Radio pulsar microstructure at 1 . 41 and 4 . 85 GHz

We report on observations of microstructure at 4.85 and 1.41 GHz of pulsars strong enough for the observation of single pulses with time resolution between 7 µs and 160 µs. All five pulsars observed at 4.85 GHz show microstructure in a large fraction of their pulses. We confirm that microstructure seems to be a common property of the pulsar emission mechanism and not only an additional feature of some pulsars. We show that, for those pulsars observed earlier at lower frequencies, there is little variation in microstructure parameters at different frequencies. The fraction of pulses showing microstructure tends to be higher at 4.85 GHz when compared with lower frequency observations. We argue that the short timescale of microstructure reflects the extension of the emitting structures.