Study of solvent effects on the molecular structure and the reorganization energies of 4-nitro-4'-dimethylaminoazobenzene using resonance Raman intensities

Biswas, Nandita ; Umapathy, Siva (2001) Study of solvent effects on the molecular structure and the reorganization energies of 4-nitro-4'-dimethylaminoazobenzene using resonance Raman intensities Journal of Raman Spectroscopy, 32 (6-7). pp. 471-480. ISSN 0377-0486

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Official URL: http://onlinelibrary.wiley.com/doi/10.1002/jrs.747...

Related URL: http://dx.doi.org/10.1002/jrs.747

Abstract

Resonance Raman Spectroscopy was used to probe the effect of solvent polarity on the molecular structure and isomerization dynamics of 4-nitro-4'-dimethylaminoazobenzene (DA); in addition; the influence of the polarity and the relaxation behavior of the solvent on the mode-specific vibrational and solvent reorganization energies was investigated. Raman spectra were recorded in solvents with different polarity parameters, n-hexane and benzene, using 11 excitation wavelengths in the range 450-550 nm, scanning every 10 nm using the tunable laser pulse output of an optical parametric oscillator. It was observed that the solvent polarity plays a major role in influencing the excited-state potential energy surfaces of DA. The plot of resonance Raman intensities versus excitation wavelength (Raman excitation profiles) of the Franck-Condon-active fundamentals of DA Shows that in n-hexane, the locally excited state is more favorable than that in benzene where the charge-transfer state is more stable. The distortions along the N =N and C-N stretching vibrations of DA in n-hexane and benzene infer isomerization via rotation in n-hexane and inversion in benzene. The increase in solvent and vibrational reorganization energies with increasing solvent polarity parameter suggests greater distortion in the Franck-Condon excited state following photoexcitation.

Item Type:Article
Source:Copyright of this article belongs to John Wiley and Sons.
ID Code:64963
Deposited On:15 Oct 2011 12:37
Last Modified:15 Oct 2011 12:37

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