  Fine-structure transitions can be involved in various processes including
photon absorption, charge transfer and inelastic collision between ions,
electrons and neutral atoms. We present fine-structure excitation and
relaxation cross sections for the collisions of the first few members of the
carbon isoelectronic sequence (C, N$^+$ and O$^{2+}$) with atomic hydrogen
calculated using quantum-mechanical methods. For C, the scattering theory and
computational approach is verified by comparison with previous calculations.
The rate coefficients for the collisional processes are obtained. For N$^+$ and
O$^{2+}$, the transitions correspond to the lines [\ion{O}{iii}] 52~{\textmu}m,
[\ion{O}{iii}] 88~{\textmu}m, [\ion{N}{ii}] 122~{\textmu}m, and [\ion{N}{ii}]
205~{\textmu}m, observed in the far-infrared in the local Universe and more
recently in high-redshift galaxies using radio interferometry. The influence of
different potentials on the cross sections and rate coefficients are
demonstrated.
