2026ApJ...999...65R

We present a comprehensive single-pulse study of three pulsars, namely PSRs J1854-0036, J2159+0202, and J2112+0740, discovered by the Five-hundred-meter Aperture Spherical radio Telescope (FAST) in the Commensal Radio Astronomy FAST Survey (CRAFTS). We observe that these pulsars display different kinds of single-pulse phenomena, bearing implications for pulse emission mechanisms and geometry. PSR J1854-0036 exhibits quasiperiodic nulling with a nulling fraction of 31% ± 1% and a periodicity of (127.4 ± 0.4)P (where P is the spin period of the pulsar). We identified a weak emission in the null profile, suggesting either a global magnetospheric state switching or a change in geometric orientation rather than complete cessation of emission. PSR J2159+0202 exhibits complex subpulse drifting or intensity modulations with periodicities ranging from P₃ = (7.0 ± 0.2)P to (10.9 ± 0.1)P. PSR J2112+0740 exhibits burst-like radiation without evidence of nulling or coherent subpulse drifting, potentially associated with stochastic pair production or plasma instabilities within the pulsar's emission region. These results highlight the multiscale nature of the pulsar emission, potentially linking nulling, drifting, and erratic radiation to different magnetospheric processes.