Atomic Force microscopy (AFM)

Atomic force microscopes consist of a sharp tip fixed under a micron-sized cantilever; the instrument work by measuring the deflection of the cantilever as it scans across the surface of a the specimen, not only resulting in maps of surface topography, but also giving insight into some of its physical and mechanical properties.
Lateral resolution: depends on the nature of the sample and type/curve radius of the tip.
Accessible fields of view: between 30 µm and a few tens of nm.
 Contact Mode. The tip stays in contact with the sample when scanning, the vertical deflection is kept constant so that the z displacement of the cantilever provides a direct image of the topography of the sample surface (whereas the horizontal deflection gives insight on friction force between the tip and the sample). This mode also allows to perform punctual approach-retract curves, providing local characterizations of sample mechanical properties (inelastic and elastic deformations, adhesion force between the tip and the surface, etc…). Its main drawback lies in the fast degradation of fragile samples and tips, and the resulting artifacts.
 Tapping Mode. The tip is oscillating at the cantilever’s resonance frequency, and the contact with the surface is only intermittent. The surface topography is therefore imaged with minimal damages. Furthermore, the phase-lag (error signal) provides images, the contrast of which can be interpreted as a variation of surface viscoelasticity.

Equipment: Dimension 3000 microscope (Veeco - Bruker).
Available accessories: MFM tips, cell for experiments in liquid, backlit sample holder for thin layer of standard thickness, vibration-free box.

Cathodoluminescence microscope

The GEOPS catholuminescence system is composed of an Olympus microscope coupled to a cold cathode OPEA. This system allows diagenetic processes in carbonate or sandstone rocks to be observed using a Qicam camera.Système CL Orsay.