Fig. 1: Mechanically induced surface-bound radicals and structural amorphization of quartz.
From: An abiotic source of Archean hydrogen peroxide and oxygen that pre-dates oxygenic photosynthesis
a EPR spectra of quartz before and after being ground in N2 for 1 and 5 h. Three types of surface-bound radicals were identified, i.e., peroxy radical (≡SiOO•, gzz = 2.064; gyy = 2.007; gxx = 2.002), surface-bound superoxide ion (≡Si+O2•−, gzz = 2.044; gyy = 2.010; gxx = 2.002), and E′ center (≡Si•, g// = 2.001; g┴ = 2.000). b XRD patterns of quartz washed by 10 wt.% hydrofluoric acid (QW) and quartz ground in N2 atmosphere for 1 h (QGN-1h) and 5 h (QGN-5h).
