Atomic data and spectral line intensities for Ni XVI

Electron impact collision strengths and spontaneous radiative decay rates a re calculated for Ni XVI. The data pertain to the 40 levels of the configur ations 3s(2)3p, 3s3p(2), 3s(2)3d, 3p(3), and 3s3p3d. Collision strengths ar e calculated at five incident electron energies: 10.0, 20.0, 30.0, 30.0, an d 50.0 Ry. Relative spectral line intensities are calculated for all astrop hysically important transitions. These are obtained by computing the excita tion rate coefficients (cm(3) s(-1)), that is, the collision strengths inte grated over a Maxwellian electron distribution, and then solving the equati ons of detailed balance for the populations of the 40 energy levels, assumi ng a collisional excitation model and an electron temperature of 2.51 x 10( 6) K. This temperature is typical for Ni XVI when formed in equilibrium by collisional ionization and recombination. With the excitation rate coeffici ents and the radiative decay rates, level populations are computed for seve ral electron densities and are given in this paper. We also investigate the effects of proton excitation and solar radiative excitation on the level p opulations and line intensities.