Chemical Transformations in the Inter-Stellar Medium: Photochemical Processes

Introduction

Until the beginning of the last century, the scientific convention was that the material in the interstellar medium (ISM) between stars and galaxies was mostly in atomic and ionic form – thus the formation of complex molecules was improbable. Today, however, large complex molecules are being discovered at a dazzling rate – demonstrating the molecular nature of our universe.

Unique Conditions in the ISM

The physical conditions in the ISM are extremely different than on Earth. In addition to extreme temperatures and low density, there are radiation fields which, when interacting with atoms and molecules, result in unique chemistry occurring in excited electronic states. This interaction is responsible for many of the chemical phenomena observed in the ISM.

Current Knowledge and Challenges

Currently, very little is known about the formation mechanisms of molecules in the ISM. The efforts to uncover the chemistry of the ISM are multidisciplinary, yielding experimental, observational, and theoretical results.

Importance of Theoretical Results

Theoretical results are crucial for obtaining a molecular-level understanding of chemical phenomena. They help to guide and decipher experimental and observational results. However, up to now, the toolkit of modern quantum chemistry cannot model the dynamics of large molecules in a highly excited electronic state.

Proposed Study

The aim of this proposed study is to fill this gap. I will develop new theoretical capabilities within quantum chemistry, specifically ensemble density functional theory, that will enable us to model the dynamics of highly excited large molecules such as polyaromatic hydrocarbons, which play a crucial role in the chemical evolution of the ISM.

Impact on Computational Chemistry

The ability to accurately model the dynamics of excited states will significantly advance the field of computational chemistry. It will provide the capability to model systems that are currently outside its reach and offer a leap in our current understanding of the chemistry of the ISM.