Fig. 2. UV/Vis/NIR absorption spectra of (a) 1 ³⁽˙⁺⁾ and (c) 2 ³⁽˙⁺⁾ recorded over a range of different concentrations. Dependence of the intensity of the band at (b) at 900 nm for 1 ³⁽˙⁺⁾ and (d) 1083 nm for 2 ³⁽˙⁺⁾ on concentration. In both cases, the linear relationships point to the fact that absorption bands result from intramolecular radical-pairing interactions.