Supercooling and freezing processes in nanoconfined water by time-resolved optical Kerr effect spectroscopy.
J Phys Condens Matter
; 27(19): 194107, 2015 May 20.
Article
en En
| MEDLINE
| ID: mdl-25924077
ABSTRACT
Using heterodyne-detected optical Kerr effect (HD-OKE) measurements, we investigate the vibrational dynamics and the structural relaxation of water nanoconfined in Vycor porous silica samples (pore size ≃ 4 nm) at different levels of hydration and temperatures. At low levels of hydration corresponding to two complete superficial water layers, no freezing occurs and the water remains mobile at all the investigated temperatures with dynamic features similar, but not equal to, the bulk water. The fully hydrated sample shows the formation of ice at about 248 K. This process does not involve all the contained water; a part of it remains in a supercooled phase. The structural relaxation times measured from the decay of the time-dependent HD-OKE signal shows the temperature dependence largely affected by the hydration level; the low frequency (ν < 500 cm(-1)) vibrational spectra obtained by the Fourier transforms of the HD-OKE signal appear less affected by confinement.
Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Agua
/
Nanopartículas
/
Nanoporos
/
Congelación
/
Hielo
/
Modelos Químicos
Idioma:
En
Revista:
J Phys Condens Matter
Asunto de la revista:
BIOFISICA
Año:
2015
Tipo del documento:
Article
País de afiliación:
Italia