Etude cristallographique de la transition de phase du benzil

Odou, G.; More, M.; Warin, V.

doi:10.1107/s0567739478014540

Cited by 31 publications

(13 citation statements)

References 6 publications

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“…83 K) presenting particularly interesting structural, electrical, and mechanical properties. 20,[48][49][50][51][52][53][54][55][56][57][58] However, to the best of our knowledge, no vibrational spectroscopic studies have been performed on gaseous benzil or for the compound isolated in a low-temperature inert matrix.…”

Section: Introductionmentioning

confidence: 99%

Matrix-Isolation FTIR Spectroscopy of Benzil: Probing the Flexibility of the C−C Torsional Coordinate

et al. 2004

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The infrared spectrum and conformational flexibility of benzil, (C 6 H 5 CO) 2 , are studied by matrix-isolation FTIR spectroscopy, supported by DFT calculations. It is shown that the low-frequency (ca. 25 cm -1 ), largeamplitude torsion around the C-C central bond strongly affects the structural and spectroscopic properties exhibited by the compound. The equilibrium conformational distribution of molecules with different OdC-CdO dihedral angles, existing at room temperature in the gas phase, and trapped in a low-temperature (T ) 9 K) inert matrix can be changed either by in situ irradiation with UV light (λ > 235 nm) or by annealing the matrix to higher temperatures (T ≈ 34 K). In the first case, the increase of the average OdC-CdO angle results from conformational relaxation in the excited electronic states (S 1 and T 1 ), whose lowest-energy conformations correspond, for both S 1 and T 1 states, to a nearly planar configuration with the OdC-CdO dihedral angle equal to 180°. In the second case, the decrease of the average value of the OdC-CdO dihedral angle is a consequence of the change in the S o C-C torsional potential, resulting from interactions with the matrix media, which favors the stability of the more polar structures with smaller OdC-CdO dihedral angles.

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Section: Introductionmentioning

confidence: 99%

Matrix-Isolation FTIR Spectroscopy of Benzil: Probing the Flexibility of the C−C Torsional Coordinate

et al. 2004

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“…Such behavior is usually associated with a first-order phase transition. Our experiment therefore provided non-thermodynamic evidence for the first-order nature of the phase transition in benzil, which was then in dispute [63]. Benzil offers us a rare opportunity to investigate phase transition by magnetic resonance.…”

Section: Magnetic Resonance Under Extreme Conditionsmentioning

confidence: 89%

Magnetic resonance studies of triplet carbonyls

Chan

1987

Reviews of Chemical Intermediates

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“…It first occurs at the М point of the BZ boundary, as it is induced by con densation of the soft TA branch and it is only later that acoustics and optics in the center of the BZ ease through the appreciable interaction between the order parameter and deformation observed in various exper iments [3][4][5][6][7][8][9][10]. The interpretation of the mechanism of phase transitions in benzil crystals proposed in this study is consonant with the models of transitions in nonintrinsic segnetoelastics Hg 2 Hal 2 (Hal = Cl, Br, I), which are used as the model crystals when studying general problems of structural phase transitions (e.g., [11]).…”

Section: Discussionmentioning

confidence: 99%

“…Organic quartz (benzil) is used as the model organic crystal when studying general problems of lattice dynamics and structural phase transitions. Unfortunately, however, the model of this transition proposed in [8] was based on the results from X ray studies [9] that subsequently turned out to be erroneous [3] and contradicted a number of experimental facts, thus requiring certain corrections to be made. There was thus a demand for performing new experiments aimed at studying the phase transi tion effects in benzil crystals, mainly using X ray dif fraction analysis.…”

Section: Introductionmentioning

confidence: 99%

The phase-transition order parameter, fluctuations, and nanoclusters in benzil crystals

Markov

Roginskiĭ

2013

Bull. Russ. Acad. Sci. Phys.

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Bragg and diffuse X ray reflections from the M points of the Brillouin zone boundary of a benzil crystal paraphrase, the integral intensity of which is associated with the order parameter and its fluctuations, are studied. Original data on the temperature behavior of the order parameter and diffuse scattering are obtained. The relevant critical exponents are determined. A conclusion is drawn as to the proximity of the phase transition in these crystals to the tricritical point. A phase transition model is discussed.

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Etude cristallographique de la transition de phase du benzil

Cited by 31 publications

References 6 publications

Matrix-Isolation FTIR Spectroscopy of Benzil: Probing the Flexibility of the C−C Torsional Coordinate

Matrix-Isolation FTIR Spectroscopy of Benzil: Probing the Flexibility of the C−C Torsional Coordinate

Magnetic resonance studies of triplet carbonyls

The phase-transition order parameter, fluctuations, and nanoclusters in benzil crystals

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