The aim is to develop new analytical methods that allow the rapid, non-invasive and simultaneous determination of physico-chemical material properties. Infrared (IR), Raman and Laser Induced Breakdown (LIBS) methods are favoured for this purpose. Particular attention is paid to the applicability of the methods for routine use, for example by establishing portable measuring systems.

Vibrational spectroscopy

Vibrational spectroscopy, in particular infrared (IR), near-infrared (NIR) and Raman spectroscopy, is a key method for characterising chemical and physical material properties. These techniques provide molecular fingerprints and allow composition, structure and interactions in materials to be analysed.

1. Chemical material properties
Vibrational spectroscopy is suitable for analysing chemical bonds, functional groups and molecular interactions.

Examples and applications:

• Functional groups:
  - IR and Raman spectroscopy enable the identification of functional groups such as C-H, O-H, C=O and N-H by characteristic bands.
  - Applications: Polymer chemistry (determination of cross-linking degrees), organic synthesis (verification of reaction products).
• Molecular interactions:
  - NIR can analyse hydrogen bonding and hydration states.
  - Applications: Moisture analysis
• Reaction mechanisms and kinetics:
  - Real-time measurements with Raman or IR allow monitoring of chemical reactions.
  - Applications: Catalysis, battery research, polymerisation.
• Composition and purity:
  - Vibrational spectroscopy can be used to detect mixtures and impurities.

2. Physical material properties
In addition to the chemical composition, vibrational spectroscopy provides information on physical properties such as crystallinity, stresses or material defects.

Examples and applications:

• Crystallinity and amorphicity:
  - Raman can distinguish between crystalline and amorphous phases.
  - Applications: Polymers, ceramics, semiconductor materials.
• Phase transitions:
  - Temperature-dependent spectra show changes in molecular structure, e.g. during melting or glass transition.
  - Applications: Thermoplastics, metal oxides, battery materials.
• Stresses and defects:
  - Raman detects mechanical stresses and defects in solids (e.g. graphene, semiconductors).
  - Applications: Microelectronics, optical components.
• Surface and layer characterisation:
  - IR-ATR (Attenuated Total Reflectance) and Raman can analyse surface functionalisations and layer thicknesses.
  - Applications: Thin film technology, protective coatings.

3. Advantages of vibrational spectroscopy

• Non-destructive: Preservation of the material structure and properties.
• Speed: Fast analysis without time-consuming sample preparation.
• Flexibility: Analysis of solids, liquids and gases.
• Combination with other methods: Integration in microscopy (Raman microscopy) or thermal analysis.

4. Examples from practice

• Polymers:
  - Chemical: analysis of monomer composition and degree of cross-linking.
  - Physical: Analysis of crystallinity and phase separation.
• Semiconductors:
  - Chemical: detection of doping elements.
  - Physical: Analysis of lattice stresses and defects.
• Biomaterials:
  - Chemical: determination of proteins, lipids and carbohydrates.
  - Physical: Moisture content and material structure.

Conclusion
Vibrational spectroscopy is a versatile tool for the comprehensive characterisation of chemical and physical material properties. Its application ranges from basic research to industrial quality control and provides detailed insights into the structure and function of materials.