Evidence of polaron excitations in low temperature Raman spectra of oxalic acid dihydrate (CROSBI ID 227043)
Prilog u časopisu | izvorni znanstveni rad | međunarodna recenzija
Podaci o odgovornosti
Mohaček Grošev, Vlasta ; Grdadolnik, Jože ; Hadži, Dušan
engleski
Evidence of polaron excitations in low temperature Raman spectra of oxalic acid dihydrate
Low temperature Raman spectra of oxalic acid dihydrate (8K - 300 K) both for polycrystalline and single crystal phase show strong variation with temperature in the interval from 1200 to 2000 cm-1. Previous low temperature diffraction studies all confirmed the stability of the crystal P21/n phase with no indications of any phase transition, reporting the existence of a strong hydrogen bond between the oxalic acid and a water molecule. A new group of Raman bands in the 1200 – 1300 cm-1 interval below 90 K is observed, caused by possible loss of the centre of inversion. This in turn could originate either due to disorder in hydroxyl proton positions, or due to proton transfer from carboxylic group to water molecule. The hypothesis of proton transfer is further supported by the emergence of new bands centered at 1600 cm-1 and 1813 cm-1, which can be explained with vibrations of H3O+ ions. The broad band at 1600 cm-1 looses intensity, while the band at 1813 cm-1 gains intensity on cooling. The agreement between quantum calculations of vibrational spectra and experimentally observed Raman bands of hydronium ions in oxalic acid sesquihydrate crystal corroborate this hypothesis.
polaron ; Raman ; oxalic acid dihydrate ; hydrogen bond ; lattice dynamics ; lattice defects ; CRYSTAL09
nije evidentirano
nije evidentirano
nije evidentirano
nije evidentirano
nije evidentirano
nije evidentirano
Podaci o izdanju
120 (18)
2016.
2789-2796
objavljeno
1089-5639
10.1021/acs.jpca.5b12577