Raman Spectroscopy Techniques

What is Raman Spectroscopy?

Raman spectroscopy is one of the light scattering techniques, which is used for determination of vibrational modes of molecules. It is a popular, analytical and spectroscopic technique used in the research laboratorie worldwide. Raman imaging, Raman shift and Raman analysis are the popular terms associated with Raman spectroscopy.

What is Terahertz Raman Spectroscopy?

Raman spectroscopy applied to the scale of 1012 Hertz is called terahertz Raman spectroscopy. Terahertz is a unit of frequency and is represented as one trillion cycles per second or 1012 Hertz. For the derivation of terahertz Raman spectroscopy, some sophisticated tools are added to conventional Raman spectroscopy.

This article discusses some of the features of the terahertz Raman spectroscopy, its design, uses, and applications.

Pros of THz Raman Spectrometer over Raman Spectrometer

The Raman spectroscopy is simplified with microscopy, having some ultrafast narrow-line lasers, which spread across the whole visible spectrum, having output power ranging from milliwatts to watts.

One measurement is there - there is an optical method, which provides data in phase and nanostructure with terahertz (THz) spectroscopy, as it extends the measurement to less than 10 cm^-1 . 

There are better CARS/SRS techniques - There is a simplification of simulated Raman spectroscopy and microscopy with ultrafast lasers.

Wider selection - there are abundant narrow-line lasers to select from the visible spectrum, from milliwatts to watts.

Features of THz Raman Spectroscopy

In THz Raman spectroscopy, systems and laser components provide extension to Raman with unique data on nanostructures, polymorphs,adhesive curving, changes of phase, protein conformation and binding.

There are probes, spectrometers, microscope accessories, and well-plate readers, which simplify low-frequency Raman analysis. 

From an extensive range of ultrafast lasers for CARS and SRS spectroscopy and imaging, lasers can be chosen. Label-free microscopy can be performed in vitro and in vivo.

Ultrafast laser oscillators and scientific ultrafast amplifiers add value to the terahertz Raman spectroscopy.

Design of the Thz Raman Spectroscopy

Complete Raman analysis - In a single instrument, both the molecular structure and chemical composition are able to be analyzed.

Increases signal strength - from lower frequency regions, up to 10X higher signals can be obtained. 

Application-specific tools - reactor sampling probes, microscopy, well-plate readers, benchtop instruments.

Accessories and instruments extend the range of traditional Raman spectroscopy into the low-wavenumber region/THz, without restricting the capability for the measurement of the chemical fingerprint region.

It is preferably compatible with diverse analytical applications in the lab or at-line. The product is inclusive of bench spectroscopy modules, a platform of microscopy, an array of sampling probes and well-plate systems.

Well-plate system - Automated benchtop reader for analysis of common well plate formats. Easier to use graphical user interface, autofocusing, integrated polarized light microscopy vision system making speedy intra-well mapping easier.

High throughput screening - Rapid and complete analysis of overall well plates in a few minutes with no need of special sample preparation

Full automation - Batch file programming facilitates generally used processes.

From insertion of sample, autofocussing and generation of data, all are automated fully.

Complete data analysis - For overlaying Raman map on white light image, Clustering and Principle component analysis (PCA) are available

Spectroscopy probe (TR-probe) - This versatile tool is utilized for real-time process monitoring. It is available with multiple sampling options, inclusive of immersion probes, open beam and vial holders.

Rugged and reliable - Optical design, sealed and thermal stability play a role 

Diverse sampling options - Without any sample preparation, in situ analysis is performed

Compact fiber-coupled design - Enabling of flexible mountings for microscopes, reaction chambers, tabletop or handheld usage

Benchtop spectroscopy module - With different options of laser wavelengths, the existing Raman system can be connected to an integrated THz module.

Integrated laser source - For all Thz-Raman modules, 532 nm, 808 nm, 785 nm, 1064 nm or 976 nm can be chosen.

Inherent spectral calibration - There is simultaneous compilation of Stokes spectrum and anti-Stokes spectrum for all THz-Raman modules.

Versatile sampling -  It is available with a whole range of sample interface ancillaries

THz-Raman microscope platform - Every microscope is able to be turned into a high performing Raman microscopy along with the Modular upgrade. It is compatible with Nikon, Olympus, Zeiss and Leica formats.

Whole Raman spectrum - Simultaneously catching of chemical (+5 cm^-1 to +200 cm^-1) and structural (+200 cm^-1 and +2000 cm^-1 ) footprint of molecules in the regions 

Simple integration - Through fiber coupled output, easy integration with spectrometers can be done.

Operational flexibility - There is a simple optical in & out switch, which removes the system from the optical path.

Sureblock XLF filter systems - The pre-aligned filter systems are used to speedily capture both conventional Raman data and THz-Raman data.

Extended frequency range - For obtaining both Stokes and anti-Stokes, capture of Raman spectra to within 5 cm^-1 can be performed.

Versatile operation - The module is available in free-space configuration and fiber-coupled configuration options.

Unmatched performance - Suppression of Rayleigh line suppression having OD greater than 8 happens.

Applications of THz Raman Spectroscopy

THz Raman spectroscopy is useful in

• Cocrystal screening in pharmaceuticals - pharmaceutical analysis, co-crystals and crystallization studies
• Crystallization and reaction monitoring - polymorphism, crystallization, degree of crystallinity and monitoring of phase
• Source attribution, drugs, explosives and hazmat detection - detection of explosives, source attribution,forensic analysis, CBRNE analysis and detection.
• Medical life sciences.
• High throughput screening using THz Raman - Polymorphs, crystallinity, polarized light, high throughput screening
• Polymorph identification in pharmaceuticals - Usage of low frequency THz-Raman spectroscopy in polymorph identification and screening.
• Quantification of degree of crystallinity with THz-Raman - Polymers, structural materials, pharmaceuticals, degree of crystallinity and amorphous materials.
• Determination of layer properties in two dimensional materials - Non-destructive structural analysis in real time, characterization of nanomaterials

Conclusion

A short introduction to the Raman spectroscopy has been given. Then, Thz Raman spectroscopy has been defined and some pros of THz Raman spectroscopy over the conventional Raman spectroscopy have been explained. Further, a few important features of THz Raman spectroscopy have been provided. Subsequently, the design of THz spectroscopy has been elaborated. Finally, applications of THz Raman spectroscopy have been briefed.