Figure 2

EPR spectrum of the gallate free radical in D ₂ O. The solution contains 1 mM gallic acid in 100 mM potassium phosphate with the pD adjusted by addition of NaOH. Top: This spectrum is consistent with hyperfine splittings due to only two protons (a^H = 1.04 G and a^H = 0.21 G). (The apparent intensity of this spectrum should not be compared directly to the parallel spectrum in Figure 1 as the experiments were not designed for such comparisons to be made.) Bottom: EPR spectrum of the gallate free radical at pD 11. This 1:2:1 spectrum is described by two identical hyperfine splitting constants a^H = 1.07 G (2), identical to the spectrum observed in H₂O at pH 11.