The following data set contains valid photoionization frequencies and electron impact ionization frequencies for the primary neutral species CO2, O, CO, N2, and Ar in the dayside ionosphere of Mars, calculated from MAVEN in situ data from November 1, 2014 until December 12, 2019.  It also contains necessary ancillary data, including Time UTC, Mars season, solar zenith angle, spacecraft altitude, atmospheric pressure, normalized on attenuated CO2 photoionization frequency (as a proxy for solar activity), the neutral densities of the primary neutral species, and the magnitude and elevation angle of a model magnetic field calculated by Morschhauser et al. [2014] (DOI: 10.1002/2013JE004555) and normalized to 400 km altitude.  It is the primary source for the figures contained in the manuscript 2021JE006923: "Ionization efficiency in the dayside ionosphere of Mars: structure and variability", by Robert J Lillis, Shaosui Xu, David Mitchell, Ed Thiemann, Frank Eparvier, Mehdi Benna, Meredith Elrod.

The methods for calculating both the photoionization frequencies and electron impact ionization frequencies are contained within manuscript 2021JE006923: , "Ionization efficiency in the dayside ionosphere of Mars: structure and variability", by Robert J Lillis, Shaosui Xu, David Mitchell, Ed Thiemann, Frank Eparvier, Mehdi Benna, Meredith Elrod.