As shown in Figure , ample experimental investigations have been carried out to study the rate coefficients (denoted as k, in cm 3 molecule -1 s -1 ), branching ratios between R1 and R2, as well as kinetic isotope effect. Most experimental measurements focused on kinetics over the temperature between 200 and 2000 K. The measured branching ratios of the R2 channel (defined as k2 / kt, kt = k1 + k2) were 0.11±0.03, 18 0.17±0.13, 19 0.25±0.08, 20 0.17±0.03, 23 0.15±0.08 at 298 K, 0.22±0.07 at 393 K, and >80% at 900 ~ 1300 K. Recently, the title reaction was found to play an important role in the interstellar medium.