X‐ray emission spectra of three different titanium‐containing thin films, Ti, TiO2, and TiN, were measured using 5.1 MeV 7Li2+, 4.4–6.8 MeV 12C3+, 6.8 MeV 16O3+, and 11.9 MeV 63Cu6+ beams as excitation. The energy spectra were collected using a high energy resolution transition‐edge sensor array. In all measurements, the average L‐shell vacancy fraction was higher for the metallic Ti than for the other samples, whereas the difference between TiN and TiO2 was negligible. The universal variable Xn of the geometrical model was used to study the systematics of the average L‐shell vacancy fraction at the time of Kα emission. Our experiments expand previously studied Xn values, and a fairly good agreement with previous studies was found.