000004755 001__ 4755 000004755 005__ 20200203154343.0 000004755 0247_ $$2DOI$$a10.1093/mnras/stz857 000004755 037__ $$aSCART-2020-0055 000004755 100__ $$aGuzmán, F. 000004755 245__ $$aH-, He-like recombination spectra - III. n-changing collisions in highly excited Rydberg states and their impact on the radio, IR, and optical recombination lines 000004755 260__ $$c2019 000004755 520__ $$aAt intermediate to high densities, electron (de-)excitation collisions are the dominant process for populating or depopulating high Rydberg states. In particular, the accurate knowledge of the energy changing (n-changing) collisional rates is determinant for predicting the radio recombination spectra of gaseous nebula. The different data sets present in the literature come either from impact parameter calculations or semi-empirical fits and the rate coefficients agree within a factor of 2. We show in this paper that these uncertainties cause errors lower than 5 per cent in the emission of radio recombination lines of most ionized plasmas of typical nebulae. However, in special circumstances where the transitions between Rydberg levels are amplified by maser effects, the errors can increase up to 20 per cent. We present simulations of the optical depth and Hnα line emission of active galactic nuclei broad-line regions and the Orion Nebula Blister to showcase our findings. 000004755 594__ $$aNO 000004755 6531_ $$aatomic data 000004755 6531_ $$aatomic processes 000004755 6531_ $$amasers 000004755 6531_ $$aH II regions 000004755 6531_ $$aradio lines: general 000004755 6531_ $$asubmillimetre: general 000004755 6531_ $$aAstrophysics - Astrophysics of Galaxies 000004755 6531_ $$aPhysics - Atomic Physics 000004755 700__ $$aChatzikos, M. 000004755 700__ $$avan Hoof, P. A. M. 000004755 700__ $$aBalser, Dana S. 000004755 700__ $$aDehghanian, M. 000004755 700__ $$aBadnell, N. R. 000004755 700__ $$aFerland, G. J. 000004755 773__ $$c1003-1018$$n1$$pMonthly Notices of the Royal Astronomical Society$$v486$$y2019 000004755 8560_ $$fpeter.vanhoof@observatoire.be 000004755 85642 $$ahttps://arxiv.org/abs/1903.05730 000004755 905__ $$apublished in 000004755 980__ $$aREFERD