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Dr. James R. Lyons

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Senior Scientist

Currently resides in AZ
jlyons [at] psi.edu
Areas of Expertise

Research Interests

My research interests are in the areas of planetary atmospheres, cosmochemistry, the Sun, and astrobiology, with the occasional diversion into exoplanets and compact fluorescent light bulbs. The core theme is how the stable isotopes of C, N, O and S can inform us about processes in these objects. For CFL bulbs, Hg isotopes are the crux. For exoplanets, I prefer condensate aerosols, which provide an isotopic respite. A key process for many of these objects is isotope effects in photodissociation. For the solar nebula, I've modeled isotope fractionation of O and N isotopes due to CO and N2 photodissociation, and what this implies for the distribution of these isotopes in the solar system. For planetary atmospheres, I've explored photochemical effects on S isotopes (ancient Earth) and O isotopes (modern Earth and Mars). For the Sun, I've revisited old measurements of C isotopes in the photosphere, with the goal of obtaining information about the Sun complementary to what Genesis has been able to provide thus far from collected solar wind samples. And what about my claims to Astrobiology? Here, my interests are still photon driven, and concern the generation of enantiomeric excesses in chiral molecules due to interaction with a circularly polarized UV radiation field. Isotopes are indirectly involved, but now as a constraint on the intensity of the UV radiation. 

Professional History

After completing PhD work at Caltech on atmospheric photochemistry of the outer solar system, I did a postdoc in Exobiology at UCSD in which I designed and carried an experiment to measure binding by 15-mer racemic peptides to a transition state analog to p-nitrophenyl acetate hydrolysis. It didn't work. More precisely, the histidine residues provided some catalysis, but not beyond what was expected. I returned to planetary atmospheres as a research scientist at UCLA, developing a strong focus on O and S isotope modeling for Earth atmosphere and the solar nebula. This blossomed into experimental spectroscopic work at the Soleil synchrotron in France. In 2013 I moved from UCLA to a research faculty position at ASU. I continued my work on O and S isotopes, developing a new direction for S isotope research for ancient Earth. I also added N isotopes to the mix for the solar nebula. In 2022 I moved to PSI to continue these research projects, and to explore new connections with colleagues here.

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