Atomic Force Microscopy (AFM) and Scanning Tunneling Microscopy (STM) (english version)

(Update February 24th 2023)

Person in charge

Patricia BERTONCINI

Atomic Force Microscopy (AFM) and Scanning Tunneling Microscopy (STM) allow the imaging of a sample surface by scanning a sharp tip localized at less than a few nanometers from the surface. Images recorded are very high resolution maps of different kinds of sample properties. There are several acquisition modes and very different samples can be studied.

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Equipments

AFM Nanowizard II JPK Instruments

• • • Scanner
      XY = 100 x 100 µm²
      Z = 15 µm
      Closed-loop

• • • Laser diode
      λ_infra-rouge (850 nm)
    • Modes
      Contact, contact intermittent
      Spetroscopie de force
      Spectroscopie de force longue distance (100 µm)
      Cartographie de force
      Nano-manipulation

 Multimode 8 Nanoscope V de Bruker

• • • 3 Scanners
      XY = 180 x 180 µm2 ; Z = 5 µm
      XY = 10 x 10 µm2 ; Z = 3,3 µm
      XY = 1 x 1 µm2 ; Z = 0,6 µm (résolution atomique sur HOPG ou mica)

• • • Laser diode
      λ_rouge
    • Modes
      Contact, intermittent contact modes
      Force spectroscopy

                                    Modes dedicated to the study of:
                                    - electric and magnetic properties: EFM, MFM, KPFM, C-AFM
                                    - mechanical properties: Peak Force QNM

                                        STM imaging and STS spectroscopy

 

Examples

Scanning Tunneling Microscopy (STM)

STM allows the imaging of the surface of a conductive material at the atomic scale and in the direct space. The tunneling spectroscopy mode of STM is employed to examine local density of state of the surface.

STM image STM of a surface of 1T-TaS₂, obtained in the constant current mode, at room temperature. The charge density waves superlattice and the atomic lattice can be seen simultaneously. (IMN sample: L. Cario, E. Janod, IMN images: P. Bertoncini).

Magnetic Force Microscopy (MFM)

MFM imaging is obtained using a magnetic tip. The measured forces result from the interactions between the magnetic tip and the sample surface.

Acier Duplex

 

Height image (left) and MFM phase image (right) of a Duplex steel surface showing magnetic domains (IMN sample: E. Bertrand, P. Paillard, IMN images: P. Bertoncini).

 

Nano-manipulation

The AFM tip can be used as a manipulation tool… For example, the logo of the Institut des Matériaux Jean Rouxel has been engraved drawn by following the chosen pattern while applying a pressure on the polymer surface.

Height images of a polycarbonate film surface before (left) and after « gravure » (right). (IMN images IMN : P. Bertoncini).

Mapping of the mechanical properties using force spectroscopy

 

AFM allows the recording of Force-Distance curves by approaching and withdrawing the AFM tip. Approach curves permit to determine the sample surface topography, quantify mechanical deformation and extract elastic modulus. Retract curves allow the measurements of adhesion and interaction forces, stretch molecules…

Example of force-distance curves (approach, in grey and retract, in black) recorded while bringing into contact a living cell (immobilized on a microlever) to a Petri dish surface before being detached (IMN curves: P. Bertoncini).