Ultrafast pump-probe nanoscopy enables study of dynamic processes in nano-materials by providing time-resolved spectroscopy with nanoscale spatial resolution.
Basic probing principle:
- focus a pump pulse to the sample to provide photoexcitaiton;
- focus an ultrashort probe pulse to the tip with controlled delay;
- the probe pulse creates an intense nano-focus at the tip apex that locally probes the sample properties through the near-field optical interaction and modifies tip scattering;
- detect the tip-scattered light using asymmetric nano-FTIR or THz-TDS to obtain complete spectral response of the sample (e.g. both absorption and reflectivity). Spatial resolution depends on the tip apex radius and is typically ~20 nm.
Challenge: Ultrafast nanoscopy requires accurate temporal & spatial overlap of two non-collinear laser beams from different spectral regions, while providing background-free detection of near-field signals.
neaspec pump-probe systems are equipped with patented dual-beam parabolic mirror and all-reflective chirp-free optics for accurate simultaneous focusing of laser pulses onto the tip. Combined with proprietary femtosecond laser sources and best light detection technologies (e.g. nano-FTIR, THz-TDS), neaspec delivers ready-to-use nanoscale pump-probe suitable for visible, IR and THz measurements.
neaspec’s ultrafast pump-probe nanoscopy is based on nano-FTIR setup comprising an asymmetric interferometer where the AFM tip and the sample are located in one of the interferometer arms. Such scheme enables the detection of amplitude and phase of the tip-scattered light, delivering sample reflectivity and absorption. Patented dual-beam parabola allows for simultaneous focusing of the pump beam to the tip. All-reflective optics facilitates the utilization of sources through mid- and near-IR, THz, visible and even UV spectral ranges. Integrated delay lines and pulse synchronization ensure effortless accurate temporal overlap of pulses and allow for detecting sample response as a function of time. An exclusive femtosecond laser designed specifically for nanoscale IR spectroscopy integrates both the pump and the probe sources and provides outstanding temporal resolution down to 10 fs for probing ultrafast dynamics
neaspec’s technologies compatible with ultrafast nanoscopy:
- nano-FTIR: the only method for nanoscale spectroscopy and hyperspectral imaging with broadband illumination sources.
- PsHet (Pseudo-Heterodyne): golden standard for nanoscale imaging and spectroscopy.
- THz-TDS (Terahertz Time-Domain Spectroscopy): Alternative integrated THz emission and detection without cryogenic components.