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Ultrafast infrared nano-spectroscopic imaging of heterogeneous photoinduced dynamical processes

ORAL

Abstract

Low-energy responses and interactions at mid-infrared frequencies often play central roles in photoinduced dynamical phenomena, ranging from phase transitions in quantum materials to polaron formations in photovoltaic materials. However, the spatial heterogeneities and temporal evolution associated with such low-energy processes in the photoinduced transient state has remained elusive. Here, we develop and apply ultrafast infrared scattering scanning near-field optical microscopy (IR s-SNOM) to characterize photoinduced dynamics with far-from-equilibrium excitation and ultrahigh spatio-temporal-spectral resolution. For unambiguous determination of nano-scale phase and spectral responses, we develop optical pump - infrared probe nano-imaging with heterodyne detection. We demonstrate the performance of ultrafast IR s-SNOM to probe transient quantum states of the photoinduced heterogeneous metallic phase in vanadium oxide microrods, as well as spatially varying polaron-molecule coupling in lead halide perovskite films. The approach of ultrafast heterodyne IR s-SNOM with strong pump excitation is generally applicable to a wide range of strong transient field phenomena, providing for fundamental insight into heterogeneous electronic, structural, and dynamical properties of materials.

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Presenters

  • Jun Nishida

    Department of Physics, Department of Chemistry and JILA, University of Colorado, Boulder

Authors

  • Jun Nishida

    Department of Physics, Department of Chemistry and JILA, University of Colorado, Boulder

  • Samuel C. Johnson

    Department of Physics, Department of Chemistry and JILA, University of Colorado, Boulder

  • Sven A. Doenges

    Department of Physics, Department of Chemistry and JILA, University of Colorado, Boulder, Department of Physics, Department of Chemistry, and JILA, University of Colorado, Boulder

  • Amani H Alfaifi

    Univ of Denver, National Renewable Energy Laboratory

  • Sean Shaheen

    Department of Electrical, Computer, and Energy Engineering, University of Colorado Boulder, Electrical, Computer and Energy Engineering, University of Colorado Boulder, Renewable and Sustainable Energy Institute, University of Colorado, Boulder

  • Markus B. Raschke

    University of Colorado, Boulder, Physics and Chemistry, University of Colorado, Boulder, University of Colorado Boulder, Department of Physics, Department of Chemistry, and JILA, University of Colorado - Boulder, Department of Physics, Department of Chemistry and JILA, University of Colorado, Boulder, Department of Physics, Department of Chemistry, and JILA, University of Colorado, Boulder, Physics, University of Colorado, Boulder, Physics, Chemistry, and JILA, University of Colorado, Boulder