Plasma Modeling and Prebiotic Chemistry: A Review of the State-of-the-Art and Perspectives.

Gaia Micca Longo,Luca Vialetto,Vincenzo Laporta,Paola Diomede,Savino Longo

doi:10.3390/molecules26123663

Abstract

We review the recent progress in the modeling of plasmas or ionized gases, with compositions compatible with that of primordial atmospheres. The plasma kinetics involves elementary processes by which free electrons ultimately activate weakly reactive molecules, such as carbon dioxide or methane, thereby potentially starting prebiotic reaction chains. These processes include electron–molecule reactions and energy exchanges between molecules. They are basic processes, for example, in the famous Miller-Urey experiment, and become relevant in any prebiotic scenario where the primordial atmosphere is significantly ionized by electrical activity, photoionization or meteor phenomena. The kinetics of plasma displays remarkable complexity due to the non-equilibrium features of the energy distributions involved. In particular, we argue that two concepts developed by the plasma modeling community, the electron velocity distribution function and the vibrational distribution function, may unlock much new information and provide insight into prebiotic processes initiated by electron–molecule collisions.

Highlights

IntroductionPublisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations
It has been shown that the methods used in the plasma modeling community reveal crucial aspects of the chemical processes that have never been taken into account in previous studies of prebiotic processes
Thereby, we propose to apply the theoretical methodologies that have been developed for the study of ionized gases to the Miller-Urey experience

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. It can be stated that the Miller-Urey experiment is the first abiotic synthesis of organic compounds, under simulated primordial Earth conditions, in the context of the studies on the origin of life. Under the hypotheses that the primordial Earth’s atmosphere consisted predominantly of CO and CO2 , the chemical channels previously considered for a reducing atmosphere (based on the preliminary production of the highly reactive HCN molecule) must be reformulated and subjected to new studies, bearing in mind that other components, even minority ones, can play a role in subsequent chemical reactions.

CO organic molecules

Tools from Plasma Kinetics

Kinetics of Molecular Activation by Plasma Electrons

Quantum Calculations for Elementary Processes

Conclusions and Perspectives