The 9H tautomer may also undergo a direct and entirely barrierless radiationless photodeactivation leading directly from the Franck-Condon region to a peaked S 1 (ππ*)/S 0 conical intersection (see Fig. ). This process is driven by the aromatic purine ring puckering at the C 6 carbon atom alongside substantial twisting of the C 6 -NH 2 amino group and is a more direct way of accessing this conical intersection. Since such barrierless excited-state ring-puckering processes were shown to occur in nucleobases on a sub-picosecond timescale, this mechanism is most likely much faster than the resolution of our probe pulse and we would not be able to record it with our experimental setup. Nevertheless, we expect this mechanism to be an important contributor to the overall photorelaxation of 9H 2,6-dAP, even when excited near its absorption origin.