Vibrational spectroscopic study of SiO2-based nanotubes |
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| Institution: | 1. Technische Universität München, Department of Chemistry, Molecular Catalysis, Catalysis Research Center, D-85747 Garching b. München, Germany;2. Research Institute of Chemical and Process Engineering, Faculty of Information Technology, University of Pannonia, H-8201 Veszprém, Hungary;3. Department of Materials and Environmental Chemistry, Stockholm University, SE-106 91 Stockholm, Sweden;4. Institute of Molecular Pharmacology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, H-1525 Budapest, Hungary;1. School of Materials Science and Engineering, Northeastern University, Shenyang 110004, China;2. State Key Laboratory of Baiyunobo Rare Earth Resource Researches and Comprehensive Utilization, Baotou Research Institute of Rare Earths, Baotou 014030, China;1. School of Physics & Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, UK;2. Department of Physics, Faculty of Science for Girls, King Abdulaziz University, Jeddah, Saudi Arabia;1. Moscow Institute of Physics and Technology (State University), Institutskiy Pereulok 9, Dolgoprudny 141700, Russia;2. A.M. Prokhorov General Physics Institute, Russian Academy of Sciences, Vavilov Str., 38, Moscow 119991, Russia;3. 1. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, Stuttgart 70550, Germany;4. Faculty of Physics, Southern Federal University, Bolshaya Sadovaya 105/42, Rostov-on-Don 344090, Russia;5. 1. Physikalisches Institut, Georg-August-Universität Göttingen, Fredrich-Hund-Platz 1, Göttingen 37077, Germany;6. Key Laboratory of Material Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031, People''s Republic of China;7. Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, Stuttgart 70569, Germany;8. Institute of Physics, ASCR Na Slovance 2, 18221 Prague 8, Czech Republic |
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| Abstract: | Novel organic–inorganic hybrid nanotubes containing silica and ethane (EtSNT), ethylene (ESNT) and acetylene (ASNT) units, as well as brominated ESNT (Br-ESNT) and glycine-modified Br-ESNT (Gly-ESNT) have been studied by IR and Raman spectroscopy. The results are compared with the spectral features for conventional silica nanotubes (SNT) and amorphous silica. Bands peculiar to organic moieties have been detected and assigned. Assignment of the silicate backbone vibrations was based on the results of normal coordinate calculations. Furthermore, characteristic silicate, so-called ‘nanotube’ vibrations have been identified and their band positions have been summarized to serve as a future reference for such compounds. SiOSi antisymmetric stretchings were observed in the range 1000–1110 cm−1, while the symmetric stretchings appeared between 760 and 960 cm−1 for EtSNT, ESNT and Br-ESNT.Force constants have been refined for models of the repeating structure units: O3SiOSi(OSi)3 for SNT and SiCHnCHnSi(OSi)3 for organosilica nanotubes (n = 2, EtSNT; n = 1, ESNT and n = 0, ASNT). The calculated SiO stretching force constants were increased from 4.79 to 4.88 and 5.11 N cm−1 for EtSNT, ESNT and ASNT, respectively. The force constants have been compared with those for several silicates and SiO bond length are predicted and discussed. |
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