Abstract by Brittany Knighton
R. Tanner Hardy
Chemistry and Biochemistry
Terahertz Waveform Considerations for Driving Lattice Vibrations into the Anharmonic Regime
High-field THz spectroscopy is applied to experimentally extract the shape of the interatomic potential energy surface (PES) along the E phonon-polariton vibrational coordinate in LiNbO3. We compare three THz sources to show that by optimizing the THz waveform for the 3.8 THz mode, we can drive the atomic motion to larger amplitudes than previously reported (~35% improvement using 15% lower peak-to-peak field strength), providing an accurate determination of the anharmonic PES within the range of motion. To maximize the atomic displacement, we show that the spectral amplitude at the resonant frequency of the mode is more important than the THz peak electric-field strength. Z-scan and simple THz pulse shaping measurements confirm this, providing important guidance for future measurements to experimentally investigate the anharmonic PES along specific vibrational coordinates in solid materials.