Calculation of electric quadrupole linestrengths for diatomic molecules: Application to the H2, CO, HF, and O2 molecules

Journal of Chemical Physics | December 2021

Electric quadrupole transitions are crucial for describing the spectra of many homonuclear molecules, including O2, this paper presents a new computational methodology for calculating highly accurate absorption strengths and Einstein coefficients for rotational, vibrational and electronic quadrupole transitions in diatomic molecules.

ExoMol line lists - XLIV. infrared and ultraviolet line list for silicon monoxide (28Si16O)

MNRAS | November 2021

Silicon monoxide is believed to be present in the atmospheres of hot rocky planets, orbiting close to their host star. Here extreme temperatures cause silicate compounds on the planet's surface to vapourize, leading to the accumulation of significant quantities of SiO in the planet's atmosphere. Observation of SiO in exoplanet retrievals requires accurate molecular opacities for the molecule across a range of wavelengths. This ExoMol line list aims to provide such data to facilitate the detection of SiO in the atmosphere of hot rocky exoplanets.

Clouds spoil UK's view of Saturn and Jupiter's 'great conjunction'

The Guardian | January 2021

This was a short interview I gave to the Guardian newspaper on the closest night of Saturn and Jupiter's historic conjunction.

The 2020 release of the ExoMol database

J. Quant. Spectrosc. Rad. Transf. | November 2020

The ExoMol database provides molecular data for studies of planetary and exoplanetary atmospheres, as well as a wide range of other research and industrial applications.

The core of the database comes from the ExoMol project which primarily uses theoretical methods, albeit usually fine-tuned to reproduce laboratory spectra, to generate very extensive line lists for studies of hot bodies. A major push in the new release is towards accurate characterisation of transition frequencies for use in high resolution studies of exoplanets and other bodies.

A High-Resolution Linelist for Molecular Oxygen

Europlanet Science Congress | September 2020

Molecular oxygen (O2) is of particular interest in exoplanetary observations not least of all as an important biosignature on habitable planets. In this work we develop and apply ab initio computational techniques to produce an accurate electric quadrupole spectrum of molecular oxygen presented for use in atmospheric retrievals across a range of temperatures, and made available through the ExoMol database.

Higher Order Transition Moments in the Spectra of Diatomic Molecules

ESA ARIEL SMC2020 | January 2020

The ARIEL space telescope is the European Space Agency's M4 mission in the ESA Cosmic Vision longterm plan. The launch is planned in 2029 by the Ariane 62 launch vehicle for a nominal four year mission to observe and characterise exoplanetary atmospheres.

We consider contributions from higher order transition moments. Principally the electric quadrupole and magnetic dipole moments - responsible for the infrared spectrum of many diatomic molecules - and also the electric polarisability, which generates Raman spectra.