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Author Junaid, Bushiri M. ♦ Nayar, V. U.
Source CUSAT-Thesis
Content type Text
Publisher ELSEVIER
File Format PDF
Language English
Subject Domain (in DDC) Natural sciences & mathematics ♦ Chemistry & allied sciences ♦ Technology
Subject Keyword Raman spectra ♦ IR spectra ♦ Phase transitions
Abstract Raman and FTIR spectra of [Cu(H2O)6](BrO3)2 and [Al(H2O)6](BrO3)3 · 3H2O are recorded and analyzed. Theobserved bands are assigned on the basis of BrO3− and H2O vibrations. Additional bands obtained in the region of 3 and 1 modes in [Cu(H2O)6](BrO3)2 are due to the lifting of degeneracy of 3 modes, since the BrO3− ion occupiesa site of lower symmetry. The appearance 1 mode of BrO3− anion at a lower wavenumber (771 cm−1) is attributedto the attachment of hydrogen to the BrO3− anion. The presence of three inequivalent bromate groups in the[Al(H2O)6](BrO3)3 · 3H2O structure is confirmed. The lifting of degeneracy of 4 mode indicates that the symmetry ofBrO3− anion is lowered in the above crystal from C3v to C1. The appearance of additional bands in the stretching andbonding mode regions of water indicates the presence of hydrogen bonds of different strengths in both the crystals.Temperature dependent Raman spectra of single crystal [Cu(H2O)6](BrO3)2 are recorded in the range 77–523 K forvarious temperatures. A small structural rearrangement takes place in BrO3− ion in the crystal at 391 K. Hydrogenbounds in the crystal are rearranging themselves leading to the loss of one water molecule at 485 K. This is precededby the reorientation of BrO3− ions causing a phase transition at 447 K. Changes in intensities and wavenumbers ofthe bands and the narrowing down of the bands at 77 K are attributed to the settling down of protons into orderedpositions in the crystal
Education Level UG and PG
Learning Resource Type Article