The photodissociation of NO＋ at c3∏（v′=0） state is studied by threshold photoelectron- photoion coincidence imaging method. By some assumptions, the relations between velocity in center of mass （CM） coordinates and most probable center of mass （MPCM） coordinates, time of flight and displacement in the velocity map image of fragment ions are derived using vector addition of velocity and displacement on the condition of perpendicular molecular beam. Using these relations the velocity in CM coordinates, the velocity and angular distri- bution of N＋ fragment ions in MPCM coordinates are obtained and discussed, respectively.
Vacuum ultraviolet photon-induced ionization and dissociation of isoleucine are investi- gated with synchrotron radiation photoionization mass spectroscopy and theoretical cal- culations. The main fragment ions at m/z=86, 75, 74, 69, 57, 46, 45, 44, 41, 30, 28, and 18 from isoleucine are observed in the mass spectrum at the photon energy of 13 eV. From the photoionization efficiency curves, appearance energies for the principal fragment ions CsH12N＋ （rn/z=86）, C2H5NO2＋ （m/z=75）, C5H9＋ （rn/z=-69）, C4H9＋ （m/z=57）, and CH4N＋ （m/z=30） are determined to be 8.844-0.07, 9.254-0.06, 10.20-4-0.12, 9.254-0.10, and 11.05＋0.07 eV, respectively, and possible formation pathways are established in detail by the calculations at the B3LYP/6-31＋＋G（d, p） levels. These proposed channels include simple bond cleavage reactions as well as reactions involving intermediates and transition structures. The experimental and computational appearance energies or barriers are in good agreement.
利用同步辐射光电离质谱装置,测量了Ar.CO范德瓦尔斯(van der Waals,vdW)团簇的的光电离质谱和光电离效率曲线.将它们与CO分子的绝对光吸收光谱比较,发现在13.9到14.6eV能量范围内的Ar.CO+的光电离效率曲线主要反映了收敛到CO+(X2Σ+,v′=1,2和3)Rydberg系列和收敛到CO+(A2Π)的n=3的振动序列(v′=6—9)的特点;在14.6—15.75eV光子能量范围内的Ar.CO的光电离效率曲线主要反映了CO的光吸收特性.然而,由于Ar和CO之间的相互作用,其中的5个重要的光谱结构发生了蓝移;而在15.75—15.80eV光子能量范围内的Ar-CO的光电离效率曲线,它的属性受到组分Ar和CO的共同影响.与此同时,也从理论上计算了Ar.CO团簇的电离能、Ar.CO团簇和Ar.CO+团簇离子的离解能.
