Polarized components of Raman spectra of O–H vibrations in liquid water

Electrically induced liquid-liquid phase transition in water at room temperature

In this work we expand on findings previously reported [Wexler et al., Phys. Chem. Chem. Phys., 2016, 18, 16281] on the experimental observation of a phase transition in a hydrogen bonded liquid manifesting in long range dipole-dipole interactions. The studied system, liquid water stressed by an electric field, exhibits collective oscillations brought about through spontaneous breakdown of symmetry. Raman spectroscopy identifies the primary excitation of the emergent phase as transverse optically active phonon-like sidebands that appear on the hydrogen bonded asymmetric stretch mode. The phase transition is observed throughout the entire volume of liquid. The system also exhibits a self-similarity relation between the scattered Raman intensity and the electric field strength which further supports the conclusion that collective behavior persists against thermal disruption. The experimental findings are discussed in terms of a quantum field theory for macroscopic quantum systems.

The cellular environment of cancerous human tissue. Interfacial and dangling water as a "hydration fingerprint"

Despite a large number of publications, the role of water in the cellular environment of biological tissue has not been clarified. Characterizing the biological interface is a key challenge in understanding the interactions of water in the tissue. Although we often assume that the properties of the bulk water can be translated to the crowded biological environment, this approach must be considerably revised when considering the biological interface. To our knowledge, few studies have directly monitored the interactions and accumulation of water in the restricted environments of the biological tissue upon realistic crowding conditions. The present study focuses on a molecular picture of water molecules at the biological interface, or specifically, water molecules adjacent to the hydrophobic and hydrophilic surfaces of normal and cancerous tissues. We recorded and analyzed the IR and Raman spectra of the νs(OH) stretching modes of water at the biological interfaces of the human breast and neck tissues. The results revealed dramatic changes in the water content in the tissue and are potentially relevant to both the fundamental problems of interfacial water modeling and the molecular diagnostics of cancer as a 'hydration fingerprint'. Herein, we will discuss the origin of the vibrational substructures observed for the νs(OH) stretching modes of water, showing that the interfacial water interacting via H-bond with other water molecules and biomolecules at the biological surface and free OH vibration of the dangling water are sensitive indicators of the pathology between the normal (noncancerous) and cancerous tissue and cancer types.

Accurate measurements of the Raman scattering coefficient and the depolarization ratio in liquid water

Despite a long history, the Raman scattering coefficient of water has so far only been measured with 10% uncertainty using a 95% confidence interval. In this paper, we present an experiment where we have achieved 1.5% uncertainty by using a low concentration of Rhodamine 6G in ethanol as a reference along with accurate consideration of polarization-related effects and the geometry of the experimental setup. We have found that the photon-to-photon Raman scattering coefficient of the OH stretching band of liquid water is (1.84±0.03)×10(-4) m(-1) when integrated over the spectral frequency range from 620 to 700 nm while the exciting laser operates at 532 nm. We have also accurately measured the depolarization ratio across this band.