Emission spectra of multicharged xenon ions produced by a laser gas puff ar
e observed with high spectral resolution in the 8.5-9.5 and 17-19 Angstrom
wavelength ranges. Three different theoretical methods are employed to obta
in 3l-n'l' (n' = 4 to 10) wavelengths and Einstein coefficients for Ni-like
Xe26+. For the 3d-4p transitions, very good agreement is found between the
experimental wavelengths and the various theoretical wavelengths. These ac
curate energy level measurements can be useful for studying the Ni-like xen
on x-ray laser scheme. On the other hand, several intense spectral lines co
uld not be identified as 3l-n'l' lines of Ni-like xenon, despite the very g
ood agreement between the wavelengths and Einstein coefficients calculated
for these transitions using the three different methods.