Intensity of lines from low-lying levels in C ii, N iii, O iv, Ne vi, Mg viii, Si x, and Si ii

The intensities of the lines for the transition ²P₃^2/0-²P₁^2/0in C II, N III, O IV, Ne VI, Mg VIII, Si X, and Si II in the chromosphere-corona transition region are investigated. The populations of the excited state ²P_f3/2^p0 relative to the ground state ²P_f1/2⁰ are obtained by considering all the radiative and collisional transition processes including the collisional transitions to the higher states which cascade to the upper level. It is found that in the transition region the intensity (which may be expressed as a function of temperature only) increases with the charge on the ion for a sequence.