The light flux (3 108 mol s1) emitted by
the UV LED400 (lmax ¼ 400 nm) was determined by ferrioxalate
actinometry [29]. The concentration of photogenerated paramagnetic
species was evaluated from the double-integrated EPR
spectra based on the calibration curve obtained from the EPR
spectra of Tempol or Tempone solutions measured under strictly
identical experimental conditions. The experimental EPR spectra
were analyzed and simulated using the Bruker software (WinEPR),
and Winsim2002 software [30].