Structural and dynamical investigation of glassforming smectogen by X-ray diffraction and infra-red spectroscopy aided by density functional theory calculations
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arXiv
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| Autori principali: | , , , |
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| Natura: | Preprint |
| Pubblicazione: |
2024
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| _version_ | 1866915101742727168 |
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| author | Deptuch, Aleksandra Górska, Natalia Baran, Stanisław Urbańska, Magdalena |
| author_facet | Deptuch, Aleksandra Górska, Natalia Baran, Stanisław Urbańska, Magdalena |
| contents | Molecular arrangement in the chiral smectic phases of the glassforming (S)-4'-(1-methylheptylcarbonyl)biphenyl-4-yl 4-[7-(2,2,3,3,4,4,4-heptafluorobutoxy) heptyl-1-oxy]benzoate is investigated by X-ray diffraction. An increased correlation length of the positional short-range order in the supercooled state agrees with the previous assumption of the hexatic smectic phase. However, the registered X-ray diffraction patterns are not typical for the hexatic phases. Comparison of the smectic layer spacing and optical tilt angle indicates a strongly non-linear shape of molecules, which enables choice of the molecular models obtained by DFT calculations, used subsequently to interpret the infra-red spectra. The presumption of the hexatic smectic FA* or IA* phase is supported by the splitting of the absorption bands related to the C=O stretching in the supercooled state, which is absent in the smectic CA* phase above the melting temperature. The glass transition affects the temperature dependence of the smectic layer spacing but only subtly impacts the infra-red spectra. Application of the k-means cluster analysis enables distinction between the infra-red spectra below and above the glass transition temperature, but only for certain spectral ranges. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2409_08654 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Structural and dynamical investigation of glassforming smectogen by X-ray diffraction and infra-red spectroscopy aided by density functional theory calculations Deptuch, Aleksandra Górska, Natalia Baran, Stanisław Urbańska, Magdalena Soft Condensed Matter Materials Science Molecular arrangement in the chiral smectic phases of the glassforming (S)-4'-(1-methylheptylcarbonyl)biphenyl-4-yl 4-[7-(2,2,3,3,4,4,4-heptafluorobutoxy) heptyl-1-oxy]benzoate is investigated by X-ray diffraction. An increased correlation length of the positional short-range order in the supercooled state agrees with the previous assumption of the hexatic smectic phase. However, the registered X-ray diffraction patterns are not typical for the hexatic phases. Comparison of the smectic layer spacing and optical tilt angle indicates a strongly non-linear shape of molecules, which enables choice of the molecular models obtained by DFT calculations, used subsequently to interpret the infra-red spectra. The presumption of the hexatic smectic FA* or IA* phase is supported by the splitting of the absorption bands related to the C=O stretching in the supercooled state, which is absent in the smectic CA* phase above the melting temperature. The glass transition affects the temperature dependence of the smectic layer spacing but only subtly impacts the infra-red spectra. Application of the k-means cluster analysis enables distinction between the infra-red spectra below and above the glass transition temperature, but only for certain spectral ranges. |
| title | Structural and dynamical investigation of glassforming smectogen by X-ray diffraction and infra-red spectroscopy aided by density functional theory calculations |
| topic | Soft Condensed Matter Materials Science |
| url | https://arxiv.org/abs/2409.08654 |