Theory of nonradiative decay with two or more electrons at play

Descripción del proyecto

Mapeo del movimiento de dos electrones

Cuando las moléculas absorben radiaciones de alta energía, expulsan electrones. Este proceso desencadena reacciones químicas en la atmósfera y en el interior de las células humanas. A veces, la radiación libera dos electrones a la vez o los excita juntos. Los métodos computacionales cuánticos actuales tienen dificultades para describir estos fenómenos. Como la mayoría de los métodos existentes solo rastrean electrones individuales o átomos simples, los cambios moleculares complejos siguen siendo un misterio. El equipo del proyecto UNBOUND TWO, financiado por el Consejo Europeo de Investigación, aborda esta laguna construyendo nuevos métodos de química cuántica para describir cómo dos electrones libres se mueven en sincronía. La atención se centra en los «estados doblemente excitados», que provocan reacciones químicas poco frecuentes. Su objetivo es ayudar a los científicos a interpretar los datos de experimentos avanzados. Los hallazgos mejorarán nuestros conocimientos sobre cómo la radiación modifica el mundo que nos rodea.

Objetivo

UNBOUND TWO aims to develop the quantum chemistry methods that are needed to interpret next-generation spectroscopy involving two or more unbound electrons and to understand chemical reactions involving unbound doubly-excited states.

Emerging spectroscopies can probe correlations between two electrons, which is fundamentally impossible with techniques that probe only one electron. To gain information about electronic and molecular structure from such spectra, theoretical modeling is key. However, existing methods are able to deal with only one emitted electron or they are geared toward atoms. As a result, the full potential of spectroscopy is not yet realized for molecules.

Electron attachment accompanied by electronic excitation can mediate unique chemical reactions that attachment to the ground state does not support, for example the cleavage of OH bonds. Theoretical modeling is essential to harness such reactions, but existing methods struggle with the pivotal unbound doubly-excited states so that electron-induced chemistry is still at an early stage.

Building on recent breakthroughs for nonradiative decay in which only one electron becomes unbound, we will investigate processes in which two or more electrons are at play, for example in Auger and Coster-Kronig cascades and in dissociative electron attachment and dissociative recombination. To achieve these goals, we will advance the quantum chemistry of unbound electrons substantially. We will develop methods that treat singly-excited and doubly-excited states evenhandedly and describe the correlated motion of two emitted electrons. In computational applications, we will study the interaction of organic molecules and transition-metal compounds in gas phase and solution with ionizing radiation and free electrons over an energy range from <0.1 to >1000 eV.