Photoexcited superfluid He nanodroplets - a versatile playground for atto- and femto-second dynamics
Prof Sivarama Krishnan
Indian Institute of Technology Madras, Chennai, India
[email protected]
Correlated and collective electron dynamics has been the bedrock of photoexcited meso- and nano-scale quantum aggregates - atomic and molecular clusters. A wide range of rich physical processes defined by quantum electron dynamics on femto- and atto-second timescales natural to the electrons and nuclei. However, the complexity of processes and computational effort required to simulate them motivates us to seek and build controlled ensembles from the angstrom to the nanoscale which can be investigated by experiments to build up our understanding. Nanoscale clusters of He, or He nanodroplets, containing anywhere from a few atoms to several million per cluster, provide a facile route to this realization. These clusters formed in supersonic jets are superfluid and can easily be doped with any atomic or molecular dopants. Photoexciting these with extreme ultraviolet (EUV) or soft xray (SXR) photon pulses or intense optical pulses induces electron dynamics marked by correlated and collective processes, respectively. Prominent among these are the interatomic Coulombic decay (ICD) process and rapidly evolving nanoplasmas in these nanodroplets: the ensuing quantum electron dynamics evolve on femto- and atto-second timescales. These are probed using table-top as well as accelerator-based photon sources. We will present representative works that capture the rich physics involved, including our own contributions. These motivate further experimental exploration of these systems using modern state-of-the-art attosecond light sources based on both high-harmonic generation as well as free-electron lasers.
[1] L B Ltaief et al., Physical Review Letters 131 (2), 023001 (2023)
[2] S R Krishnan et al., Physical Chemistry Chemical Physics 16 (19), 8721-8730 (2014)
[3] S R Krishnan et al., Physical review letters 107 (17), 173402 (2011).
Indian Institute of Technology Madras, Chennai, India
[email protected]
Correlated and collective electron dynamics has been the bedrock of photoexcited meso- and nano-scale quantum aggregates - atomic and molecular clusters. A wide range of rich physical processes defined by quantum electron dynamics on femto- and atto-second timescales natural to the electrons and nuclei. However, the complexity of processes and computational effort required to simulate them motivates us to seek and build controlled ensembles from the angstrom to the nanoscale which can be investigated by experiments to build up our understanding. Nanoscale clusters of He, or He nanodroplets, containing anywhere from a few atoms to several million per cluster, provide a facile route to this realization. These clusters formed in supersonic jets are superfluid and can easily be doped with any atomic or molecular dopants. Photoexciting these with extreme ultraviolet (EUV) or soft xray (SXR) photon pulses or intense optical pulses induces electron dynamics marked by correlated and collective processes, respectively. Prominent among these are the interatomic Coulombic decay (ICD) process and rapidly evolving nanoplasmas in these nanodroplets: the ensuing quantum electron dynamics evolve on femto- and atto-second timescales. These are probed using table-top as well as accelerator-based photon sources. We will present representative works that capture the rich physics involved, including our own contributions. These motivate further experimental exploration of these systems using modern state-of-the-art attosecond light sources based on both high-harmonic generation as well as free-electron lasers.
[1] L B Ltaief et al., Physical Review Letters 131 (2), 023001 (2023)
[2] S R Krishnan et al., Physical Chemistry Chemical Physics 16 (19), 8721-8730 (2014)
[3] S R Krishnan et al., Physical review letters 107 (17), 173402 (2011).
