Scanning Probe Microscopy (SPM)
Atomic Force Microscopy (AFM)
Atomic force microscopy is a specific scanning probe microscopy mode where images of surfaces are acquired using mechanical, electrical, and magnetical interactions between a sharp tip (cantilever and tuning fork) and the surface. Many AFM modes have been published in the last 20 years, some of which are mainstream and others are more exotic. Up-to-date instrumentation such as the HF2PLL is required to support most of them.
Identified AFM trends are the move towards higher cantilever frequencies, multi-frequency operation, and multi-mode operation. Applications that previously performed on lock-in amplification below 1 MHz are moving into the regions of tens of MHz. Scientists demand scanning at ever increasing speeds and thus require instrumentation with small time constants, in order to capture very fast events.
- NC-AFM, constant excitation AFM
- NC-AFM, constant amplitude AFM
- Kelvin Probe Force Microscopy (KPFM): AM-KPFM, FM-KPFM
- THz Scanning Near-field Microscopy (SNOM)
- Multi-Resonance Modes
- Piezo Response
- Liquid AFM
- Multi-mode AFM
- Multi-frequency AFM
- Multi-Harmonic AFM
Scanning Tunneling Microscopy (STM)
As the very first instrument to demonstrate atomic resolution in real-space, from the IBM Zurich Laboratory, the Scanning Tunneling Microscope still continue to demonstrate amazing resolution especially in the field of STS (Scanning Tunneling Spectroscopy), spin-polarized STM, or in combination with light source (induced photo-current) or photo-detector (light-emitting STM). Specially coated tips now even allow to perform experiment in liquid with an Electrochemical STM and a bi-potentiostat.
High performance low-noise lock-in amplifier are therefore particularly valuable for multiple differential measurements such as dI/dV, d2I/dV2 or dI/dz measurements, Inelastic Electron Tunneling Spectroscopy (IETS) and 3D-Spectroscopy at large. Internal and external reference signals can also serve to enhance otherwise too weak signal from external modulation.
And now with the new UHFLI-BOX Boxcar averager, even time-resolved STS experiments can be addressed by averaging enough pulses to reach pA detectable current.
THz Scanning Near-field Microscopy (SNOM)
At the crossroad between laser and SPM experiments, Scanning Near-field Optical Microscopy (SNOM), hold many promises for both time and spatial resolution, especially in the field of plasmonics with the use of extraordinary optical transmission. With or without aperture, there is a large variety of different SNOM modes that originate from the interaction of light with mater at the nanoscale.
Many detection schemes, either homodyne, heterodyne or even pseudo-heterodyne (with interferometer), often require complex set-up that can be simplified with all-in-one multifrequency lock-in amplifiers that allow for fine adjustment of all parameters and internal generation and demodulations of AM/FM signals.