Excitation temperature, T_ex, (in K) as a function of log(n_H2) (in cm⁻³) at two kinetic temperatures – 10 K (left panels) and 40 K (right panels) – of the gas. Solid lines correspond to the T_ex determined using the rate coefficients computed in this work, while dashed lines represent those from the LAMDA database. Red and blue lines indicate column densities of 10¹² and 10¹⁵ cm⁻², respectively.