Thesis High-Resolution Photoemission Study of Kondo Insulators ...

6.3. Results and Discussion 85
distribution function. Thus we again divided the spectra by the FD function (convoluted
with a Gaussian corresponding to the energy resolution) as shown in the lower
panel of the figure. The spectral DOS thus obtained is found to increase with increasing
temperature in a rather wide energy region between EF and ∼−100 meV.
Intensity
DOS
LuB 12
hν = 21.2 eV
300 K
225 K
150 K
75 K
7 K
300 K
225 K
150 K
75 K
7 K
LuB 12
-150 -100 -50 0 50 100
Energy relative to E F (meV)
Figure 6.6: Temperature-dependent He I photoemission spectra of LuB12 (upper panel)
and those divided by the FD function convoluted with the instrumental resolution
(lower panel).
We note again that the intensity at EF in the spectra divided by the convoluted
FD function does not depend on uncertainties in the temperature nor the Gaussian
width, because the FD function is 0.5 at EF at any temperature even if that FD
function is convoluted with any Gaussian. However, an error in the temperature or the
Gaussian width might cause a spurious temperature dependence near EF in the FDfunction-divided
spectra. The fact that temperature dependence is more remarkable