Electron nuclear dynamics, research

Although the theory of photodissociation has not yet reached the level of sophistication of experiment, major advances have been made in recent years by many research groups. This concerns the calculation of accurate multi-dimensional potential energy surfaces for excited electronic states and the dynamical treatment of the nuclear motion on these surfaces. The exact quantum mechanical modelling of the dissociation of a triatomic molecule is nowadays practicable without severe technical problems. Moreover, simple but nevertheless realistic models have been developed and compared against exact calculations which are very useful for understanding the interrelation between the potential and the nuclear dynamics on one hand and the experimental observables on the other hand. 

There are a number of intricate issues associated with conical intersections, concerning both the electronic structure, the nuclear dynamics, and the interaction of the molecule with the radiation field. Few of us are familiar with all these aspects of the problem, which have been analyzed in research papers scattered throughout the chemical physics literature. It is the intention of the present book to make this knowledge available to interested graduate students and researchers in the thriving field of femto-chemistry. 

Using the OPENCORE spectrometer, a research group led by M. Kitagawa in Osaka have developed an experimental setup for dynamic nuclear polarization (DNP) using electron spins in the photo-excited triplet state. This nuclear hyperpolarization technique, called hereafter triplet DNP,... 

In the introduction to Volume 1 of this series, the founding editors, J. N. Pitts, G. S. Hammond and W. A. Noyes, Jr. noted developments in a brief span of prior years that were important for progress in photochemistry flash photolysis, nuclear magnetic resonance, and electron spin resonance. A quarter of a century later, in Volume 14 (1988), the editors noted that since then two developments had been of prime significance the emergence of the laser from an esoteric possibility to an important light source, and the evolution of computers to microcomputers in common laboratory use of data acquisition. These developments strongly influenced research on the dynamic behavior of the excited state and other transients. 

The first topic has an important role in the interpretation and calculation of atomic and molecular structures and properties. It is needless to stress the importance of electronic correlation effects, a central topic of research in quantum chemistry. The relativistic formulations are of great importance not only from a formal viewpoint, but also for the increasing number of studies on atoms with high Z values in molecules and materials. Valence theory deserves special attention since it improves the electronic description of molecular systems and reactions with the point of view used by most laboratory chemists. Nuclear motion constitutes a broad research field of great importance to account for the internal molecular dynamics and spectroscopic properties. 

The authors aim to provide an up-to-date report on the state of the field. Our main scientific activity involves structural and dynamic studies of paramagnetic metalloproteins, in a Research center at the University of Florence. The laboratory is a NMR Research Infrastructure resource supported by the European Union to perform a European service. We are thus exposed to the needs of the scientific community, and have responded to them in several ways, from the development of new instruments or part of them to the description of new phenomena and development of new software. Since 1985, together with colleagues from the Universities of Pisa and Siena, we have organized nine Chianti Workshops on Electron and Nuclear Relaxation, a series of conferences well known to the scientific community in the field. 

An approach briefly presented here is based on a combination of the eikonal (or short wavelength) approximation for nuclei, and time-dependent Hartree-Fock states for the many-electron system, in what we have called the Eikonal/ TDHF approach.[13] A similar description can be obtained with narrow wavepackets for the nuclear motions. Several other approaches have recently been proposed for doing first principles dynamics, a very active area of current research. [39, 11, 15]... 

These limitations of sensitivity and contrast have led researchers to develop hyperpolarization methods, where the nuclear polarization is greatly increased by the manipulation of spin states. Currently, the most general and popular hyperpolarization method is dynamic nuclear polarization (DNP), where the much higher polarization of an unpaired electron is transferred to the nuclei of interest. DNP was originally... 

This review article is concerned with the structure, bonding, and dynamic processes of water molecules in crystalline solid hydrates. The most important experimental techniques in this field are structural analyses by both X-ray and neutron diffraction as well as infrared and Raman spectroscopic measurements. However, nuclear magnetic resonance, inelastic and quasi elastic neutron scattering, and certain less frequently used techniques, such as nuclear quadrupole resonance, electron paramagnetic resonance, and conductivity and permittivity measurements, are also relevant to solid hydrate research. 

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