Correlation between macroscopic and microscopic relaxation dynamics of water: Evidence for two liquid forms.

Water is vital for life, and without it, biomolecules and cells cannot maintain their structures and functions. The remarkable properties of water originate from its ability to form hydrogen-bonding networks and dynamics, which the connectivity constantly alters because of the orientation rotation of individual water molecules. Experimental investigation of the dynamics of water, however, has proven challenging due to the strong absorption of water at terahertz frequencies.

Interfacial layers between ion and water detected by terahertz spectroscopy.

Dynamic fluctuations in the hydrogen-bond network of water occur from femto- to nanosecond timescales and provide insight into the structural/dynamical aspects of water at ion-water interfaces. Employing terahertz spectroscopy assisted with molecular dynamics simulations, we study aqueous chloride solutions of five monovalent cations, namely, Li, Na, K, Rb, and Cs. We show that ions modify the behavior of the surrounding water molecules and form interfacial layers of water around them with physical properties distinct from those of bulk water.

Probing Adaptation of Hydration and Protein Dynamics to Temperature.

Protein dynamics is strongly influenced by the surrounding environment and physiological conditions. Here we employ broadband megahertz-to-terahertz spectroscopy to explore the dynamics of water and myoglobin protein on an extended time scale from femto- to nanosecond. The dielectric spectra reveal several relaxations corresponding to the orientational polarization mechanism, including the dynamics of loosely bound, tightly bound, and bulk water, as well as collective vibrational modes of protein in an aqueous environment.

Gold-black manufacture, microstructure, and optical characterization.

A previous contribution formulates a first-principle dipole antenna theory for predicting the polarization-sensitive directional spectral absorptance of gold-black in the near infrared. The current contribution chronicles a successful effort to validate that theory. After a brief review of gold-black history, we describe in some detail the design and construction of a vapor-deposition cell for laying down gold-black coatings on a mirrorlike gold substrate.