A Poor Person’s Approach to STM based Pump-Probe and Pulsed-ESR Methods*

One major appeal of STM investigations is the unique combination of atomic scale manipulation capabilities with the excellent spectroscopic insight into the electronic structure of 2D materials; providing quasi-static information due to limited preamplifier bandwidth. However, access to the time-domain would enable additional measurement modalities, ranging from the investigation of charge and spin dynamics to the mechanical motion of nanostructures. Despite the early demonstrations by Nunes and Freeman, the widespread implementation of pump-probe methods has remained elusive due to instrumental hurdles. Here we introduce a versatile, straightforward, and affordable setup to achieve nanoseconds time-resolution with minimal changes to an existing STM system [1]. Our setup consists of a dual-channel arbitrary waveform generator, a transfer switch, and a lock-in amplifier. We demonstrate its plug-and-play capability on a field-trip, providing immediate access to the spin-excitation of a magnetic molecule. We further expand our setup to match requirements for pulsed ESR excitations.
[1] F.D. Natterer, MethodsX 6, 1279 (2019)