If the H-transfer possibility is confirmed by the analysis of the PES, it is also interesting to point out that the transfer itself does not seem to alter a favourable energetic order of states potentially leading to ISC crossing. Indeed, S1 PES is crossing twice a triplet state along the transfer coordinate and the general quasi-degeneracy with the triplet manifold is maintained. Hence, while H-transfer should be considered as a clearly competitive process in the relaxation and de-excitation of enol CURC its final and global effect on the ISC rate and quantum yield appears less evident and necessitates a dynamic treatment to be properly taken into account.