Theoretical Femtosecond Physics

This volume offers theoretical investigations of atoms and molecules interacting with pulsed or continuous wave lasers. Theoretical background is included, and the text incorporates several exercises. Additional calculations are performed in the appendices.

This textbook extends from the basics of femtosecond physics all the way to some of the latest developments in the field. In this updated edition, the chapter on laser-driven atoms is augmented by the discussion of two-electron atoms interacting with strong and short laser pulses, as well as by a review of ATI rings and low energy structures in photo-electron spectra. In the chapter on laser-driven molecules a discussion of 2D infrared spectroscopy is incorporated. Theoretical investigations of atoms and molecules interacting with pulsed lasers up to atomic field strengths on the order of 10^16 W/cm2 are leading to an understanding of many challenging experimental discoveries. The presentation starts with a brief introduction to pulsed laser physics. The basis for the non-perturbative treatment of laser-matter interaction in the book is the time-dependent Schrödinger equation. Its analytical as well as numerical solution are laid out in some detail. The light field is treated classically and different possible gauges for the field-matter interaction are discussed. Physical phenomena, ranging from paradigmatic Rabi-oscillations in two-level systems to the ionization of atoms, the generation of high-order harmonics, the ionization and dissociation of molecules, as well as the control of chemical reactions are presented and discussed on a fundamental level. In this way, the theoretical background for state of the art experiments with strong and short laser pulses is given. The new text is augmented by several additional exercises and now contains a total of forty-eight problems, whose worked-out solutions are given in the last chapter. In addition, some detailed calculations are performed in the appendices. Furthermore, each chapter ends with references to more specialized literature.

Femtosecond physics is a novel branch of the theoretical physics, which investigates the interaction of atoms and molecules with pulsed or continuous wave lasers. In particular, this book treats the laser-matter coupling in a non-perturbative way using both approximate and numerical solutions of the Time-Dependent Schrödinger Equation (TDSE). Here, with the exception of one case study, the electromagnetic field is classically treated. Several physical phenomena ranging from ionization of atoms and molecules to their dissociation and the control of photochemical reactions are presented and discussed. This book begins with a wide Section 1, which deals with the TDSE and in particular, with its solutions. Initially, it considers only those cases exactly soluble, such as a class of potentials for which the TDSE with position-dependent mass allows reduction to a stationary Schrödinger equation, a time-dependent anharmonic oscillator, and at last, the derivation of a general form of the imaginary effective potential that relates the TDSE to the generalized Schrödinger equation with a memory kernel. Section 2 focuses on the field-matter interaction in quantum two-level systems, and in particular, a derivation of analytic broadband /2 and pulses that perform exact, or asymptotically exact, excitation of spin systems, presenting a nontrivial dynamic connection between nonlinear spin and linear spring systems. Finally, the last Section 3 considers several cases of atoms and molecules in strong laser fields. In detail, this section discusses a kinematic mechanism underlying the recently discovered 'near-zero energy structure' in the photoionization of atoms in strong mid-infrared laser fields and presents a number of benchmark calculations for intense short-pulse laser interactions with small atoms and molecules. Moreover, Section 3 presents a theoretical approach to investigate the high-order harmonic generation in the nano-graphene molecules and describes the few-electron ultrastrong light-matter coupling in a quantum LC circuit. Book jacket.

This is the first comprehensive treatment of the interaction of femtosecond laser pulses with solids at nonrelativistic intensity. It connects phenomena from the subtle atomic motion on the nanoscale to the generation of extreme pressure and temperature in the interaction zone confined inside a solid. The femtosecond laser-matter interaction has al

This book presents the latest developments in Femtosecond Chemistry and Physics for the study of ultrafast photo-induced molecular processes. Molecular systems, from the simplest H2 molecule to polymers or biological macromolecules, constitute central objects of interest for Physics, Chemistry and Biology, and despite the broad range of phenomena that they exhibit, they share some common behaviors. One of the most significant of those is that many of the processes involving chemical transformation (nuclear reorganization, bond breaking, bond making) take place in an extraordinarily short time, in or around the femtosecond temporal scale (1 fs = 10-15 s). A number of experimental approaches - very particularly the developments in the generation and manipulation of ultrashort laser pulses - coupled with theoretical progress, provide the ultrafast scientist with powerful tools to understand matter and its interaction with light, at this spatial and temporal scale. This book is an attempt to reunite some of the state-of-the-art research that is being carried out in the field of ultrafast molecular science, from theoretical developments, through new phenomena induced by intense laser fields, to the latest techniques applied to the study of molecular dynamics.

This book, the first of this kind, provides a comprehensive introduction to ultrafast phenomena, covering the fundamentals of ultrafast spin and charge dynamics, femtosecond magnetism, all-optical spin switching, and high-harmonic generation. It covers the experimental tools, including ultrafast pump-probe experiments, and theoretical methods including quantum chemistry and density functional theory, both time-independent and time-dependent. The authors explain in clear language how an ultrafast laser pulse is generated experimentally, how it can induce rapid responses in electrons and spins in molecules, nanostructures and solids (magnetic materials and superconductors), and how it can create high-harmonic generation from atoms and solids on the attosecond timescale. They also show how this field is driving the next generation of magnetic storage devices through femtomagnetism, all-optical spin switching in ferrimagnets and beyond, magnetic logic in magnetic molecules, and ultrafast intense light sources, incorporating numerous computer programs, examples, and problems throughout, to show how the beautiful research can be done behind the scene. Key features: · Provides a clear introduction to modern ultrafast phenomena and their applications in physics, chemistry, materials sciences, and engineering. · Presents in detail how high-harmonic generation occurs in atoms and solids. · Explains ultrafast demagnetization and spin switching, a new frontier for development of faster magnetic storage devices. · Includes numerous worked-out examples and problems in each chapter, with real research codes in density functional theory and quantum chemical calculations provided in the chapters and in the Appendices. This book is intended for undergraduate and graduate students, researchers in physics, chemistry, biology, materials sciences, and engineering.

This book presents the latest developments in Femtosecond Chemistry and Physics for the study of ultrafast photo-induced molecular processes. Molecular systems, from the simplest H2 molecule to polymers or biological macromolecules, constitute central objects of interest for Physics, Chemistry and Biology, and despite the broad range of phenomena that they exhibit, they share some common behaviors. One of the most significant of those is that many of the processes involving chemical transformation (nuclear reorganization, bond breaking, bond making) take place in an extraordinarily short time, in or around the femtosecond temporal scale (1 fs = 10-15 s). A number of experimental approaches - very particularly the developments in the generation and manipulation of ultrashort laser pulses - coupled with theoretical progress, provide the ultrafast scientist with powerful tools to understand matter and its interaction with light, at this spatial and temporal scale. This book is an attempt to reunite some of the state-of-the-art research that is being carried out in the field of ultrafast molecular science, from theoretical developments, through new phenomena induced by intense laser fields, to the latest techniques applied to the study of molecular dynamics.

This book presents a unified view of the response of materials as a result of femtosecond laser excitation, introducing a general theory that captures both ultrashort-time non-thermal and long-time thermal phenomena. It includes a novel method for performing ultra-large-scale molecular dynamics simulations extending into experimental and technological spatial dimensions with ab-initio precision. For this, it introduces a new class of interatomic potentials, constructed from ab-initio data with the help of a self-learning algorithm, and verified by direct comparison with experiments in two different materials — the semiconductor silicon and the semimetal antimony. In addition to a detailed description of the new concepts introduced, as well as giving a timely review of ultrafast phenomena, the book provides a rigorous introduction to the field of laser–matter interaction and ab-initio description of solids, delivering a complete and self-contained examination of the topic from the very first principles. It explains, step by step from the basic physical principles, the underlying concepts in quantum mechanics, solid-state physics, thermodynamics, statistical mechanics, and electrodynamics, introducing all necessary mathematical theorems as well as their proofs. A collection of appendices provide the reader with an appropriate review of many fundamental mathematical concepts, as well as important analytical and numerical parameters used in the simulations.