Ultrafast Nano-Spectroscopy | Page 8

Investigating exciton tunnelling & emission in vdW materials using ultrafast THz nanoscopy

Dual-beam path design of neaSCOPE + fs provides two independent ports for illumination and light collection . Combined with a patented high-NA parabola , it enables nanoscale pump-probe with integrated TDS or custom THz sources for time-resolved nanoscale analysis of quantum materials .
THz emission
Height , nm
500
250
0
t
sd ‘
Lifetime map
Binding energy
THz amplitude
0 1 2 3 4
Delay time , ps
y , µ m x , µ m
high
low
neaSCOPE + fs measured pump-induced changes of the local THz response ∆E THz along a surface of WSe 2 / WS 2 heterobilayer , providing precise maps of exciton binding strength & lifetime ( left ). Areas of prolonged lifetime indicate an advantageous local atomic registry ( e . g . stress , twist angle , etc .). In addition , interlayer tunneling of pumpgenerated excitons creates an out-of-plane current that
neaSCOPE + fs can directly probe femtosecond exciton dynamics at the nanoscale
T . Siday et al ., Nano Lett . 2022 , 6 , 2561-68
M . Plankl et al ., Nature Photonics 2021 , 15 , 594 – 600
acts as a source of a coherent THz emission . neaSCOPE + fs was able to measure this emission on a subcycle time scale , providing direct access to femtosecond charge transfer dynamics ( incl . tunneling current and time ( top ) constant . This demonstrates ultrafast in-situ investigation of Mott phase transitions , energy harvesting and light emission in atomically thin heterostructures at the nanoscale targeting the development of advanced functional nanomaterials .
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