Sunday, September 10, 2017

Abstract-Strong Local-Field Enhancement of the Nonlinear Soft-Mode Response in a Molecular Crystal


Giulia Folpini, Klaus Reimann, Michael Woerner, Thomas Elsaesser, Johannes Hoja,  Alexandre Tkatchenko,

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.119.097404


The nonlinear response of soft-mode excitations in polycrystalline acetylsalicylic acid (aspirin) is studied with two-dimensional terahertz spectroscopy. We demonstrate that the correlation of CH3rotational modes with collective oscillations of π electrons drives the system into the nonperturbative regime of light-matter interaction, even for a moderate strength of the THz driving field on the order of 50kV/cm. Nonlinear absorption around 1.1 THz leads to a blueshifted coherent emission at 1.7 THz, revealing the dynamic breakup of the strong electron-phonon correlations. The observed behavior is reproduced by theoretical calculations including dynamic local-field correlations.
  • Figure
  • Figure
  • Figure
  • Figure

No comments: