Fig. 2. NIR part of the absorption spectra (bold lines) of the ‘black’ porphyrins 3-M and ICG at λ _max with O.D. = 1 (in DMF in a 1 cm cuvette, conc. (in μM) of ICG = 10.6, 3-2H = 30.6, 3-Zn = 20.3, 3-Cu = 23.3 and 3-Co = 36) and tube phantom PA spectra (dotted lines) of respective solutions.