Advances in Hydrogen Molecular Ions: H3+, H5+ and beyond

Jonathan Tennyson gained a BA in Natural Sciences from King's College, Cambridge in 1977 and a PhD in Theoretical Chemistry from the University of Sussex in 1980. He spent a productive two years as Royal Society Western European Exchange Fellow at the University of Nijmegen in the Netherlands, In 1982 he joined the Theory Group at Daresbury Laboratory. He was appointed a “New Blood” lecturer at University College London in Theoretical Atomic Physics in 1985. He became Professor of Physics in 1994; was Head of Department in 2004-11 and became Massey Professor of Physics in 2005. He was elected an FRS in 2009.

His research interests cover a range of topics on the theory of small molecules. In particular I compute spectra of these molecules (such as water) and collide electrons (and occasionally positrons) with them. He is interested in the astrophysical, atmospheric and other consequences of these processes. He recently started a new project, ExoMol (www.exomol.com), aimed at calculating comprehensive line lists for models exoplanets and other hot atmosphere.

Dr Prosmiti has more than 20 years of experience in Physics/Chemistry (Molecular, Quantum and Computational) research. Her interests are broad, constantly adapted to international advances, and focus on the study of structural, spectroscopic, dynamic and transport properties of molecular systems from the gas to condensed phases. Along her career, she has implemented and/or developed methods to treat ionic hydrogen clusters, van der Waals complexes, doped helium aggregates, and nanoconfined molecules in clathrate hydrates and fullerenes to study their formation, spectroscopy, predissociation and photofragmentation, and more recently she carried out computational simulations on aqueous solutions, with interest in weak interactions, for studying solvation/hydration effects. Dr Prosmiti's research work has been funded by the European Union, the Greek Ministry of Education, the Engineering and Physical Sciences Research Council (UK), the Community of Madrid and the Ministry of Education and Science of Spain. She has written more than 125 articles in scientific journals of international prestige (see at Google Scholar), and participated in more than 150 international conferences.

Mats Larsson is professor of physics at the Department of Physics, Stockholm University, and also director of the AlbaNova University Center, a joint enterprise between Stockholm University and the Royal Institute of Technology. He is member of the Royal Swedish Academy of Sciences and its physics class, which the awarding institution for the Nobel Prizes in Physics and Chemistry. He has a long affiliation with H₃⁺ and wrote the first proposal for an experiment with H₃⁺ in the storage ring CRYRING exactly 20 years ago. Needless to say, the situation concerning the recombination of H₃⁺ was also at that time in complete turmoil.

Dr Christiane Helling is Reader in the School of Physics & Astronomy at the University of St Andrews and Director of the St Andrews Centre for Exoplanet Science. She was educated in Berlin, Germany, and previously worked for the European Space Agency. With support from the European Research Council, she established the LEAP (Life Electricity Atmospheres Planets) research group, following her interests in understanding atmospheres of extrasolar planets, the physics and chemistry of cloud formation and lightning, as well as their possible roles for the emergence of life. The headline of the Centre for Exoplanet Science, which combines expertise from astronomy/astrophysics, geosciences, biology, philosophy and social anthropology, summarises a key driver of her scientific endeavour: “Understanding how unusual Earth is may help humanity to appreciate how special it is.”

Xavier Urbain is a Senior Research Fellow of the FRS-FNRS and a professor at the Université catholique de Louvain, where he teaches atomic physics at the bachelor and master level.

Trained as both an experimental and a theoretical physicist, Xavier focuses his research on collisional and radiative processes at play in astrophysical and technical plasmas, with special emphasis on the reactivity of small ionic systems. He specialized in merged and crossed beam experiments involving electrons, atoms and ions, and is active in several laboratories (UCLouvain, Columbia University, MPI for Nuclear Physics). He also conducts experiments with ultrafast lasers by bringing equipment to laser facilities (CEA Saclay, CELIA Bordeaux).

Xavier has pioneered several methods allowing absolute determination of cross sections for collision- or photon-induced processes, and various approaches to multiple fragment detection. Differential measurements obtained by high resolution momentum imaging provide additional insight into the dynamics, which regularly challenge common views.

Dr Geballe obtained a PhD in physics in 1974 under Professor Charles Townes at U C Berkeley. Following postdoctoral fellowships at Berkeley and Leiden, and a Carnegie Fellowship at Hale Observatories in Pasadena, he became a staff astronomer at the United Kingdom Infrared Telescope in 1981. He was Astronomer-in-charge, Associate Director, and Head of Operations at UKIRT from 1987 until 1998, when he joined Gemini. Among his research interests are the Galactic center, the late stages of stellar evolution, H₃⁺ as a probe of interstellar gas, the composition of interstellar dust, the surfaces, atmospheres, and aurorae of solar system objects, and brown dwarfs.

Oka received his BS degree in Chemistry from the University of Tokyo in 1955 and a PhD for his work on microwave spectroscopy on formaldehyde in Professor Shimoda's lab in Physics of the same University in 1960. He was then a postdoctoral fellow at the National Research Council of Canada, later Herzberg Institute of Astrophysics. He joined the University of Chicago in 1981 jointly affiliated to the Department of Chemistry and the Department of Astronomy and Astrophysics. He joined the Enrico Fermi Institute in 1993. He became a professor emeritus in 2003. His research interests are in the areas of high-resolution spectroscopy and astrophysics of molecular ions, in particular, H₃⁺ near the Galactic centre.

Paola Caselli studied Astronomy at the University of Bologna, where she graduated in 1990. In 1994 she obtained the PhD in Astrophysics at the University of Bologna, after spending nine months as visiting student at the Ohio State University with Professor Eric Herbst and two years at the Harvard Smithsonian Center for Astrophysics (CfA) as a pre-doctoral fellow with Professor Phil Myers. After a Postdoctoral Fellowship at CfA, in 1996 she became Researcher at the Arcetri Astrophysical Observatory in Florence, where she remained until 2005. In 2006 and 2007 she was Visiting Scholar in the Department of Astronomy, Harvard University, and in 2007 she became Professor of Astronomy at the School of Physics and Astronomy, University of Leeds. Since 2014, she is Director of the Centre for Astrochemical Studies at the Max-Planck-Institute for Extraterrestrial Physics and Honorary Professor at the Ludwig Maximilian University of Munich.

Cecilia Ceccarelli is an Astronomer at the Institute de Planétologie et Astrophysique de Grenoble (IPAG) of the Université Grenoble Alpes (UGA), in France. She started her career with a thesis on the Cosmic Background Radiation at the Università La Sapienza di Roma (Italy) in 1982. In 1987, she joined the Italian CNR and worked on Star Formation. In 2000, she moved to France, where she joined IPAG and worked on Astrochemistry. Since then, her main research focus is the chemistry of young systems that will eventually form Solar-like planetary systems. She co-authored more than 260 articles in peer-reviewed international journals and led several large international projects.

In 2006, she received the prize Irène Joliot-Curie Femme Scientifique de l'année, awarded by the French Ministère délègue à l'Enseignement Supérieur et à la Recherche. In 2017, she was awarded the European Research Council (ERC) project Dawn of Organic Chemistry.

Pierre Drossart has devoted his research activity to planetology, in the field of the atmosphere of giant and terrestrial planets through infrared spectroscopy. From ground-based infrared spectroscopy on CFHT/FTS instrument, he has obtained many results on the spectroscopy of Jupiter, including the first spectroscopic detection of H3+ on Jupiter. He has participated in many planetary space missions for infrared imaging spectrometer (Galileo/NIMS, IKS/Phobos, Cassini/VIMS, OMEGA/Mars Express, VIRTIS/Venus Express, VIRTIS/Rosetta). He is currently involved in the future ARIEL mission of European Space Agency (ESA) in the infrared spectrometer devoted to exoplanets' transit spectroscopy.

He has been head of department at LESIA (Laboratoire d'Études Spatiales et d'Instrumentation en Astrophysique) in France from 2010 to 2018.

Tom Stallard spent the first decade of his scientific career within the Physics department of University College London, having already completed an undergraduate degree in Planetary Science within the Geology department of the same university. During this time he worked under Professor Steve Miller, and together they make the first measurements of the ion winds within the upper atmospheres of Gas Giants. Tom expanded upon these investigations to include a long-term, currently ongoing, series of observations of Saturn's ion winds, using the NASA InfraRed Telescope Facility, in support of the Cassini mission. In 2007, Tom won an RCUK Academic Fellowship at the University of Leicester. Around this time, the Cassini VIMS instrument founded the British-based VIMS-MAG collaboration team, of which Tom became the lead researcher. In his work at Leicester and through this Cassini collaboration, he has been involved in the production of significant findings from both the Cassini mission itself, from the associated ground-based observations, as well as a number of independent studies of the upper atmospheres of the Gas Giants.

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Licia Ray is a lecturer in Physics at Lancaster University. She is an expert in the coupling between planetary atmospheres and their surrounding plasma environments. Her research focuses on developing numerical models of the characteristics of the auroral acceleration region in centrifugally driven systems, auroral current systems, and the feedback between the thermosphere, ionosphere and magnetosphere. Licia is also interested in observations of auroral emissions and is a co-I on an XMM-Newton campaign to observe Jupiter, coincident with the Juno mission. She has given over 20 invited talks and seminars on MI Coupling at the Outer Planets since earning her PhD from the University of Colorado at Boulder in 2010.

Dr Henrik Melin is an expert in analysing ground-based and spacecraft observations of the giant planets. He obtained his PhD in planetary science from University College London in 2006, working with Professor Steve Miller on ground-based infrared observations of H3+ from Jupiter, Saturn, and Uranus. Henrik spent his first postdoc in Los Angles, working on ultraviolet data from the Cassini spacecraft, mapping neutrals inside the magnetosphere of the planet. Returning to the UK in 2009, he settled in at the University of Leicester, working to combine spacecraft and ground-based observations of the giant planets, studying the entire column of atmosphere, from the troposphere, through the stratosphere and up to the thermosphere.

Dr Laura McKemmish is an Australian quantum chemist and molecular physicist. From 2016 to 2017, Dr McKemmish was a Marie Sklodowska-Curie research fellow at University College London, where she developed novel theoretical computational methodologies to treat scattering of ultracold atoms and diatomic species such as H+ + H2. In January 2018, Laura started her new position as Lecturer in School of Chemistry at University of New South Wales in Australia. Here, she is working with fantastic keen students to continue her career goals of developing innovative theoretical and computational techniques and applying these to cutting-edge problems across the sciences.

After a study of physics in Wuppertal and Göttingen Professor Schlemmer prepared a Diploma thesis (1986) and a PhD thesis (1991) in the group of Professor J P Toennies at the Max-Planck-Institute for fluid dynamics in Göttingen working on the evaporation of water from a thin liquid jet and on inelastic and reactive collisions in a crossed beam experiment. As a post-doc (1992-1994) at the University of California at Berkeley, USA, in the group of Professor R J Saykally he searched for the origin of the interstellar unidentified infrared bands (UIR) using an IR emission spectrometer. From 1994-2003 he worked in the group of Professor D Gerlich (University of Technology Chemnitz) on the trapping of ions and nanoparticles. After his habilitation he worked as an assistant professor at the University of Technology Chemnitz. During this time they developed the methods of nanoparticle mass determination and light induced reactions as a technique of ion spectroscopy. In 2003 and 2004 he was appointed as an associate professor at Leiden observatory heading the group of laboratory astrophysics. Since 2004 he has been professor for experimental physics at Cologne University. The work of his group focusses on spectroscopy of molecules in the THz and IR regime. In addition they are interested in understanding molecular collisions in various interstellar environments ranging from the cold universe, where eg isotopic enrichment prevails to circumstellar envelops where refractory species are produced at much higher temperatures.

Alexander Alijah received his PhD in Chemistry from the University of Bielefeld (Germany) in 1988 with a theoretical thesis on Photoionisation of hydrogen atoms in a strong magnetic field. From 1988 to 1990 he was a postdoc at the Department of Physics and Applied Physics of the University of Strathclyde (UK). He then returned to Bielefeld, where he worked as a lecturer from 1990 to 2000. In 1996 he completed his Habilitation with a thesis on Dynamics and spectra of triatomic molecules with strong coupling between rotation, vibration and electronic motions. From 2000 to 2009 he was a researcher at the University of Coimbra (Portugal), and in 2009 professor at the Physics Department of the Federal University of Minas Gerais (Brazil). Since 2009, he is full professor of theoretical chemistry at the University of Reims (France). His main research interests are theoretical chemistry and theoretical spectroscopy of small molecules. H3+ is one of his favourite molecules.

Holger Kreckel earned his doctoral degree in 2003 with a thesis on "Internal Excitations of Stored Triatomic Hydrogen Ions" at the Max Planck Institute for Nuclear Physics (MPIK) in Heidelberg. During this time he worked at the heavy ion Test Storage Ring (TSR), employing a variety of experimental techniques to shed light on the internal cooling and electron recombination of small molecular ions. After two PostDocs in the United States, his interests started to focus on the formation and destruction of interstellar molecules. For this topic he was awarded a starting grant of the European Research Council in 2012, and he returned as an independent research group leader to MPIK in order to work with the novel Cryogenic Storage Ring (CSR). Other recent research interests include the chemistry of the early universe, photodetachement studies of negative ions, spectroscopy in ion traps, and Coulomb explosion imaging of chiral molecules.