Deconstructing organometallic LEDs

A while back I posted Key questions about organometallic LED materials.  Two of the questions were:

2. What is the non-radiative path from the emitting state? [i.e. what is the relevant vibrational co-ordinate?]

5.  Is there a metal-centred (MC) excited state that is relevant to non-radiative decay?

[See also a Feature Article, Anthony Jacko, Ben Powell, and I wrote recently].
I just found a nice JACS paper, which comprises a combined theoretical and experimental study to help answer these questions. The abstract states:

The kinetic parameters for decay and results from density functional theory (DFT) calculations of the triplet state are consistent with a nonradiative process involving Ir−N (Ir−C for fac-Ir(pmb)₃) bond rupture leading to a five-coordinate species that has triplet metal-centered (³MC) character. Linear correlations are observed between the activation energy and the energy difference calculated for the emissive and ³MC states. 

The paper has several helpful figures such as the one below.