Fig. 1: Possible mechanism for the photolysis of alkyl diazirine.

(a–d) Four possible models on the basis of previous findings, inter-conversion pathways, and kinetic mechanisms. Diazo B and carbene C are the two intermediates that can be generated from the alkyl diazirene A upon irradiation, which eventually yields D. (e-h) Time-dependent concentration changes of A, B, and D are plotted for these four models. Here, \({\left[{{{{\rm{A}}}}}\right]}_{t}={\left[A\right]}_{0}\exp \left(-\left({k}_{1}+{k}_{3}\right)\left[{hv}\right]t\right)\), \({\left[B\right]}_{t}=\frac{{k}_{1}{\left[A\right]}_{0}}{{k}_{1}-{k}_{2}{\prime}+{k}_{3}}\left(\exp \left(-{k}_{2}{\prime} \left[hv\right]t\right)-\exp \left(-\left({k}_{1}+{k}_{3}\right)\left[hv\right]t\right)\right)\), \({\left[D\right]}_{t}=\frac{{k}_{{ox}}}{{k}_{{ox}}+{k}_{{others}}}{\left[A\right]}_{0}\left(1-\frac{{k}_{1}}{{k}_{1}-{k}_{2}{\prime}+{k}_{3}}\exp \left(-{k}_{2}{\prime} \left[h\nu \right]t\right)+\frac{{k}_{2}{\prime} -{k}_{3}}{{k}_{1}-{k}_{2}{\prime}+{k}_{3}}\exp \left(-\left({k}_{1}+{k}_{3}\right)\left[h\nu \right]t\right)\right)\). In model I, \({k}_{3}=0\);\({k}_{2}{\prime}={k}_{2}\) except for model III where \({k}_{2}{\prime}={k}_{2}/[{hv}]\); in model IV, \({k}_{2}=0\). Detailed deduction of the equations can be found in Supplementary Note.