The Origin of UV Band Structure

The nitrosonium cation bears a formal relationship to the well-studied halogens (i.e. X2 = I2, Br2, and Cl2), with both classes of structurally simple diatomic electron acceptors forming an extensive series of intermolecular electron donor-acceptor (EDA) complexes that show well-defined charge-transfer absorption bands in the UV-visible spectral region. Mulliken (1952a,b 1964 Mulliken and Person, 1969) originally identified the three possible nonbonded structures of the halogen complexes as in Chart 7, and the subsequent X-ray studies established the axial form II to be extant in the crystals of the benzene complexes with Cl2 and Br2 (Hassel and Stromme, 1958, 1959). In these 1 1 molecular complexes, the closest approach of the... 

Early studies of the B1Ai(tc,tc ) <— X A n2) or S2 < S0 room-temperature absorption spectrum were carried out by Famworth and King [32], and then later in emission by Steer and co-workers [21]. Detailed analyses of the hot band structure were made by Judge and Moule [33], who located the origin for the system and identified several band progressions. In the course of recording the Sj S0. LIF excitation spectrum, Clouthier et al. [26] observed a UV emission... 

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