Electronic structure and spectra of N-methylfullerenepyrrolidine

A quantum-chemical analysis of the donor-acceptor properties of a C 60 + dimethylenemethylamine binary system is performed. It is shown that the term of the intermolecular interaction is two-well, because of which the optimization of the system structure at the initial distances between the molecules of 0.21 nm or smaller leads to the formation of N- methylfullerenepyrrolidine C60. At initial distances exceeding 0.25 nm, a weakly bound charge transfer complex with almost complete retention of the properties of the individual molecules is formed. The low-temperature emission and absorption vibronic spectra of N-methylfullerenepyrrolidine C60 in the crystalline toluene matrix are studied experimentally. It is found that the absorption spectra of the fulleroid and pure fullerene in the region corresponding to the excitation of the lowest electronic states are generally similar. The difference observed between the low-frequency spectra agrees completely with the quantum-chemical analysis performed. © Nauka/Interperiodica 2007

Electronic structure and spectra of N-methylfullerenepyrrolidine

A quantum-chemical analysis of the donor-acceptor properties of a C 60 + dimethylenemethylamine binary system is performed. It is shown that the term of the intermolecular interaction is two-well, because of which the optimization of the system structure at the initial distances between the molecules of 0.21 nm or smaller leads to the formation of N- methylfullerenepyrrolidine C60. At initial distances exceeding 0.25 nm, a weakly bound charge transfer complex with almost complete retention of the properties of the individual molecules is formed. The low-temperature emission and absorption vibronic spectra of N-methylfullerenepyrrolidine C60 in the crystalline toluene matrix are studied experimentally. It is found that the absorption spectra of the fulleroid and pure fullerene in the region corresponding to the excitation of the lowest electronic states are generally similar. The difference observed between the low-frequency spectra agrees completely with the quantum-chemical analysis performed. © Nauka/Interperiodica 2007

Vibronic resonance in spectra of frozen solutions of the C60 fullerene derivatives

This paper reports on a study by site-selective laser spectroscopy of low-temperature broadband fluorescence spectra of N-methyl-2-(3,5-di-tert-butyl-4-hydroxyphenyl)-[C60] fulleropyrrolidine (N-MBHPhFP fullerene) molecules embedded in the crystalline toluene matrix. It has been shown that monochromatic laser excitation in the region of vibrational satellites of the pure electronic absorption band initiates structurization of the emission band of a pure electronic transition, which suggests the existence of a set of impurity centers in the crystalline host matrix. An analysis has been made of the factors accounting for replacement of the wide, inhomogeneously broadened band by a series of narrow bands, with the most essential of them being the weakness of electron-phonon coupling in the impurity center, the absence of electronic excitation transfer between the centers, and the vibronic resonance in the excited state of the set of centers. Vibration frequencies of the N-MBHPhFP fullerene in the excited electronic state have been determined. © 2011 Pleiades Publishing, Ltd

Vibronic resonance in spectra of frozen solutions of the C60 fullerene derivatives

This paper reports on a study by site-selective laser spectroscopy of low-temperature broadband fluorescence spectra of N-methyl-2-(3,5-di-tert-butyl-4-hydroxyphenyl)-[C60] fulleropyrrolidine (N-MBHPhFP fullerene) molecules embedded in the crystalline toluene matrix. It has been shown that monochromatic laser excitation in the region of vibrational satellites of the pure electronic absorption band initiates structurization of the emission band of a pure electronic transition, which suggests the existence of a set of impurity centers in the crystalline host matrix. An analysis has been made of the factors accounting for replacement of the wide, inhomogeneously broadened band by a series of narrow bands, with the most essential of them being the weakness of electron-phonon coupling in the impurity center, the absence of electronic excitation transfer between the centers, and the vibronic resonance in the excited state of the set of centers. Vibration frequencies of the N-MBHPhFP fullerene in the excited electronic state have been determined. © 2011 Pleiades Publishing, Ltd

Shpolski effect in optical spectra of frozen solutions of the organic C60 fullerene derivative in toluene

The optical spectra of a solution of the C60 ethyl acetate (C60-EA) in toluene are investigated. The absorption spectra measured at T = 80 K reveal a combination of an intense featureless background pedestal deriving from absorption of charge-transfer cluster complexes on which weakly structured molecular absorption is superposed. A decrease in the temperature from 80 to 2 K leads to the appearance of a multiplet of narrow lines (with a width of down to 5 cm-1) corresponding to the optical excitation of C60-EA molecules occupying different inequivalent positions in the matrix. A similar structure is observed in the luminescence spectrum of the C60-EA solution at T = 2 K. The structural luminescence spectrum is in mirror symmetry with the absorption bands. The frequencies of the corresponding transitions and the related molecular vibrations are determined. The allowed character of both mirror-symmetry spectra combined with the exact matching of their constituent frequencies suggests that the vibronic interaction in the molecule is determined by the Frank-Condon mechanism. © 2009 Pleiades Publishing, Ltd

Shpolski effect in optical spectra of frozen solutions of the organic C60 fullerene derivative in toluene

The optical spectra of a solution of the C60 ethyl acetate (C60-EA) in toluene are investigated. The absorption spectra measured at T = 80 K reveal a combination of an intense featureless background pedestal deriving from absorption of charge-transfer cluster complexes on which weakly structured molecular absorption is superposed. A decrease in the temperature from 80 to 2 K leads to the appearance of a multiplet of narrow lines (with a width of down to 5 cm-1) corresponding to the optical excitation of C60-EA molecules occupying different inequivalent positions in the matrix. A similar structure is observed in the luminescence spectrum of the C60-EA solution at T = 2 K. The structural luminescence spectrum is in mirror symmetry with the absorption bands. The frequencies of the corresponding transitions and the related molecular vibrations are determined. The allowed character of both mirror-symmetry spectra combined with the exact matching of their constituent frequencies suggests that the vibronic interaction in the molecule is determined by the Frank-Condon mechanism. © 2009 Pleiades Publishing, Ltd