Launching Coherent Acoustic Phonon Wave Packets with Local Femtosecond Coulomb Forces

Ultrafast Dynamics Revealed with Time-Resolved Scanning Tunneling Microscopy: A Review

“…In 2020, Peller et al accomplished the detection and manipulation of ultrafast in-plane vibration-mediated molecular rotation with a THz STM pump−probe scheme. 87 In the experiment, the bistable magnesium phthalocyanine (MgPc) on NaCl/Cu (111) acted as the single-molecule switch that could be triggered by electron tunneling into the lowest 91 which is the collective motions of atoms in a lattice. In the experiment, they performed pump−probe measurement on the Au thin film grown on mica with paired, delayed, but identical THz pulses (Figure 4a).…”

“…A recent report by Sheng et al highlights the application of THz pump–probe STM in exploring and controlling the coherent acoustic phonon (CAP), 91 which is the collective motions of atoms in a lattice. In the experiment, they performed pump–probe measurement on the Au thin film grown on mica with paired, delayed, but identical THz pulses ( Figure 4 a).…”

“…(d) Fast Fourier transform of the time trace of I THz in (b). Reproduced with permission from ref ( 91 ). Copyright 2022 American Physical Society.…”

“…The combination of STM and pump–probe measurement enables the visualization of ultrafast dynamics at the single-atom or single-molecule level. It provides a unique platform where the inhomogeneous activities of individual molecules or low-dimensional materials can be tracked in both space and time, which otherwise are embedded in the ensemble average. , In this review, we investigate the approaches that integrate the pump–probe scheme with STM and discuss the recent studies revealing key insights into the dynamics of three types of quantum states: vibration, − orbital, − and spin. ,, …”

Avoided Level Crossing and Entangled States of Interacting Hydrogen Molecules Detected by the Quantum Superposition Microscope

“…THz-STM has been proven as a powerful tool to investigate the atomic-scale dynamics with femtosecond temporal resolution owing to the ultrafast voltage transient induced by THz pulses. − The voltage modulation across the STM junction introduced by THz pulses can respond to nonlinear I – V characteristics and produce rectification or a DC current. In addition, a property of H 2 that sets it apart from other systems studied by THz-STM arises from the resonant transition between the two levels in H 2 induced by the absorption of THz photons. , By combining the pump–probe technique with the STM, we were able to reveal the resonance frequency of the TLS and further demonstrated that this frequency can be split from the interactions with the TLS of nearby H 2 molecules.…”