  Using event-by-event fluctuations, we study the diffusion parameters of
net-charge, net-pion, net-kaon, and net-proton in the heavy-ion jet interaction
generator (HIJING), and ultra-relativistic quantum molecular dynamics (UrQMD)
models at different collision energies \sqsn available at BNL Relativistic
Heavy Ion Collider (RHIC). The diffusion parameter ($\sigma$) of net-charge and
identified particles are estimated in rapidity space at various \sqsn. It is
observed that, the $\sigma$ values are independent of collision energies but
emphasises the particle-species dependence of diffusion coefficient in the QGP
medium. The present work on particle-species dependence of diffusion
coefficient provides a baseline for comparison with the experimental data.
