Infra-red imaging of bulk water and water–solid interfaces under stable and metastable conditions

Phys. Chem. Chem. Phys.

Simon

et al. 2016

Self Cite

Water-solid interactions at the macroscopic level (beyond tens of nanometers) are often viewed as the coexistence of two bulk phases with a sharp interface in many areas spanning from biology to (geo)chemistry and various technological fields (membranes, microfluidics, coatings, etc.). Here we present experimental evidence indicating that such a view may be a significant oversimplification. High-resolution infrared and Raman experiments were performed in a 60 × 20 μm(2) quartz cavity, synthetically created and initially filled with demineralized water. The IR mapping (3 × 3 μm(2) beam size) performed using the SOLEIL synchrotron radiation source displays two important features: (i) the presence of a dangling free-OH component, a signature of hydrophobic inner walls; (ii) a shift of the OH-stretching band which essentially makes the 3200 cm(-1) sub-band predominate over the usual main component at around 3400 cm(-1). Raman maps confirmed these signatures (though less marked than IR's) and afforded a refined spatial distribution of this interfacial signal. This spatial resolution, statistically treated, results in a puzzling image of a 1-3 μm thick marked-liquid layer along the entire liquid-solid interface. The common view is then challenged by this strong evidence that a μm-thick layer analogous to an interphase forms at the solid-liquid interface. The thermodynamic counterpart of the vibrational shifts amounts to around +1 kJ mol(-1) at the interface with a rapidly decreasing signature towards the cavity centre, meaning that vicinal water may form a reactive layer, of micrometer thickness, expected to have an elevated melting point, a depressed boiling temperature, and enhanced solvent properties.

Section: Detailed Analysis Of the Oh Stretching Bandsupporting

confidence: 92%

Section: Decomposition Of the Oh Stretching Bandmentioning

confidence: 99%

Section: Interfacial Thermodynamicsmentioning

confidence: 99%

See 1 more Smart Citation

Oversolubility in the microvicinity of solid–solution interfaces

Bergonzi

Phys. Chem. Chem. Phys.

Simon

et al. 2016

Self Cite

“…To account for the various environments of a molecule, the OH stretching band is frequently decomposed into three Gaussian components 16,18,20,31,[37][38][39][40] , each embodying a certain connectivity of the corresponding water molecules, the whole featuring the liquid in the experimental time and space. Hence, each Gaussian sub-band describes the quantity and the energy of the water molecules with a given mean coordination number (Fig.…”

Section: Decomposition Of the Stretching Bandmentioning

confidence: 99%

Gibbs free energy of liquid water derived from infrared measurements

Bergonzi

Phys. Chem. Chem. Phys.

Brubach

et al. 2014

Self Cite

Infrared spectra of pure liquid water were recorded from 20 cm(-1) to 4000 cm(-1) at temperatures ranging from 263 K to 363 K. The evolution of connectivity, libration, bending and OH stretching bands as a function of temperature follows the evolution of the inter-molecular dynamics, and so gives insight into the internal energy averaged over the measurement time and space. A partition function, which takes into account the inter-molecular and intra-molecular modes of vibration of water, all variable with the molecular networking, was developed to convert this vibrational absorption behavior of water into its macroscopic Gibbs free energy, assuming the vibrational energy to feature most of the water energy. Calculated Gibbs free energies along the thermal range are in close agreement with the literature values up to 318 K. Above this temperature, contributions specific to the non H-bonded molecules must be involved to closely fit the thermodynamics of water. We discussed this temperature threshold in relation to the well-known isosbestic point. Generally speaking, our approach is valuable to convert the IR molecular data into mean field properties, a quantitative basis to predict how water behaves in natural or industrial settings.

“…About the second issue, the general feeling is toward admitting the continuity of behavior from stability to metastability, meaning that superheated water is no more than a "particular" state of otherwise-bulk liquid (e.g. [10][11][12][13]), but, here again, some doubts still need to be lifted. A current experiment tries to quantify the internal stress in fluid inclusions, by recording direct signals of the pressure change directly inside the inclusion, shunting any use of EoS.…”

Section: Superheating Limits and Lifetime 31 Measurements And Interpmentioning

confidence: 99%

Experimental Superheating and Cavitation of Water and Solutions at Spinodal-Like Negative Pressures

Transport and Reactivity of Solutions in Confined Hydrosystems

Shmulovich

2013

Self Cite

The superheated liquids are metastable with respect to their vapour, what means they can exist under arid conditions whatever the temperature: capillary liquid extracted from arid soils (desert shrubs, Mars sub-surface, …), solutions in the deep Earth crust, or water involved in rapid disequilibrium events (terrestrial or submarine geysers). The superheating state changes the solvent properties of liquids, and so modifies phase transitions (solid-liquid, liquidvapor) P-T-X conditions. The synthetic fluid inclusion (SFI) enables to fabricate micro-volumes of handmade liquid dispersed inside quartz, which readily superheat. Volumes of SFI are intermediate between macro-systems, in which superheating is restricted to around-30-35 MPa with very short lifetime, and nanosystems, wherein confinement effects predominate and in which the host size is similar to the one of the critical nucleus of vapour phase (huge nucleation barrier). This volume-to-metastability relationship is still to be defined quantitatively, and we are targeting to combine thermometric classical measurements with spectrometric characterizations, enabling to establish the threshold between micro-and nano-systems precisely. Meanwhile, the experiments performed so far illustrate the diversity of contexts and situations that could be impacted by superheating issues.