  We investigate the effect of temperature on the electronic and crystal
structures of Ca1-xSrxRuO3 via the evolution of O 1s core level spectra as a
function of temperature and composition, x. O 1s spectra in SrRuO3 exhibit a
dominant sharp feature at all the temperatures with a small trace of impurity
feature at higher binding energies. The spectra in Ca doped samples, however,
exhibit two distinct features. Analysis of the experimental spectral functions
and the band structure results suggest that different Madelung potential at the
two types of oxygen sites in the orthorhombically distorted structure leads to
such splitting in the O 1s spectra. Interestingly, the energy separation of
these two features becomes smaller at low temperatures in the Ca dominated
samples concomitant to the observation of non-Fermi liquid behavior in their
bulk properties. Such temperature evolution, thus, indicates a direct
connection of the lattice degrees of freedom with the electronic properties of
these compounds.
