Mechanisms for the formetion of HCN and HNC on the intersteellar dust grains

对星际尘埃颗粒上发生的固相反应进行了实验模拟。低温冷却器和四极质谱仪被安置在真空室中。用FT-IR光谱仪测量了H原子与沉积在硅衬底上的样品反应生成的产物的红外光谱。采用具有两个光阱的瓶颈放电管，通过直流辉光放电产生氢原子。H_2等离子体的紫外光被涂在光阱上的石墨完全吸收。当光阱中含有接地的Mo丝时，从放电管中流出的电子被完全湮灭，N_2/CO混合气体放电形成的CN自由基沉积在硅衬底上并与H原子反应。用红外光谱（FT-IR）对HNC/HCN产物进行了表征，（CN）_2在紫外光照射下也生成了ON自由基。还研究了C_2烃与H、D原子的反应，发现在低温下，乙炔对H原子的反应活性远低于乙烯。

Experimental simulation was made for the elucidation of solid-phase reactions taking place on the interstellar dust grains. The cryocooler and a quadrupole mass spectrometer were housed in a vacuum chamber. Infrared spectra of products formed by the reaction of H atoms with deposited samples on the silicon substrate were measured using a FT-IR spectrometer. The hydrogen atoms were produced by the dc glow discharge using the bottle-neck discharge tube having two optical traps. The UV light from the H_2 plasma was completely absorbed by the graphite coated on the optical traps. When the grounded Mo wire included in the optical trap wasused, electrons effusing from the discharge tube were completely annihilated, The CN radicals formed by the discharge of N_2/CO mixed gas were deposited on the silicon substrate and reacted with H atoms. The HNC/HCN products were measured by means of FT-IR.In addition, ON radicals were also formed by the UV irradiation of (CN)_2. The reaction of C_2 hydrocarbons with H and D atoms were also investigated, It was found that acetylene was much less reactive than ethylene toward H atoms at cryogenic temperature.