Custom High Performance SPM
This scanning probe microscope (SPM) was specifically designed for nanoscale studies at the solid-liquid interface, specifically in electrolyte environments (ECSPM). Quantification of system noise limits in the tunneling mode, mechanical drift rates, and lowest mechanical resonance provided values of: ~10 pA/Hz1/2, 2 nm/min (XY) and 0.15 nm/min (Z), and 7.9 kHz respectively. Measurement of the closed-loop transfer function in the tunneling condition demonstrated linear feedback responses up to 4.2 kHz and 2.5 kHz in ambient and electrochemical conditions. Atomic and molecular resolution imaging have been achieved in ambient, in-situ and electrochemical imaging environments at scan rates up to 80 lines/second. A modular design approach has produced a highly flexible microscope capable of imaging and spectroscopy in tunneling (STM), tapping force (AM-AFM) and non-contact force (FM-AFM) modes.
In addition, a low noise all fiber interferometer has been designed and implemented for use as the deflection sensor in liquid environment frequency modulated atomic force microscopy (FM – AFM). Deflection noise densities of 2 fm/?Hz have been achieved using commercially available cantilevers in both ambient and liquid environments. The low noise interferometer works without the need for differential detection, special focusing lenses, or polarization sensitive optics, dramatically simplifying measurements. True atomic resolution imaging of muscovite mica by FM – AFM in water has been demonstrated using the developed deflection sensor.
Atomically resolved ECSTM image of the iodine-modified Au (111) surface (left) and rotated-hexagonal superstructure (right) in 0.1M HClO4.
True atomic resolution FM-AFM image of muscovite mica acquired in pure 18.2 M? water.