Photon- and Electron-Driven Atomic Collision Processes: General Theory and Accurate Numerical Calculations

Drake University, Des Moines IA

Investigators

Abstract

This project deals with the interaction of light (mostly lasers) and charged particles (mostly electrons) with atoms and ions. The results are of importance for the understanding of fundamental collision dynamics, and they also fulfill the urgent practical need for accurate atomic data to model the physics of stars, plasmas, lasers, and planetary atmospheres. The short-pulse intense-laser part of the project requires accurate solutions of the time-dependent Schroedinger equation on a numerical space-time grid. With the rapid advances currently seen in computational resources, such studies can now be conducted for realistic, as opposed to idealized, model systems. This work is important to facilitate further developments in the imaging and control of submicroscopic reactions, which in turn are expected to have broad impact by reaching out from physics to chemistry and ultimately biology. Another topic is quantum entanglement created in electron-atom collisions. This area has potential for applications in quantum information technology. Many experimental efforts worldwide are supported through the present project, which will also train a post-doctoral associate and a number of research students. Most of the numerical calculations will be based upon the non-perturbative R-matrix (close-coupling) method using a highly flexible B-spline implementation with non-orthogonal orbital sets, as well as direct solutions of the time-dependent Schroedinger equation using various grid-based approaches and basis-function expansions. For single and double ionization of complex atoms by intense atto/femto-second laser pulses, the methods will be combined in such a way that individual parts of the "big problem" can be treated in highly efficient and optimized ways. One example is the use of time-independent multi-electron Coulomb and dipole matrix elements from the B-spline R-matrix method in a propagation scheme for the solution of the time-dependent Schroedinger equation in a few-cycle laser pulse. This general strategy will be extended to the treatment of double ionization involving inner shells. Much emphasis will be placed on the testing of numerical methods and the visualization of the results, both of which are ideal for student involvement. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.