与键角有关的叠氮化银的位能面和无辐射跃迁

Angular dependence of potential and non-radiatin transition of AgN_3

用考虑到电子相关能的量子化学从头算方法 (MC CEPA ,ACPF和CEPA)计算了键叠氮化银Ag N与N N间面内与面外不同键角和面外一定的键角沿着AgNNN间的距离R2 几个最低的激发态和基态单态的势能曲线。两个最低的三重态的势能曲线在R2 =3.392 (a .u)附近与基态单态的相交提供了标准的光化学反应学家所谓的无辐射跃迁势能面形式。而这交点的位置恰与光解反应的1.4～ 1.8eV高的反应势垒的位置 R2 =3.192 (a.u)相近 ,且势垒仅略有增高。故而B .P .Aduev在热解的同时观察到了化学发光现象。并发现叠氮基的面外弯曲的垂直跃迁矩要比面内弯曲和键长变化方式的跃迁矩大得多 ;

Using the coupled electron potential algorithms in quantum chemistry, MC CEPA(many configuration coupled electron pair),ACPF(Average coupled electron pair function), and CEPA(coupled electron pair), we have calculated the lowest electronic states of AgN 3 as functions of the in and out plane bond angles (AgNN N) By and Bx and of bond length R 2(bond (AgNN N) at out plane bond angle  B x=5°.  The potential curve intersections at R 2=3.392a.u.between those of single state (ground state) and two triplet states make non radiation transition of AgN 3 possible, and the points of intersection are close to the points (R 2=3.192a.u.) at which there are potential barriers (1.4～1.8?eV high) of the photo dissociation. That is the reason why the thermo decomposition and photo dissociation of AgN 3 are observed at the same time in reference [7]. The barrier of non radiation transition is higher than that of photo dissociation. The perpendicular transition moments along the potential curve dependent on out plane bond angle is larger than that dependent on other bond angles and bond lengths. The stable cis and anti structure of excited states are discussed.