title: Relaxation dynamics of deeply supercooled confined water in L,L-diphenylalanine micro/nanotubes.
abstract: The temperature dependence (10-290 K) of the low-frequency (20-150 cm(-1)) Raman-active phonon modes of deeply supercooled confined water in L,L-diphenylalanine micro/nanotubes was analyzed. The isolated dynamics of a specific geometry of a water cluster (pentamer) in a supercooled confined regime was studied in detail. A fragile-to-strong transition at 204 K was observed and related to the crossing of the Widom line. Analysis of peptide vibrational modes coupled to water hydrogen bonds indicated that hydrogen bond fluctuations play an irrelevant role in this system. Our results are in agreement with the second critical point of water existence hypothesis.
authors.affiliation: Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Av. dos Estados 5001, Santo André-SP, 09210-580, Brazil. herculano.martinho@ufabc.edu.br.
authors.forename: P M G L
authors.initials: PM
authors.lastname: Ferreira
authors.forename: M S
authors.initials: MS
authors.lastname: Ishikawa
authors.forename: S
authors.initials: S
authors.lastname: Kogikoski
authors.forename: W A
authors.initials: WA
authors.lastname: Alves
authors.forename: H
authors.initials: H
authors.lastname: Martinho
mesh_terms: D004151:Dipeptides; D043942:Nanotubes; D010649:Phenylalanine / Q000031:analogs & derivatives* / Q000737:chemistry; D013059:Spectrum Analysis, Raman; D013696:Temperature; D014867:Water / Q000737:chemistry*
chemical_list: D004151:Dipeptides; D014867:Water; C026650:phenylalanylphenylalanine; D010649:Phenylalanine