1.41 AND 4.85 GHZ

We report on observations of microstructure at 4.85 and 1.41 GHz of pu lsars strong enough for the observation of single pulses with time res olution between 7 mu s and 160 mu s. All five pulsars observed at 4.85 GHz show microstructure in a large fraction of their pulses. We confi rm that microstructure seems to be a common property of the pulsar emi ssion mechanism and not only an additional feature of some pulsars. We show that, for those pulsars observed earlier at lower frequencies, t here is little variation in microstructure parameters at different fre quencies. The fraction of pulses showing microstructure tends to be hi gher at 4.85 GHz when compared with lower frequency observations. We a rgue that the short time-scale of microstructure reflects the extensio n of the emitting structures.