High temporal resolution observations of the pulsar microstructure at 102 MHz

We report observations of the microstructure of 7 pulsars at 102 MHz with a time resolution of up to 1 mus. We have detected fine pulse structure with a mus time-scale for all seven pulsars. We observe that interstellar scattering does not broaden the mus time-scale pulsar microstructure, and find structure of a time-scale much shorter than the interstellar scatter broadening. In addition to the previously known structure with time-scale tau(mu) of tens of mus, we have detected structures with characteristic time-scale of a few mus, nearly equal to the reciprocal of the analysis bandwidth. This suggests that even shorter micropulses may exist. Micropulses usually cluster in groups, each of duration tens to hundreds of mus, which may be identified as microstructure observed previously with smaller time resolution. In addition to the previously known quasi-periodicity of hundreds of milliseconds, we reveal a structures with characteristic period of tens of mus. We observe structures with short quasiperiodicity to have a limited bandwidth. The characteristic period P-mu of these structures in PSR B0950 + 08 does not have a common value for different frequency regions in the same single pulse. Scattering was revealed as a train of quasi-periodic micropulses with an exponentially damped envelope. The scatter-broadening and decorrelation bandwidth were measured. We report two time-scales of decorrelation bandwidth of pulsar PSR B0950 + 08 and propose two branches of Deltanu(d)(nu) dependence. The dispersion measure of PSR B0950 + 08 as DM = 2.9686 +/- 0.0001 pc cm(-3) has been determined.