For this purpose, all investigated systems show unsatisfactory high Ith, with values above 200 mW cm -2 (Figure ,D and Figure ). This emanates from the fact that tT is quite short in these annihilators, combined with a relatively low molar absorptivity of 4CzBN at the excitation wavelength 405 nm (e » 7000 M -1 cm -1 ). Comparison between Ith obtained by evaluation at b = 0.5 (Figure ) and the traditional evaluation of Ith obtained from fitting the steady-state intensity to slopes 1 and 2 (Figure ) yield good agreement between the methods.