Fig. 5: Transient vibrational nano-spectroscopy of FAMACs perovskite.
From: Ultrafast infrared nano-imaging of far-from-equilibrium carrier and vibrational dynamics
a Ground-state IR s-SNOM \({{{{{{{\rm{Re}}}}}}}}[{E}_{{{{{{{{\rm{NF}}}}}}}}}]\) imaging (top) and AFM topography (bottom). b HPP IR s-SNOM interferogram ΔINF(t) acquired at T = 2 ps with instantaneous polaron absorption and long-lived transient vibrational coherence. c Phase- and frequency-resolved nano-localized pump-probe \({{\Delta }}{E}_{{{{{{{{\rm{NF}}}}}}}}}(\overline{\nu })\) and ground-state response \({E}_{{{{{{{{\rm{NF}}}}}}}}}(\overline{\nu })\). d Decomposition of \({{{{{{{\rm{Im}}}}}}}}[{{\Delta }}{E}_{{{{{{{{\rm{NF}}}}}}}}}(\overline{\nu })]\) into the transient vibrational (\({{{{{{{\rm{Im}}}}}}}}[{{\Delta }}{E}_{{{{{{{{\rm{NF,vib}}}}}}}}}(\overline{\nu })]\)) and carrier (\({{{{{{{\rm{Im}}}}}}}}[{{\Delta }}{E}_{{{{{{{{\rm{NF,car}}}}}}}}}(\overline{\nu })]\)) contributions with a minor feature from Fano-type interference. e The nano-localized transient vibrational signal \({{{{{{{\rm{Im}}}}}}}}[{{\Delta }}{E}_{{{{{{{{\rm{NF,vib}}}}}}}}}(\overline{\nu })]\) at different sample locations shows nanoscale spatial heterogeneity in the polaron–cation coupling.
