Infrared & Raman Spectroscopy


In our daily use of everyday objects, we ordinarily characterize materials by their color. The appearance of different objects relies on the distinct reflection and absorption features of the particular material. In the electromagnetic wave representation light is the summation of a broad band of waves with specific frequencies related to particular colors, with only a very small range being located in the visible region. The ultraviolet and the infrared region confine this visible part of the spectrum. Since a heated body emits energy in the infrared region, this part of the spectrum is also called heat (or thermal) radiation. Due to the specific molecular structure of many materials, the infrared radiation exhibits strong interaction with those materials. Similar to the color in the visible region, many materials can by characterized by their “color” in the infrared region, which comprises information that is not accessible by visible radiation.

The research gathered under the term ‘infrared spectroscopy’ is related to measurement methods, which exploit the interaction between infrared (IR) radiation and the sample under investigation. The IR-spectroscopic measurement technique is well established in a laboratory environment. However, the application of IR-spectroscopy for inline-monitoring in an industrial environment still requires a profound technical understanding – something which has been established at RECENDT through applied research projects conducted with industrial partners. For inline monitoring of industrial (chemical) processes, RECENDT represents an experienced partner for companies of sizes ranging from SMEs to multinationals. However, in addition to the applied research conducted in the infrared spectroscopy group at RECENDT, we have also established scientific research activities in order to continuously provide novel techniques for our applied research projects.

Applied Research

Near- infrared-spectroscopy represents a non-contact and non-destructive measurement technique, which enables real-time inline monitoring of real world processes. IR-spectroscopy is based on the interaction of infrared-radiation with the considered material. The characteristic absorption bands for IR-radiation are determined by the sample’s molecular structure, which permits access to chemical information like concentration of certain components in a chemical mixture, or the progress in chemical reactions e.g., curing of coatings. Furthermore, physical parameters like density or conductivity can be deduced indirectly from the chemical structure. Due to the high complexity of the chemical relations, sophisticated mathematical algorithms (chemometrics) are employed in order to achieve an automated evaluation of the (N)IR-spectroscopic data. As the utilized spectrometer enables a high measurement rate (up to 50 measurements / second), this concept enables quasi real-time measurements of process relevant parameters targeted for inline monitoring.

Inline-Process Control/ Quality Management in Fluids

Inline analysis provides a wealth of detailed knowledge on the particular steps used in most industrial (chemical) processes. However, the ideal measurement position in many industrial processes is often located in harsh environments. To overcome this problem we gain access to the measurement points with the aid of quartz fibers combined with specifically designed robust measurement probes. The utilization of optical fibers further enables the remote access to process information, which can be evaluated in a safe position with the sophisticated measurement instrument. A variety of probes are used to investigate substances in solids, liquids, or the gaseous phase. By implementing many of these probes at different points in the line, it is possible to evaluate and monitor the whole process at once.

Inline-Process Control/ Quality Management on surfaces

For fluid substances, a diverse range of measurement probes is commercially available. Therefore, almost any measurement position can be accessed by a simple mechanical design. However, in some applications measurements using standard probes is not possible. In this case, we are able to assist as a competent partner for the development of the entire optical measurement setup, by choosing the correct commercially available components such as, sources, optics, and detectors, and also by implementing them in a customized device. An example of such system development could be the monitoring of surface processes (layer thickness, curing of coatings) in an industrial environment.

Additionally, for pure surface reactions it is also possible to deduce bulk properties from a surface measurement if the sample consists of a homogeneous material.

IR Technology in the Industrial Environment

Despite many industrial applications requiring customized solutions, not all applications require the utilization of sophisticated and expensive spectroscopic techniques. Therefore, for particular applications low cost solutions are sufficient. Due to our long-term experience with optical components (sources, optics, detectors), we are qualified in providing assistance for customer specific problems. An example is the use of the existing pyrometer-technology to investigate the capabilities of this technique in an industrial environment.

Within the field of IR and Raman technology, continuously upstanding measurement methods are evaluated regarding their potential for the application in process monitoring. The polarization state, for example, is completely disregarded in the classical IR spectroscopy. For this reason a significant increase in sensitivity is not possible for certain applications on surfaces.

Industrial Applications

PAC – The research network

Process Analytical Technologies (e.g. Infrared Spectroscopic Methods) are able to monitor chemical processes inline and control them precisely, which enables perfect optimization.
We have conducted intensive research in this field since 2010 and can act as your contact point to the entire research network PAC -

Process analytics & process optimization

In food production (bio) chemical process steps are frequently performed, for example, in beer production.
With our expertise we can assist in the application of Process Analytical Methods, e.g. varieties of Spectroscopy, to safeguard and optimize your processes!

Spectroscopic imaging

The spectroscopic control of chemical compositions (e.g. of pills) can be achieved by implementing different technologies (NIR, MIR, Raman, and THz). Spatially resolved spectroscopy is also possible – moreover you can get a picture, for instance, of the API-distribution in the product!

Process optimization for batch-processes or continuous-processes

Through exact knowledge of the current conditions in a batch-reactor or in a continuous process, the chemical processes can be regulated precisely. Therefore it is often possible to reduce process temperature and time reserves. Energy saving significantly raises profits, and leads to a quick amortization of such process optimization. Our Spectroscopy experts can support you!

Point-of-Care – Diagnostics for blood and urine

Spectroscopic methods provide highly efficient analysis of blood and urine samples. These methods allow a quick determination of various clinical parameters under Point-of-Care (POC) conditions. With such modern technologies time-consuming laboratory analysis are not necessary, and in addition, minimal amounts of liquid can be reliably measured. Thus, such approaches can be applied to intensive care and paediatrics / neonatology, or on-site use for emergency doctors.

Point-of-Care – Diagnostic of malign changes of skin (in-vivo)

Modern technologies are able to provide an immediate assessment of suspicious changes in skin – ideally by combining several methods: for example, contactless Infrared or Raman Spectroscopy can create spectral/chemical fingerprints of skin changes, and the Optical Coherence Tomography (OCT) is able to show microstructural skin changes.

Spectroscopy in the product development, production and QA

For the production monitoring / quality control or the product development, spectroscopic technologies (NIR, MIR, Raman, THz) can play a significant role. These methods make it possible to obtain very precise measurements of mixing ratios, compositions, ingredients, reaction progresses, and similar chemical information without sample preparation and costly laboratory analyses.
Such real-time measured data provides an ideal basis for your process optimization!


If you are committed to providing high quality seeds, we can help you in the following ways:

  • Contactless determination of residual moisture
  • Quantitative and qualitative determination of seed ingredients (e.g. proteins, carbohydrates (sugar, starch) etc.)
  • Analysis of incrustation and pelleting
  • Evaluation of the vitality and germination capacity
  • Soil analysis (phosphates, nitrates…)
  • Outgassing of the seeds (e.g. during storage) may deliver information about the status and possible deterioration (e.g. fungal infection)

Ask our Spectroscopy experts!

Bakery products

In the field of bakery production our Spectroscopy experts deal with:

  • Incoming goods and monitoring of raw materials
  • Monitoring of mixtures and ingredients
  • Monitoring of the homogeneity of dough in different process steps
  • Characterization and process validation in coating process steps
  • Multimodal studies for the crystallization of chocolate
  • Online process optimization based on incoming goods inspection (measurement of the Raw-Material-Variability), and process modelling
  • Detection of foreign objects: THz scans are able to detect non-metallic foreign bodies
  • Detection of defective goods (e.g. cracked biscuits in a closed package, ready for sale)

Meat production / meat and sausage manufacturing

The meat production / meat and sausage manufacturing is another research and application field for our Spectroscopy group.

You may be interested in the following questions:

  • Is the work area absolutely clean or are biofilms forming on the surfaces?
  • How can the quality of a piece of meat be valuated?
  • In which production step is it decided whether the meat processed is “steak” or “minced”?
  • How can the origin of the product and a possible “bio” status be controlled?
  • Does the packaging guarantee that the quality produced will finally be delivered to the customer?
  • Is it possible to control the quality status (and the current BBD) of the sellable finished and packed product?  

Explosives or drugs identification

Spectroscopic methods allow the easy identification of substances. Using such methods makes it possible to identify explosives and to distinguish between non-hazardous materials and hazardous or illegal substances.

Moreover, with Terahertz Spectroscopy, such analysis can also be performed for substances inside closed and non-transparent containers / objects (e.g. letters and cardboard boxes).

Adhesive bonding processes

An adhesive bond can only be as good as the production process in which it was produced. Besides the optimum choice and quality of the adhesive agent, the preparation of the surfaces and the perfect process control also play important roles in ensuring utmost performance of the bond in terms of load capacity and fatigue strength.
By utilizing spectroscopic technologies we can help you to monitor and control all chemical parameters (e.g., in mixtures, reaction monitoring, cleanliness of surfaces, hardening) directly inline during the process.

Analytics for paper & the paper industry

Paper is an extremely diverse material and its characterization requirements are relevant for production, processing, and application. We can support you in many ways with our testing methods (IR & Raman Spectroscopy, THz Spectroscopy, OCT, and Laser-Ultrasound), for example, in chemical analytics (directly in the production process) and the characterization of surfaces and fibers for both absorbency and anisotropy.

Spatially resolved spectroscopy

Do you want to know the exact local distribution (in micrometer range) of your chemical components? With Mid-Infrared-Microscopy we can chemically characterize and measure materials and cross-sections (e.g. residues or inclusions) with a spatial resolution as small as 5 µm.

Process-Up scaling

When developing new processes, and especially when bringing a process from lab-scale to production-scale, spectroscopic technologies play a crucial role in guaranteeing optimum performance. We can assist with selection of the best-suited measurement technique. Combine your process expertise with our analytical and monitoring experience to optimize your processes and maximize your output.

Nano-Medicine & Pharmaceutical Development

We are unable to develop the API - this might be your expertise! But when it comes to carrier development and process upscaling, you can rely on our experience of the application of process for analytical technologies (e.g. spectroscopic techniques) to serve as a support unit for precision medicine / nano medicine / personalized medicine and pharmaceutical development in general.