Office of Science

Microscope: Scanning Probe, STM/AFM, PicoSPM

Scanning tunneling microscopy image of a conductive nanowire produced by bacteria Shewanella oneidensis
Scanning tunneling microscopy image of a conductive nanowire produced by bacteria Shewanella oneidensis Full Image (jpg 63 kb)

Quick Specs

  • Allows imaging of air and moisture-sensitive samples under controlled conditions
  • Capable of tetecting currents from 1pA to 100 nA
  • Can perform I/V spectroscopy in STM and current-sensing AFM modes

EMSL's Molecular Imaging, Inc. PicoSPM™ scanning tunneling microscopy (STM)/atomic force microscopy (AFM) supports a wide range of scanning-probe techniques used to examine surfaces of diverse materials such as conductive and nonconductive minerals, bacterial biofilms, and self-assembled protein monolayers. The microscope incorporates temperature control, fluid cells, and an environmental chamber that collectively allow imaging of air- and moisture-sensitive samples under controlled conditions.

The microscope supports most AFM imaging techniques, including contact and intermittent-contact modes of operation. The intermittent-contact mode is magnetically driven (MAC™ mode). In addition, PicoSPM incorporates the capability to examine conductive materials by STM and by current-sensing AFM. The microscope can detect currents ranging from 1 pA to 100 nA and can perform I/V spectroscopy measurements in both STM and current-sensing AFM modes.

The microscope is equipped with Teflon fluid cells for in situ imaging in liquids. The cells can hold aqueous and nonaqueous media and have flow-through capabilities, allowing users to perform real-time kinetic experiments while imaging the samples. Coupled with the electrochemical unit that includes a low-noise potentiostat/galvanostat, fluid cells can be used for imaging under electrochemical control both in the AFM and in the STM modes of operation.

Two temperature-controlled sample mounts can heat and/or cool samples from -30°C to 250°C. Additionally, the microscope is equipped with an environmental chamber that can be used to maintain samples in a controlled atmosphere during imaging. This allows users to maintain complete control of the imaging environment, and creates the capability to perform in situ kinetic measurements on a variety of systems from minerals to biological systems.

  1. Effect of Surface Site Interactions on Potentiometric Titration of Hematite (α-Fe2O3) Crystal Faces.
  2. Subsurface Synthesis and Characterization of Ag Nanoparticles Embedded in MgO.
  3. Mineral Association Changes the Secondary Structure and Dynamics of Murine Amelogenin.
  4. A solution NMR investigation into the impaired self-assembly properties of two murine amelogenins containing the point mutations T21→I or P41→T.
  5. Very Stable Electron Field Emission From Strontium Titanate CoatedCarbon Nanotube Matrices With Low Emission Thresholds.
  1. New finding shows a research area to expand in EMSL Radiochemistry Annex (Promising Science for Plutonium Cleanup )
  2. Shewanella proteins could be used to generate energy or immobilize contaminants (Wired Microbe Conducts Electricity)
  3. Scientists connect previous studies on electron transport in hematite (Grow Iron, Slow Pollution)