To prove the source of self-quenching in trans-Pt(P(C8H17)(3))(2)(C CC6H4C CC6H5)(2) is a result of triplet excimer formation, we carried out nanosecond transient absorption measurements on multiple concentrations. By examining the kinetics we were able to determine rate constants for the formation and decay of the triplet excimer, 4.7 x 10(6) M-1 s(-1) and 6.9 x 10(5) s-(1,) respectively. We determined the transient absorption spectrum for the excimer which has an extinction coefficient maximum per excimer unit of 95 680 M-1 cm(-1) at 600 nm. Experimental analysis suggests that the formation of the triplet excimer is largely due to ligand-ligand interactions. (c) 2007 Elsevier B.V. All rights reserved.