Bromine, resonance Raman

Atabek, O., Lefebvre, R., and Jacon, M. (1980b). Continuum resonance Raman scattering of light by diatomic molecules. II. Theoretical study of the Q branches of An = 1 profiles of molecular bromine, J. Chem. Phys. 72, 2683-2693. 

Hartke, B. (1991). Continuum resonance Raman scattering in bromine comparison of time-dependent calculations with time-independent and experimental results, J. Raman Spec. 22, 131-140. 

Raman spectra of chlorine, bromine, and iodine gas were first recorded by Flolzer et al. (1970) with argon laser excitation, the latter two halogens showed a strong resonance Raman effect. The numerous results of later investigations are presented in Sec. 6.1. on the resonance Raman effect. 

Also linear chain complexes such as Pt(etn)4Cl3 which is known colloquially as Wolf-fram s red (etn being an abbreviation for ethylamine) have been studied successfully by resonance Raman spectroscopy (Clark, 1984). As example, we show in Fig. 6.1-12 the resonance Raman spectrum of a related halogen-bridged linear-chain species, [Pt(pn)2] [Pt(pn)2Br2] [Cu3Br5]2 (Clark et al., 1980). Although this species contains a complicated copper bromine chain, the resonance Raman spectrum (Fig. 6.1-12) is completely dominated by bands attributed to the v fundamental and its overtones n U[ of the platinum-bromine chain. 

The very different spectra of iodine obtained under continuum and discrete resonance-Raman conditions are illustrated in Fig. 11 for resonance with the B state, whose dissociation limit is 20,162 cm . In the case illustrated of discrete resonance-Raman scattering, Xl =514.5 nm, and specific re-emission results from an initial transition from the v" = 1 vibrational, J" = 99 rotational level of the X state to the v = 58, J = 100 level of the B state, i.e. the transition is 58 - l" R(99). Owing to the rotational selection rule for dipole radiation, AJ = 1, a pattern of doublets appears in the emission. Clearly, the continuum resonance-Raman spectrum of iodine (Xl = 488.0 nm) is very different from the discrete case spectrum. The structure, which arises from the 0,Q, and S branches of the multitude of vibration-rotation transitions occurring, can be analysed in terms of a Fortrat diagram, as done for gaseous bromine (67). 

Thus, if the monochromator is set to a wavenumber of 650cm", the formation of the C—Br bond can be recorded as a function of time during a chemical reaction between bromine and an olefin. Buehler used this method to follow the bromine/octadecene reaction. It should be pointed out that the Raman scattering is a function of droplet size as well as composition, and unlike bulk Raman it is complicated by the morphological resonances... 

Fig. 48. The elastic resonance spectrum and the Raman signal during the bromination of 1-octadecene (from Buehler, 1991).

---