Nanoparticles catalyze exotic molecular processes in intense laser fields: real implications in the Earth’s atmosphere

Re-entry of satellites into the earth’s atmosphere leads to formation of metallic nanoparticles which can act as catalysts for unusual molecular reactions. Results will be presented of an international experimental study I was involved in to explore formation of gaseous H3+ ions from water molecules condensed on SiO2 nanoparticles (100-300 nm size) upon irradiation by intense laser light. The experiments, using reaction nanoscopy to unambiguously identify the reactions products, were conducted at the American University of Sharjah, with participation of colleagues from the University of Jordan, Ludwig-Maximilians-Universität Munich, Max Planck Institute of Quantum Optics, Garching, and Manipal Academy of Higher Education. Our results {Nature Commun. 12, 3839 (2021)} show that nanoparticles not only act as a catalyst in forming H3+ cations from water, they also lead to dramatic enhancement of their momenta and energy. This is likely to be caused by near-field effects which give rise to localized field (intensity) enhancement. Conditions in our terrestrial laboratory might be replicated by nature; dust in the inner heliosphere, and in planetary debris discs around other stars include nanometer-sized dust particles. Might these dust nanoparticles act as catalysts for the formation of H3+ ions? Or of other molecular species requiring similar conditions, if these nanoparticles are impacted by cosmic rays of charged particles or solar wind highly charged ions?

About Speaker:
Deepak Mathur joined the Institute in October 1981 as a Visiting Fellow, with a mandate to initiate an experimental programme in atomic and molecular physics. He retired in April 2017 as Distinguished Professor and J.C. Bose National Fellow. The research programmes that he and his colleagues pursued encompassed atomic and molecular dynamics, the physics of low-energy electronic and ionic collisions, ultrafast laser science and several facets of biological physics. He is a Fellow of INSA, the Indian Academy of Sciences and the World Academy of Science. He was awarded the Bhatnagar Prize, the European Union’s Erasmus Mundus Fellowship at Imperial College London, the Royal Society Guest Fellowship at the University of Oxford; he is a Gold Medallist of the International Society of Ultrafast Intense Laser Science. He has been co-Editor of Europhysics Letters, and editor board member of Rapid Communications in Mass Spectrometry, Pramana, and the Indian Journal of Pure and Applied Physics; he has published several monographs.