Microscopy

Description of the method

Highly magnified view of surfaces. The following technologies are available:

Analyses in the micro- to nanometre range:

• Scanning electron microscopy (SEM): An electron beam scans the sample surface; the interaction provides high-resolution topographical and chemical information.
• Scanning transmission electron microscopy (STEM):Same operating principle as SEM, but the beam penetrates the (thin) sample and provides information about the internal structures. 

Analyses at the atomic level:

• Scanning tunnelling microscopy (STM) and scanning tunnelling spectroscopy (STS): STM: At small distances (< 1 nm) between the conductive tip and the sample, a measurable tunnelling current flows, allowing individual atoms and their electronic properties to be visualised. RTS additionally provides electronic information about the density of states.
• Atomic force microscopy (AFM): A nanoscale-scale fine needle is pressed against the sample to be measured by means of a leaf spring, and the atomic forces cause the leaf spring to bend. Unlike STM, non-conductive samples can also be analysed. 
• Atomic force microscopy with IR coupling (AFM-IR):This hybrid technique combines the high spatial resolution of AFM with the chemical specificity of IR spectroscopy. The IR-induced thermal expansion of the sample is detected via the AFM tip, thereby providing chemical information with nanometre resolution.

Examples of applications

Analyses in the micro- to nanometre range:

Scanning electron microscopy (SEM)

• Characterisation of surface morphology and microstructures
• Particle measurement and shape analysis
• Quality control of coated surfaces
• Material testing of fracture surfaces and signs of wear
• Development of nanostructured materials

Transmission electron microscopy (STEM)

• Atomic structural analysis of nanomaterials
• Characterisation of interfaces and defects
• Phase distribution in nanostructures, chemical analysis at the nanoscale

Analyses at the atomic level:

Scanning tunnelling microscopy (STM) and scanning tunnelling spectroscopy (STS)

• Atomic resolution of conductive surfaces
• Investigation of surface reconstructions and defects
• Analysis of adsorption processes at the atomic level
• Determination of local electronic properties

Atomic force microscopy (AFM)

• Topographical characterisation with atomic resolution of non-conductive surfaces
• Investigation of biomolecules under physiological conditions
• Characterisation of 2D materials and thin films

Atomic force microscopy with IR coupling (AFM-IR)

• Investigation of degradation processes in materials
• Development of functional coatings
• Quality control in microelectronics
• Chemical mapping of polymer blends and composites
• Characterisation of membranes and cell structures

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