Figure 1 Characterizations
of elemental sulfur powder. (a) UV–visible
absorption spectrum, with its photograph showing as inset; (b) XRD
pattern; (c) time-resolved emission scanning spectrum under the excitation
of 280 nm; (d) digital photos before and after switching off 254 nm
UV light at 77 K; (e) temperature-dependent phosphorescence spectra,
(f) emission lifetime, and (g) phosphorescence excitation spectra;
(h) calculated (left) electronic band structures and (right) densities
of states (DOS); (i) EPR spectrum; (j) evolution of current density
as a function of irradiation time with a xenon lamp.