"We survey the dynamics of the interfacial water at the air/water interface. We reveal that the ultrafast vibrational energy transfer dynamics and spectral diffusion of the OH stretch mode at the interface differs from those in the bulk significantly; the rotational motion is 3 times faster than in the bulk and energy relaxation is dominated by the rotational dynamics as well as the vibrational energy transfer from the free OH group to the H-bonded OH groups of a water molecule with the free OH group. These insights can only be obtained by conducting the time-resolved surface-specific spectroscopic studies presented in this thesis."--Samenvatting auteur.

This thesis presents a highly innovative study of the ultrafast structural and vibrational dynamics of hydrated phospholipids, the basic constituents of cell membranes. As a novel approach to the water-phospholipid interface, the author studies phosphate vibrations using the most advanced methods of nonlinear vibrational spectroscopy, including femtosecond two-dimensional infrared spectroscopy. He shows for the first time that the structure of interfacial water undergoes very limited fluctuations on a 300 fs time scale and that the lifetimes of hydrogen bonds with the phospholipid are typically longer than 10 ps. Such properties originate from the steric hindrance of water fluctuations at the interface and the orienting action of strong electric fields from the phospholipid head group dipoles. In an extensive series of additional experiments, the vibrational lifetimes of the different vibrations and the processes of energy dissipation are elucidated in detail.

No doubt, water is the most important liquid on the planet. In addition to the obligatory need for water in life, water is widely used in diverse applications. In most applications if not all, water is interfaced with different materials, at different phases depending on the application. This unique value of water originates from its chemical structure, which is based on hydrogen bonding. Although these chemical bonding in bulk liquid and vapor water have extensively been investigated, in interfacial water are not yet fully understood. This thesis presents an investigation of ultrafast vibrational dynamics of hydrogen bonding in interfacial water. In a first chapter, the experimental technique and tools needed for the study of interfacial vibrational dynamics are exposed. In the first part of a second chapter, vibrational coherence dynamics of free OH stretch modes at the alumina/water interface are investigated. And in the second part, vibrational coherence dynamics of hydrogen bonded OH stretch modes at the calcium fluoride/water interface are investigated. To understand the dynamics of vibrational energy flow within an interfacial network of hydrogen bonding, the investigation of vibrational coupling dynamics at the calcium fluoride/water interface takes place in a third chapter. Unlike what has already been reported in this topic, in our work, the vibrational energy will be initially deposited at the second vibrational excited state, through an overtone transition.

This thesis highlights the study into the structures and dynamics of interfacial water, which is a cutting edge issue in condensed matter physics. Using the first principles calculation, classical molecular dynamics simulation and the simulation of atomic force microscopy (AFM), combined with the experimental results of AFM, the book systematically studies interfacial water at the atomic scale, especially the structure and growth mechanism of two-dimensional ice on hydrophobic Au (111) surface, the structure and the interconversion of the Eigen/Zundel hydrated proton on the Au(111) and Pt(111) surfaces, the microstructure and the hydration effect of the diffusion of ion hydrates on NaCl surface. This book displays the atomic scale information about the interaction between water and surface, and achieves many innovative results. Furthermore, the research methods included in this book can be further extended to study the more complex interfacial systems.

This book focuses on the study of the interfacial water using molecular dynamics simulation and experimental sum frequency generation spectroscopy. It proposes a new definition of the free O-H groups at water-air interface and presents research on the structure and dynamics of these groups. Furthermore, it discusses the exponential decay nature of the orientation distribution of the free O-H groups of interfacial water and ascribes the origin of the down pointing free O-H groups to the presence of capillary waves on the surface. It also describes how, based on this new definition, a maximum surface H-bond density of around 200 K at ice surface was found, as the maximum results from two competing effects. Lastly, the book discusses the absorption of water molecules at the water–TiO2 interface. Providing insights into the combination of molecular dynamics simulation and experimental sum frequency generation spectroscopy, it is a valuable resource for researchers in the field.

Water dynamics near interfaces and in confined systems, as manifested by vibrational relaxation, orientational relaxation, and spectral diffusion of the water hydroxyl stretch (5% HOD in H2O), are measured via infrared (IR) pump-probe and 2D IR vibrational echo techniques. It is shown that a two component model for population and orientational relaxation accurately describes the dynamics for systems comprised of two types of hydrogen bonding ensembles: waters that are hydrogen bonded to other waters and waters at an interfacial region. Through a combination of spectroscopic and data analysis techniques, the dynamics of these two environments become separable. This two component model is successfully applied to binary mixtures of water and tetraethylene glycol dimethyl ether. The effects of confinement on water dynamics are studied by examining water inside of reverse micelles made with the surfactant Aerosol-OT (AOT), which contains charged head groups. Large reverse micelles (diameter [greater than or equal to] 4.6 nm) can be decomposed into two separate environments: a bulk water core and an interfacial water shell. Each region has distinct dynamics that can be resolved experimentally using the two component model. The core follows bulk water dynamics while interfacial water shows slower dynamics that are independent of size for large reverse micelles. To explore how the chemical composition of the interface influences dynamics, the dynamics of water in AOT reverse micelles are compared to water dynamics in reverse micelles made from the neutral surfactant Igepal CO-520. It is found that the presence of an interface plays the major role in determining interfacial water dynamics and not the chemical composition. A two component model is also developed for spectral diffusion. The two component model for spectral diffusion is an extended version of the center line slope (CLS) analysis procedure, originally developed for single ensemble systems. The modified two component CLS procedure allows the CLS behavior of water at the interface to be back-calculated from known parameters. From the interfacial CLS, the interfacial frequency-frequency correlation function, which describes spectral diffusion, can be determined. It is found that, similar to orientational relaxation behavior in large AOT reverse micelles, the interfacial FFCF does not vary with increasing reverse micelle size.

This thesis presents a highly innovative study of the ultrafast structural and vibrational dynamics of hydrated phospholipids, the basic constituents of cell membranes. As a novel approach to the water-phospholipid interface, the author studies phosphate vibrations using the most advanced methods of nonlinear vibrational spectroscopy, including femtosecond two-dimensional infrared spectroscopy. He shows for the first time that the structure of interfacial water undergoes very limited fluctuations on a 300 fs time scale and that the lifetimes of hydrogen bonds with the phospholipid are typically longer than 10 ps. Such properties originate from the steric hindrance of water fluctuations at the interface and the orienting action of strong electric fields from the phospholipid head group dipoles. In an extensive series of additional experiments, the vibrational lifetimes of the different vibrations and the processes of energy dissipation are elucidated in detail.