The assignment of fundamental vibrations of BEDT-TTF and BEDT-TTF-d8

Kozlov, Mikhail E.; Pokhodnia, K. I.; Yurchenko, A. A.

doi:10.1016/0584-8539(87)80112-5

Cited by 149 publications

(85 citation statements)

References 6 publications

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“…A normal mode analysis of BEDT-TTF 0 and BEDT-TTF 1+ was reported by Kozlov et al [42,43]. The normal modes most sensitive to the charge (valence) of the BEDT-TTF molecule are the in-phase (ν 2 , Raman active) and out-of-phase (ν 27 infrared active) stretching modes of the ring C=C bonds, and the stretching mode of the C=C bond bridging two five member rings (ν 3 , Raman active).…”

Section: Charge-sensitive Mode Of Bedt-ttfmentioning

confidence: 99%

Infrared and Raman Studies of Charge Ordering in Organic Conductors, BEDT-TTF Salts with Quarter-Filled Bands

Yakushi

2012

Crystals

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This paper reviews charge ordering in the organic conductors, β″-(BEDT-TTF) (TCNQ), θ-(BEDT-TTF) 2 X, and α-(BEDT-TTF) 2 X. Here, BEDT-TTF and TCNQ represent bis(ethylenedithio)tetrathiafulvalene and 7,7,8,8-tetracyanoquinodimethane, respectively. These compounds, all of which have a quarter-filled band, were evaluated using infrared and Raman spectroscopy in addition to optical conductivity measurements. It was found that β″-(BEDT-TTF)(TCNQ) changes continuously from a uniform metal to a chargeordered metal with increasing temperature. Although charge disproportionation was clearly observed, long-range charge order is not realized. Among six θ-type salts, four compounds with a narrow band show the metal-insulator transition. However, they maintain a large amplitude of charge order (Δρ~0.6) in both metallic and insulating phases. In the X = CsZn(SCN) 4 salt with intermediate bandwidth, the amplitude of charge order is very small (Δρ < 0.07) over the whole temperature range. However, fluctuation of charge order is indicated in the Raman spectrum and optical conductivity. No indication of the fluctuation of charge order is found in the wide band X = I 3 salt. In α-(BEDT-TTF) 2 I 3 the amplitude of charge order changes discontinuously from small amplitude at high temperature to large amplitude (Δρ max~0 .6) at low temperature. The long-range chargeordered state shows ferroelectric polarization with fast optical response. The fluctuation of multiple stripes occurs in the high-temperature metallic phase. Among α-(BEDT-TTF) 2 MHg(SCN) 4 (X = NH 4 , K, Rb, Tl), the fluctuation of charge order is indicated only in the X = NH 4 salt. α′-(BEDT-TTF) 2 IBr 2 shows successive phase transitions to the ferroelectric state keeping a large amplitude of charge order (Δρ max~0 .8) over the whole temperature range. It was found that the amplitude and fluctuation of charge order in these compounds is enhanced as the kinetic energy (bandwidth) decreases. OPEN ACCESSCrystals 2012, 2 1292

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Section: Charge-sensitive Mode Of Bedt-ttfmentioning

confidence: 99%

Infrared and Raman Studies of Charge Ordering in Organic Conductors, BEDT-TTF Salts with Quarter-Filled Bands

Yakushi

2012

Crystals

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“…Moderate modification of the spectrum is observed in the region of bending and wagging modes of CH 2 groups of the ET molecules (Table). The bands 1415 and 1426 cm-1 (8 CH2) and 1289 cm-1 (ω2 CH2) are shifted by 6 _ 9 cm -1 in relation to frequencies observed for pristine ET [16]. These shifts are higher than those observed for ET single crystals grown from CS2.…”

Section: Resultsmentioning

confidence: 42%

“…Apart from the saturated absorptions, strong and very broad absorption peaked at 1508 cm -1 , characteristic of the solvent can be seen. The frequencies of the observed lines of C60/CS2, ET/CS2 and (ET)2C60/CS2 single crystals, and for compariSon the frequencies of the pristine ET KBr pellet recorded by Kozlov et al [16] are listed in Table. The spectrum of C60/CS2 clathrate is very rich and exhibits strong bands typical of the broken I, symmetry of the genuine, original fullerene. The carbon disulfide is a very good solvent of fullerene and the occurrence of numerous CS2 molecules in the clathrate structure seems normal.…”

Section: Resultsmentioning

confidence: 99%

Infrared Absorption in Single Crystals of (ET)₂C₆₀Grown from CS₂Solution

1995

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Fourier transform IR absorption spectra of single crystals of the (ET)2 C60 complex grown from the CS2 solution as well as its components:C60 and ET, also grown from CS 2 solution, are presented and discussed. It is shown that the rotation of C60 is strongly hindered and ET molecules are bent in the crystal structure of the complex. The arguments for the domination of the van der Waals interactions are given.

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“…res of this method, principal attention was focused on proving the adequacy of a chosen valence force field (VFF) for the description of molecular vibration in this class of donors. The variant of VFF proposed in our earlier work for BEDT-TTF and its deuteroanalogue [6] was easily adopted for substituted terminal groups BMDT-TTF (bis(methylenedithio)TTF) [7] including the case of its cation radicals [9] and for S -3 O substituted BEDO-TTF [8].…”

Section: Resultsmentioning

confidence: 99%

Electron-Molecular Vibration Coupling in TTF-Based Donors

Pokhodnia¹

1995

Acta Phys. Pol. A

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BEDT-TTF, BMDT-TTF and BEDO-TTF are well known thio-TTF and oxo-TTF (in the former case) derivatives on the basis of which cation--radical salts with 2D type of conductivity can be produced. In this work the comparative analysis of electron-molecular vibration coupling constants (obtained by MNDO quantum-chemical method) that describe the interaction between totally symmetric A g modes and electron on HOMO level is performed.

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The assignment of fundamental vibrations of BEDT-TTF and BEDT-TTF-d8

Cited by 149 publications

References 6 publications

Infrared and Raman Studies of Charge Ordering in Organic Conductors, BEDT-TTF Salts with Quarter-Filled Bands

Infrared and Raman Studies of Charge Ordering in Organic Conductors, BEDT-TTF Salts with Quarter-Filled Bands

Infrared Absorption in Single Crystals of (ET)₂C₆₀Grown from CS₂Solution

Electron-Molecular Vibration Coupling in TTF-Based Donors

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The assignment of fundamental vibrations of BEDT-TTF and BEDT-TTF-d8

Cited by 149 publications

References 6 publications

Infrared and Raman Studies of Charge Ordering in Organic Conductors, BEDT-TTF Salts with Quarter-Filled Bands

Infrared and Raman Studies of Charge Ordering in Organic Conductors, BEDT-TTF Salts with Quarter-Filled Bands

Infrared Absorption in Single Crystals of (ET)2C60Grown from CS2Solution

Electron-Molecular Vibration Coupling in TTF-Based Donors

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Infrared Absorption in Single Crystals of (ET)₂C₆₀Grown from CS₂Solution