For instance, the C1s for C2=C3 and C5=C6 of NBD are the smallest at 290.02 eV, while the C1s of C2=C3 of NBN is 290.12 eV. Hence, chemical reactions are likely to break the C=C double bonds of NBD (and NBN) due to the difficulty in ionizing C-C single bonded carbons in NBD .