50-keV/u Ne^(8+)离子碰撞导致的C_(3)H_(4)^(2+)三体解离机制

Three-body fragmentation dynamics of C_(3)H_(4) induced by 50-keV/u Ne^(8+) ion impact

利用反应显微成像谱仪开展了50-keV/u Ne^(8+)离子与C_(3)H_(4)分子碰撞实验,研究了丙二烯(CH_(2)CCH_(2))和丙炔(CH^(+)CCH)两种同分异构分子形成C_(3)H_(4)^(2+)二价离子并解离产生H^(+)C_(3)H_(4)H的过程.实验获得了H^(+)和C_(3)H_(4)的动量,进而通过动量守恒得到第3个碎片的动量.通过分析3个碎片的动能及解离的动能释放鉴别出未被探测的碎片为中性H原子的事件.借助Dalitz图、Newton图以及碎片产物的角分布等分析了该通道的动力学机制.结果表明,次序解离是该解离通道的主要机制,在碎裂过程中二价母体离子先解离成H^(+)和C_(3)H_(4),中间体的C_(3)H_(4)离子再进一步解离成C_(3)H_(4)和H原子.

The experiment on collision between 50-keV/u Ne^(8+) ion and C_(3)H_(4) molecule is carried out by reaction microscopic imaging spectrometer.The process of forming the C_(3)H_(4) divalent ion from propylene(CH_(2)CCH_(2)) and proacetylene(CH^(+)CCH) and then dissociating to produce H^(+) and C_(3)H_(4)C_(3)H_(4) ions and H atom is studied.Using the reaction microscope,the momentum vector of H^(+)ion and the momentum vector of C_(3)H_(4) ion are directly obtained,and then the momentum of the undetected fragment is reconstructed according to momentum conservation.By analyzing the kinetic energy of the three fragments and the total kinetic energy released from the dissociation process,the events with H atom as the third fragment are discriminated from H^(+),and thus the H^(+)ion,C_(3)H_(4) ion,and H atom are identified.In addition,it is found that the sequential fragmentation pathway in which H^(+) ion and C_(3)H_(4) ion are produced in the first step followed by dissociation of C_(3)H_(4) into C_(3)H_(4) ion and H atom in the second step is the dominant dissociation mechanism according to the detailed analyses of the Dalitz plot,Newton diagram andαdistribution.