Alexander Dalgarno and the development of astrochemistry

TL;DR

This article frames astrochemistry as an interdisciplinary field catalyzed by Alexander Dalgarno, whose theoretical work on atomic and molecular processes underpins the field’s foundations. It chronicles how technological advances and observational milestones—from 1960s radio and UV data to 2020s space missions—narrowed the gap between quantum mechanics and cosmic chemistry, while outlining Dalgarno's pivotal roles in theory development, education, and institutional building. The work highlights key themes such as H2 formation and spectroscopy, ion-molecule networks, PDR modeling, and the influence of cosmic rays, as well as the extension of astrochemistry into planetary atmospheres and shocks. Together, these elements illustrate how Dalgarno’s career helped shape a self-sustaining, globally connected scientific community and established methodological pillars still central to contemporary astrochemistry.

Abstract

The interdisciplinary field of astrochemistry arose during the 1970s as observations in previously unexplored parts of the electromagnetic spectrum began to reveal the extent of a molecular component of interstellar matter with a surprisingly rich chemistry. Astrochemistry expanded further in order to explain the role of atomic and molecular processes in a broad range of phenomena in the universe. It is instructive to describe the current scope of astrochemistry using the career and accomplishments of Alexander Dalgarno as an organizing principle. Dalgarno helped to establish a self-sustaining community of astrochemists around the world. His own research interests highlight the early development of astrochemistry and anticipate much of its later evolution. His theoretical investigations of fundamental atomic and molecular processes lie at the heart of the subject.