Analysis and Control of Ultrafast Photoinduced Reactions
The present monograph summarizes, in a comprehensive way, several years of joint experimental and theoretical frontier research on ultrafast laser-induced molecular dynamics and its control. Emphasis is set on the characterization of the nuclear dyn
- PDF / 391,649 Bytes
- 23 Pages / 439.455 x 666.283 pts Page_size
- 100 Downloads / 265 Views
On dynamics Remarkable progress has been made in the elucidation of ultrafast dynamics and its control driven by femtosecond laser pulses in small molecules, large-scale molecular systems, clusters, nanostructures, surfaces, condensed phase and biomolecules. The exploration of photoinduced ultrafast response, dynamics, reactivity and function in ubiquitous molecular, nanoscale, macroscopic and biological systems pertains to the interrogation and control of the phenomena of energy acquisition, storage and disposal, as explored from the microscopic point of view. Photoinduced ultrafast processes in chemistry, physics, material science, nanoscience, and biology constitute a broad, interdisciplinary, novel and fascinating research area, blending theoretical concepts and experimental techniques in a wide range of scientific disciplines. The foundations for the analysis and control of ultrafast photoinduced processes were laid during the last eighty years with the development of nonradiative dynamics from small molecules to biomolecules [1–6], while during the last twenty years remarkable progress was made with the advent of femtosecond dynamics and control at the temporal resolution of nuclear motion [1, 7–12]. This scientific historical development can be artistically described by ascending the ‘magic mountain’ of molecular, cluster, condensed phase and biological dynamics by several paths (Fig. 1.1), all of which go heavenwards toward a unified and complete description of structure-electronic level structurespectroscopy-dynamics-function relations and correlations. The genesis of intramolecular nonradiative dynamics dates back to the origins of quantum mechanics, when the 1926 groundbreaking work of Schr¨ odinger and Heisenberg laid the foundations for the description of time-dependent phenomena in the quantum world. In 1928 Bonhoeffer and Farkas [13] observed that predissociation in the electronically excited ammonia molecule, which involves the decay of a metastable state to a dissociative continuum, hν
1/τ
i.e., NH3 → NH∗3 → NH2 +H, is manifested by spectral line broadening, with
2
J. Jortner
Fig. 1.1. An artist’s view of the ‘magic mountain’ of the evolution of dynamics. The names of some of the pioneers who initiated each scientific area are marked on the paths.
a spectral linewidth Γ that considerably exceeds the radiative linewidth. This seminal work established the first spectroscopic-dynamic relation, providing experimental verification of the Heisenberg energy-time uncertainty relation, and pioneering the field of intramolecular dynamics. At about the same time, Wenzel [14] worked on another facet of nonradiative dynamics for the theory of atomic autoionization, establishing the basic unified theory of nonradiative processes. For a metastable (predissociating or autoionizing) state into a (dissociative or ionization) continuum, the decay lifetime τ was quantified in terms of the Golden Rule τ −1 = (2π/)|V |2 (dn/dE), where V is the matrix element of the Hamiltonian inducing the nonradiative transition, and dn/
Data Loading...
