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Exploring the Secrets of Low Band Raman Signals
Date: 2025-09-18Read: 33
Raman spectroscopy is an analytical technique that reveals the molecular structure and chemical composition of a substance by observing the patterns of molecular vibration and rotation. This technology has a wide range of applications in fields such as chemistry, biology, and materials science.
Raman scattering
raman shiftIt is an important parameter in Raman spectroscopy, which represents the relationship between the scattered light frequency andincident lightThe difference between frequencies, usually measured in wavenumbers (cm)-1）Expressed as a unit. The range of Raman shift is usually around 4000cm-1 Up to 200cm-1 between. By observing and analyzing Raman shifts, information about various aspects such as material structure, properties, internal stress, and purity can be obtained.
Low band Raman signal and i-Raman PlusRaman spectrometer
We will shift the Raman at 200cm-1The following section is referred to as the low band range. Low band Raman spectra are usually disturbed by strong fluorescence backgrounds, and the spectral signals are weak, requiring high experimental conditions and data processing requirements. However, low band Raman spectroscopy can still provide important information about material structure and properties.
Raman spectra of L-asparagine
The red part in the above picture isL-asparagineIn the low band region, three distinct peaks can be clearly seen.
The i-Raman Plus Raman spectrometer adopts advanced technology and optimized optical design, enabling it to access a lower wavelength range of up to 65cm-1This means that it can provide more comprehensive and in-depth material analysis. Whether it is the study of protein properties, the detection of polymorphs, or even the determination of material structures, i-Raman Plus can provide crucial information.
I-Raman Plus Raman Spectrometer
Polymorphism detection
The most concerning issue in the pharmaceutical industry during drug development, production, and quality control is determining the structural form of its active pharmaceutical ingredients (APIs). Raw materials and drugs have polymorphism, characterized by the same chemical composition but different solid structures, which may affect bioavailability andTreatment indexIf the wrong form is used, it may result in compromised efficacy of the final drug product.
Example of pseudo polymorphic D-glucose
Alpha D-glucose（red）And α - D-glucose monohydrate（blue）Comparison of Raman spectra. We can see that at 65cm-1 ～ 200cm-1There are significant differences between the two pseudo polymorphs in the low band range.
The detection capability in the low band region has increased the overall detection sensitivity of the Raman spectrometer and improved its ability to distinguish similar materials.
Monitoring phase transition
Another important application in the industry is monitoring phase transitions or crystallization in chemical processes. Solid alpha sulfur samples were deposited on aluminum trays and heated to above the melting point (115.2 ℃) using a hot plate, resulting in a thickness of 83.6cm-1 The low band peak at the position widens and shifts, indicating a transition from the alpha form to the lambda form. Please note that there is no significant difference between the two forms within the conventional wavenumber range.
Comparison of spectra of sulfur after transformation from alpha form to lambda form
I-Raman Plus Raman spectrometer is required to measure as low as 65cm-1 The application of low band detection is a very valuable tool. The ability to characterize polycrystalline and dissolved forms can better control the production and formulation processes in the pharmaceutical and biological industries. In addition to the characterization of proteins, polycrystals, and phases, Raman spectroscopy can also be used to study semiconductor lattices, carbon nanotubes, solar cells, as well as various minerals, pigments, and gemstones.