摘要
通过激光溅射固体样品，产生了ⅤＢ簇元素的杂碳团簇ＣｎＸ－（Ｘ＝Ｎ，Ｐ，Ａｓ，Ｓｂ和Ｂｉ）．随着从Ｎ到Ｂｉ的变化，ＣｎＸ－的奇偶效应也产生了由奇强偶弱变化到偶强奇弱变化．根据Ｐｉｔｚｅｒ等人提出的杂化轨道理论和Ｈｕｃｋｌｅ模型，结合ⅤＢ簇元素性质的变化规律，对实验现象给予了可能的解释：本文认为ＣｎＮ团簇取直链构型（∶Ｃ≡Ｃ—Ｃ≡Ｃ···Ｃ≡Ｎ∶），Ｃｎ与Ｎ之间形成共价键；对于ＣｎＢｉ团簇，Ｃｎ与Ｂｉ之间可能形成离子键（Ｃｎ仍为类似聚炔的直链共轭体系）；对于其它三种团簇可能存在Ｃｎ与Ｘ之间离子键与共价键共振，随着电负性由大到小，共价键成分逐渐减弱，而离子键成分逐渐增强，因此出现了奇偶效应的变化．
Group V B element carbide ions CnX- (X=N,P,As,Sb and Bi) were produced by laser irradisting solid samples. The parity effects of CnX- ions change with stronger emission intensities from odd n to even n when we go down the group from N to Bi. It is believed that CnX- cluster ions take a linear chain structure like polyacetylene, and that the covalent bond is taken between Cx and N for cluster ions CnN-;the ionic bond between Cn and Bi for cluster ions CnBi- and the ionic-covalent resonance for cluster ions CnX- (X=P,As and Bb).The experiment results in Pitzer et al.(sp hybridization of linear chains) and Huckle model as well as the change of the properities of the group VB elements areexplained.
基金
国家自然科学基金
重点实验室开放课题
关键词
奇偶效应
直链共轭结构
杂碳团簇离子
激光溅射
the parity effects
linear chains of polyacetylene-like
hetero-carbon cluster ions
