Structural dynamics of 4-formaldehyde imidazole and imidazole in light absorbing S sub(2)( pi pi ) state

The short-time structural dynamics of 4-formaldehyde imidazole and imidazole in light absorbing S sub(2)( pi pi *) state were studied by using resonance Raman spectroscopy and quantum mechanical calculations. The vibrational spectra and ultraviolet absorption spectra of 4-formaldehyde imidazole were...

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Bibliographic Details
Published in:Journal of Raman spectroscopy 2015-03, Vol.46 (3), p.293-301
Main Authors: Li, Dan, Zhao, Yan Ying, Xue, Jia-Dan, Zheng, Xuming
Format: Article
Language:English
Subjects:
Absorption
Charge
Dynamic structural analysis
Dynamics
Excitation
Imidazole
Mathematical analysis
Quantum mechanics
Raman spectroscopy
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Summary:The short-time structural dynamics of 4-formaldehyde imidazole and imidazole in light absorbing S sub(2)( pi pi *) state were studied by using resonance Raman spectroscopy and quantum mechanical calculations. The vibrational spectra and ultraviolet absorption spectra of 4-formaldehyde imidazole were assigned. The resonance Raman spectra of imidazole and 4-formaldehyde imidazole were obtained in methanol and acetonitrile with excitation wavelengths in resonance with the first intense absorption band to probe the short-time structural dynamics. complete active space self-consistent field calculations were carried out to determine the minimal singlet excitation energies and structures of S sub(1)(n pi *), S sub(2)( pi pi *), and conical intersection point S sub(1)(n pi *)/S sub( 2)( pi pi *). The results show that the A-band structural dynamics of imidazole is predominantly along the N sub(1)H/C sub(4)H/C sub(5 )H/C sub(2)H in-plane bending reaction coordinate, which suggests that excited state proton or hydrogen transfer reaction takes place somewhere nearby the Franck-Condon region. The significant difference in the short-time structural dynamics between 4-formaldehyde imidazole and imidazole is observed, and the underlying mechanism is interpreted in term of excited state charge redistribution. Copyright copyright 2015 John Wiley & Sons, Ltd. The structural dynamics of 4-formaldehyde imidazole and imidazole was studied by using resonance Raman spectroscopy and quantum mechanical calculations. The excited state proton transfer reaction of imidazle or 4-formaldehyde imidazole takes place somewhere nearby the Franck-Condon region. Charge redistribution reaction occurs between CH==O group and imidazole ring in the Franck-Condon region.
ISSN:0377-0486
1097-4555
DOI:10.1002/jrs.4633