复合物Mg＋-NCSCH3, Ca＋-NCSCH3光解离光谱研究

研究了复合物Mg^＋-NCSCH₃在230～440 nm波段和Ca^＋-NCSCH₃在320～560 nm波段的光解离光谱. 复合物Mg^＋-NCSCH₃, Ca^＋-NCSCH₃光诱导反应的产物质谱表明有非反应猝灭产物Mg^＋(Ca^＋), C—S键断裂产物Mg^＋(Ca^＋)NC 和Mg^＋(Ca^＋)NCS以及重排反应产物Mg^＋(Ca^＋)-CHSH通道. 在原子跃迁谱线(3²S→3²P, 对于Mg^＋; 4²S?4²P, 对于Ca^＋)的红和蓝两边, Mg^＋-NCSCH₃的光解离光谱由两个宽峰组成; 而对于Ca^＋-NCSCH₃, 则是由三个谱峰构成. CIS/6-311＋＋G^**等级上, 对应于基态构型的Mg^＋-NCSCH₃电子态跃迁能量和振子强度与实验光谱较为一致; 而Ca^＋-NCSCH₃有较大的差别. 这是因为CIS方法忽略电子相关效应, 而Ca^＋-based的跃迁中3d和4s轨道间存在较强的混合所致.

Photodissociation Spectra of the Complexes Mg+-NCSCH3 and Ca+-NCSCH3

Photodissociation spectra of the complexes Mg^＋-NCSCH₃ in the spectral region of 230～440 nm and Ca^＋-NCSCH₃ in 320～560 nm were studied. Mass spectra of the products of photo-induced reaction of the complexes Mg^＋-NCSCH₃ and Ca^＋-NCSCH₃ exhibits the presence of Mg^＋(Ca^＋) from nonreaction quenching, Mg^＋(Ca^＋)NC and Mg(Ca^＋)^＋NCS from the rupture of S-C bonds, and rearrangement products Mg^＋(Ca^＋)-CHSH. The photodissociation spectra consist of two broad peaks for Mg^＋-NCSCH₃, and three broad peaks for Ca^＋-NCSCH₃ on the red and blue sides of atomic transition (3²S→3²P for Mg^＋; 4²S→4²P for Ca^＋). The calculated absorption spectrum corresponding to the minimum-energy structure agrees well with the experimental spectrum for Mg^＋-NCSCH₃, but poorly for Ca^＋-NCSCH₃. The reasons are that CIS method neglected correlation effects and orbital mixing occured between 3d and 4s during Ca^＋-based transition.