Conical Intersections

It is widely recognized nowadays that conical intersections of molecular potential-energy surfaces play a key mechanistic role in the spectroscopy of polyatomic molecules, photochemistry and chemical kinetics. This invaluable book presents a systematic exposition of the current state of knowledge about conical intersections, which has been elaborated in research papers scattered throughout the chemical physics literature. Section I of the book provides a comprehensive analysis of the electronic-structure aspects of conical intersections. Section II shows the importance of conical intersections in chemical reaction dynamics and gives an overview of the computational techniques employed to describe the dynamics at conical intersections. Finally, Section III deals with the role of conical intersections in the fields of molecular spectroscopy and laser control of chemical reaction dynamics. This book has been selected for coverage in: • CC / Physical, Chemical & Earth Sciences • Chemistry Citation Index(tm) • Index to Scientific Book Contents® (ISBC) Contents: Fundamental Concepts and Electronic Structure TheoryConical Intersections in Photoinduced and Collisional DynamicsDetection and Control of Chemical Dynamics at Conical Intersections Readership: Researchers in theoretical chemistry, molecular spectroscopy and photochemistry. Keywords:Conical Intersections;Photochemistry;Chemical Reaction Dynamics;Photo-dissociation;Diabetic

This invaluable book presents a systematic exposition of the current state of knowledge about conical intersections, which has been elaborated in research papers scattered throughout the chemical physics literature.

This concise book introduces and discusses the basic theory of conical intersections with applications in atomic, molecular and condensed matter physics. Conical intersections are linked to the energy of quantum systems. They can occur in any physical system characterized by both slow and fast degrees of freedom - such as e.g. the fast electrons and slow nuclei of a vibrating and rotating molecule - and are important when studying the evolution of quantum systems controlled by classical parameters. Furthermore, they play a relevant role for understanding the topological properties of condensed matter systems. Conical intersections are associated with many interesting features, such as a breakdown of the Born-Oppenheimer approximation and the appearance of nontrivial artificial gauge structures, similar to the Aharonov-Bohm effect. Some applications presented in this book include - Molecular Systems: some molecules in nonlinear nuclear configurations undergo Jahn-Teller distortions under which the molecule lower their symmetry if the electronic states belong to a degenerate irreducible representation of the molecular point group. - Solid State Physics: different types of Berry phases associated with conical intersections can be used to detect topologically nontrivial states of matter, such as topological insulators, Weyl semi-metals, as well as Majorana fermions in superconductors. - Cold Atoms: the motion of cold atoms in slowly varying inhomogeneous laser fields is governed by artificial gauge fields that arise when averaging over the fast internal degrees of freedom of the atoms. These gauge fields can be Abelian or non-Abelian, which opens up the possibility to create analogs to various relativistic effects at low speed.

The concept of adiabatic electronic potential-energy surfaces, defined by the Born?Oppenheimer approximation, is fundamental to our thinking about chemical processes. Recent computational as well as experimental studies have produced ample evidence that the so-called conical intersections of electronic energy surfaces, predicted by von Neumann and Wigner in 1929, are the rule rather than the exception in polyatomic molecules. It is nowadays increasingly recognized that conical intersections play a key mechanistic role in chemical reaction dynamics. This volume provides an up-to-date overview of the multi-faceted research on the role of conical intersections in photochemistry and photobiology, including basic theoretical concepts, novel computational strategies as well as innovative experiments. The contents and discussions will be of value to advanced students and researchers in photochemistry, molecular spectroscopy and related areas.

In this in-depth analysis, Peter Muir argues that Gordon Matta-Clark?s Conical Intersect (1975) is emblematic of Henri Lefebvre?s understanding of art?s function in relation to urban space. By engaging with Lefebvre?s theory in conjunction with the perspectives of other writers, such as Michel de Certeau, Jacques Derrida, and George Bataille, the book elicits a story that presents the artwork?s significance, origins and legacies. Conical Intersect is a multi-media artwork, which involves the intersections of architecture, sculpture, film, and photography, as well as being a three-dimensional model that reflects aspects of urban, art, and architectural theory, along with a number of cultural and historiographic discourses which are still present and active. This book navigates these many complex narratives by using the central ?hole? of Conical Intersect as its focal point: this apparently vacuous circle around which the events, documents, and other historical or theoretical references surrounding Matta-Clark?s project, are perpetually in circulation. Thus, Conical Intersect is imagined as an insatiable absence around which discourses continually form, dissipate and resolve. Muir argues that Conical Intersect is much more than an ?artistic hole.? Due to its location at Plateau Beaubourg in Paris, it is simultaneously an object of art and an instrument of social critique.

Pt. I. Fundamental aspects and electronic structure. 1. Conical intersections in organic photochemistry / M.A. Robb. 2. Efficient excited-state deactivation in organic chromophores and biologically relevant molecules: role of electron and proton transfer processes / A.L. Sobolewski and W. Domcke. 3. Three-state conical intersections / S. Matsika. 4. Spin-orbit vibronic coupling in Jahn-Teller systems / L.V. Poluyanov and W. Domcke. 5. Symmetry analysis of geometric-phase effects in quantum dynamics / S.C. Althorpe -- pt. II. Dynamics at conical intersections. 6. Conical intersections in electron photodetachment spectroscopy: theory and applications / M.S. Schuurman and D.R. Yarkony. 7. Multistate vibronic dynamics and multiple conical intersections / S. Faraji, S. Gomez-Carrasco and H. Koppel. 8. Conical intersections coupled to an environment / I. Burghardt [und weitere]. 9. Ab initio multiple spawning: first principles dynamics around conical intersections / S. Yang and T.J. Martinez. 10. Non-Born-Oppenheimer molecular dynamics for conical intersections, avoided crossings, and weak interactions / A.W. Jasper and D.G. Truhlar. 11. Computational and methodological elements for nonadiabatic trajectory dynamics simulations of molecules / M. Barbatti, R. Shepard and H. Lischka. 12. Nonadiabatic trajectory calculations with ab initio and semiempirical methods / E. Fabiano [und weitere]. 13. Multistate nonadiabatic dynamics "on the fly" in complex systems and its control by laser fields / R. Mitric, J. Petersen and V. Bonacic-Koutecky. 14. Laser control of ultrafast dynamics at conical intersections / Y. Ohtsuki and W. Domcke -- pt. III. Experimental detection of dynamics at conical intersections. 15. Exploring nuclear motion through conical intersections in the UV photodissociation of azoles, phenols and related systems / T.A.A. Oliver [und weitere]. 16. Interrogation of nonadiabatic molecular dynamics via time-resolved photoelectron spectroscopy / M.S. Schuurman and A. Stolow. 17. Pump-probe spectroscopy of ultrafast vibronic dynamics in organic chromophores / N.K. Schwalb [und weitere]. 18. Femtosecond pump-probe polarization spectroscopy of vibronic dynamics at conical intersections and funnels / W.K. Peters, E.R. Smith and D.M. Jonas

Comprehensive theoretical and experimental analysis of UV-radiation and low energy electron induced phenomena in nucleic acid bases (NABs) and base assemblies are presented in this book. NABs are highly photostable; the absorbed energy is dissipated in the form of ultrafast nonradiative decay. This book highlights the possible mechanisms of these phenomena which is important for all living species and discusses technical challenges in exploration of these processes.