THE RESONANCE RAMAN SPECTRA OF $CrO^{2-}_{4}$ AND $I^{-}_{3}$

Abstract

Using the rotating Raman sample technique for liquids (Appl. Spectr., 25, 500 (1971)) and for crystal powders (Appl. Spectr., 25, 609 (1971)) and the two UV laser lines of an argon ion laser at 3511 {\AA} and 3638 {\AA} we have been able to investigate the resonance Raman effect of the $CrO^{2-}_{4}$ and the $I^{-}_{3}$ ion. $CrO^{2-}_{4}$ : High overtone progressions of the totally symmetric vibration $\nu_{1}$ were observed which allow the determination of anharmonicity constants and estimates of the dissociation energy from the $\nu_{1}$ breathing mode. Relative intensities have been measured in the strong resonance case. Also preresonance intensity data were determined and discussed in terms of an existing theory. The overtone progression of $\nu_{1}$ shows a large increase in halfbandwidth with increasing vibrational quantum number. $I^{-}_{3}$: Solutions of $CsI_{3}$ and $KI + I_{2}$ in water show a strong resonance Raman effect of the $I^{-}_{3}$ ion. Again high intensity overtone progressions of the $\nu_{1}$ line are observed. This progression allowed us to confirm the presence of the $I^{-}_{3}$ ion in an $I_{2}$/Methanol solution at low iodine concentrations $(10^{-3} mole/1)^{3}$.