Raman spectroscopic evidence of low temperature stability of D,L-glycolic and L-(+)-lactic acid crystals

Mohaček Grošev, Vlasta; Šoštarić, Vladimir; Maksimović, Aleksandar (2015) Raman spectroscopic evidence of low temperature stability of D,L-glycolic and L-(+)-lactic acid crystals. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 140 . pp. 35-43. ISSN 1386-1425

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Abstract

Raman and infrared spectra of polycrystalline D,L-glycolic and L-(+) lactic acid are presented and assigned both by an ab initio calculation of normal modes of free conformers and by self-consistent-charge density-functional-theory computational program DFTB+. Temperature dependent Raman spectra from 295 K to 10 K reveal great stability of crystal lattices since no soft modes and no band splittings that could be attributed to changes of the number of molecules per unit cell are observed. A semiempirical calculation with GULP program was used to estimate the strength of hydrogen bonds in crystals: in glycolic acid they have energies of -0.337 eV/mol, -0.329 eV/mol, -0.262 eV/mol and -0,242 eV/mol, while in lactic acid two hydrogen bonds have energies of -0.283 eV/mol and -0.202 eV/mol.

Item Type:	Article
Uncontrolled Keywords:	glycolic acid; lactic acid; Raman; infrared; DFTB+; GULP; normal modes; phonons; temperature stability; biodegradable material
Subjects:	NATURAL SCIENCES NATURAL SCIENCES > Physics > Atomic and Molecular Physics NATURAL SCIENCES > Physics > Condensed Matter Physics NATURAL SCIENCES > Chemistry > Physical Chemistry
Divisions:	Division of Materials Physics
Depositing User:	Vlasta Mohaček Grošev
Date Deposited:	09 Jan 2015 16:24
URI:	http://fulir.irb.hr/id/eprint/1646
DOI:	10.1016/j.saa.2014.12.048

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