Spectroscopy of amorphous substances with molecular structure

Sheka, E.F.

doi:10.3367/ufnr.0160.199002c.0263

Cited by 15 publications

(4 citation statements)

References 39 publications

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“…Evidence for shorter inter-planar spacing and close molecular packing in metastable phases has also been reported for some nematogenic compounds. 17,28 An important inference could immediately be drawn from a close examination of Figs 1 and 2, that the splitting of the band at ca 975 cm~1, characteristic of the SÈM transition at 47 K, does not follow identical temperature dependences during cooling and heating cycles.…”

Section: Resultsmentioning

confidence: 99%

A new phase transition in supercooled TBDA probed by low-temperature Raman study

Dash

Singh

Asthana

et al. 1999

J. Raman Spectrosc.

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Raman spectra of terephthalidenebis-p-n-decylaniline (TBDA) were recorded in the regions 925-1000 and 1120-1220 cm-1 from room temperature down to 20 K during both cooling and heating cycles. The subtle changes in the spectral features of the bands at ca 975 and ca 1195 cm-1 at 47 K were attributed to a hitherto unreported stable-metastable phase transition in TBDA. The dynamics of the new phase transition are explained in terms of splitting of the non-planar mode at ca 975 cm-1 due to strong steric hindrances caused by increased intermolecular interactions due to close packing in the low-temperature phase.

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Section: Resultsmentioning

confidence: 99%

A new phase transition in supercooled TBDA probed by low-temperature Raman study

Dash

Singh

Asthana

et al. 1999

J. Raman Spectrosc.

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“…Because of close molecular packing, strong intermolecular interactions between di erent Schi 's base linkages, (± CH5 N± ), which play a vital role in the S± M modi® cation due to their random orientation [11], and subsequent planar modi® cation of the benzene rings [26], possibly results in partial splitting of the n u ± N mode at~1195 cm Õ 1 . Evidence of shorter inter-planar spacing and close molecular packing in metastable phases has also been reported for some nematogenic compounds [17,28].…”

Section: Low Temperature Raman Spectra and Evidence Of An S± M (Stablmentioning

confidence: 60%

Dynamics of a low temperature phase transition in liquid crystal TB10A probed by Raman spectroscopy

Dash¹,

Alapati²,

Singh³

et al. 1999

Liquid Crystals

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Raman spectra of TB10A were recorded in the regions, 925± 1000 and 1140± 1220 cm Õ 1 from room temperature down to 20 K, during cooling and heating cycles. The subtle changes in the spectral features of the bands at~975 and~1195 cm Õ 1 at 47 K were attributed to a hitherto unreported stable± metastable phase transition in TB10A. The dynamics of the new phase transition have been explained in terms of splitting of the non-planar mode at 975 cm Õ 1 owing to strong intermolecular interaction due to close molecular packing in the low temperature phase. The spectral anomaly of the 975 cm Õ 1 band, in terms of variation of relative intensity with respect to temperature, also shows the hysterisis linked with the process of stable± metastable± stable modi® cation in TB10A.

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“…25 The polymorphism of amorphous compounds was studied. 99,100 The data published in the literature provide evidence that this phenomenon is typical of all structural forms of the condensed state.…”

Section: Discussionmentioning

confidence: 90%

Crystal structures of inorganic compounds with atomic defects

Frank-Kamenetskaya¹

2003

Russ. Chem. Rev.

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Main types of crystal structures with different atomic Main types of crystal structures with different atomic defects (point, volume, planar and linear) are considered using defects (point, volume, planar and linear) are considered using inorganic compounds as an example. The review presents the inorganic compounds as an example. The review presents the results of composite analysis of such real structures. Their results of composite analysis of such real structures. Their symmetry, ordering, ways of description, nomenclature and the symmetry, ordering, ways of description, nomenclature and the possibility of the diagnostics from diffraction patterns are dis-possibility of the diagnostics from diffraction patterns are discussed. The results of studies provide evidence that polymorphism cussed. The results of studies provide evidence that polymorphism is typical of real crystal structures. The bibliography includes 101 is typical of real crystal structures. The bibliography includes 101 references references. .

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Spectroscopy of amorphous substances with molecular structure

Cited by 15 publications

References 39 publications

A new phase transition in supercooled TBDA probed by low-temperature Raman study

A new phase transition in supercooled TBDA probed by low-temperature Raman study

Dynamics of a low temperature phase transition in liquid crystal TB10A probed by Raman spectroscopy

Crystal structures of inorganic compounds with atomic defects

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