Micro-transitions or breathers in L-alanine?
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Micro-transitions or breathers in L-alanine? / Barthes, M.; Bordallo, H. N.; Dénoyer, F.; Lorenzo, J. E.; Zaccaro, J.; Robert, A.; Zontone, F.
In: European Physical Journal B, Vol. 37, No. 3, 01.02.2004, p. 375-382.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - Micro-transitions or breathers in L-alanine?
AU - Barthes, M.
AU - Bordallo, H. N.
AU - Dénoyer, F.
AU - Lorenzo, J. E.
AU - Zaccaro, J.
AU - Robert, A.
AU - Zontone, F.
PY - 2004/2/1
Y1 - 2004/2/1
N2 - The lattice dynamics of crystalline L-alanine shows unusual features tentatively assigned to a localization of vibrational energy. However, other properties alternatively suggest the existence of a second order phase transition undetected in previous crystallographic work. In this paper, we present the results of a high resolution X-ray diffraction study down to 10 K, together with new structure determinations at intermediate temperatures. The data rule out the hypothesis of a conventional structural phase transition. No change in the space group symmetry is observed and an anomalous decrease of the lattice parameter c in discrete steps is discovered when heating the crystal from 10 K to room temperature. It could be ascribed to a progressive conformational change of the NH3 + group of the zwitterionic molecule. An analysis of the physical properties of crystalline L-alanine suggests the existence of a strong dynamic Jahn-Teller-like effect owing to the NH3 + charge-lattice coupling. This would explain both the splitting of some vibrational states and properties related to a microscopic lattice instability like the onset of depolarization in the transmitted light below ∼250 K.
AB - The lattice dynamics of crystalline L-alanine shows unusual features tentatively assigned to a localization of vibrational energy. However, other properties alternatively suggest the existence of a second order phase transition undetected in previous crystallographic work. In this paper, we present the results of a high resolution X-ray diffraction study down to 10 K, together with new structure determinations at intermediate temperatures. The data rule out the hypothesis of a conventional structural phase transition. No change in the space group symmetry is observed and an anomalous decrease of the lattice parameter c in discrete steps is discovered when heating the crystal from 10 K to room temperature. It could be ascribed to a progressive conformational change of the NH3 + group of the zwitterionic molecule. An analysis of the physical properties of crystalline L-alanine suggests the existence of a strong dynamic Jahn-Teller-like effect owing to the NH3 + charge-lattice coupling. This would explain both the splitting of some vibrational states and properties related to a microscopic lattice instability like the onset of depolarization in the transmitted light below ∼250 K.
UR - http://www.scopus.com/inward/record.url?scp=2542445179&partnerID=8YFLogxK
U2 - 10.1140/epjb/e2004-00069-1
DO - 10.1140/epjb/e2004-00069-1
M3 - Journal article
AN - SCOPUS:2542445179
VL - 37
SP - 375
EP - 382
JO - European Physical Journal B. Condensed Matter and Complex Systems
JF - European Physical Journal B. Condensed Matter and Complex Systems
SN - 1434-6028
IS - 3
ER -
ID: 210117788