Hot reactions of 13N in solid methane at 77 K

The chemical reactions of recoil-13N were studied in solid methane at 77 K. 13N was generated via the the nuclear reaction 12C(d,n)13N. The radiation dose deliverd by the 8.5 MeV deuterons amounted to D* = 0.6 eV per target molecule. The products formed by high energy chemical processes (hot chemistry) were analyzed by radio-gaschromatography. 13NH3 with 52% and CH313NH2 with 25% radiochemical yield were found to be the main products. HC13N was not formed, but CH313CN amounts to 4%. For the more complex products carbon chain prolongation is prefered over multiple methylation such as show the yields of 8% for C2H513NH2 and 3% (CH3)213NH. (CH3)3N was not detected. The formation of 13NH3 is due to hydrogen abstraction, that of CH313NH2 due to insertion of NH radical into the C-H bond of CH4. Another, however, less probable pathway could be the insertion of 13N into methane. The methylamine radical may react with another methane molecule via hydrogen transfer to methylamine or attack to CH4 to dimethylamine. The 13N-products were formed with high radiochemical purity and can potentially be applied for the synthesis of 13N-radiopharmaceuticals. The reactions studied bear also informations on chemical processes in space (e.g. solar wind interactions with comets or interplanetary dust). 13N-high energy chemical products are, however, of a less exobiological significance then those formed by hot carbon atoms, e.g. in the 'mirror' system 11C/NH3(s). (orig.)