What is Raman spectrometer?
is mainly applied to research institutes, universities, and colleges in physical and chemical laboratories, biological and medical fields, and other optical aspects, to study the determination and confirmation of the composition of substances. It can also be applied to criminal investigation and the jewelry industry for drug detection and gemstone identification. Raman spectrometer
is known for its simple structure, easy operation, fast, efficient, accurate measurement, and ability to measure low wave numbers. The confocal optical path is designed to obtain higher resolution, which can be used for um-level micro-area detection on the sample surface and can also be used for micro-image measurement.Instrumentation of Raman spectroscopy
is included micro-Raman spectroscopy
, handheld Raman spectrometer, portable Raman spectrometer, confocal Raman spectroscopy, UV Raman spectroscopy, infrared Raman spectroscopy
Basics of Raman spectroscopy
When a beam of monochromatic light with frequency v0 is shone on a sample, the molecules can cause the incident light to scatter. Most of the light only changes its direction of propagation and thus scatters, while the frequency of the transmitted light passing through the molecule is still the same as the frequency of the incident light, and this scattering is called Rayleigh scattering. There is another type of scattered light in which not only the direction of propagation is changed, but also the frequency of that scattered light is changed so that it differs from the frequency of the excitation light (incident light), and therefore the scattered light is called Raman scattering. In Raman scattering, the scattered light frequency that decreases relative to the incident light frequency is called Stokes scattering, and conversely, the scattering that increases in frequency is called anti-Stokes scattering. Usually, stokes scattering is much stronger than anti-Stokes scattering. Raman spectrometers
usually measure mostly Stokes scattering, which is also collectively referred to as Raman scattering.
The frequency difference “v” between the scattered light and the incident light is called the Raman shift. The Raman shift is independent of the frequency of the incident light; it is only related to the structure of the scattered molecule itself. Raman scattering occurs due to a change in the polarization rate of the molecule (a change in the electron cloud). The Raman shift depends on the variation of the molecular vibrational energy levels. Different chemical bonds or groups have characteristic molecular vibrations, and ΔE reflects the change of the specified energy level, so the corresponding Raman shift is also characteristic. This is the basis on which Raman spectroscopy can be used for the qualitative analysis of molecular structures.
Raman spectroscopy applications
Application of Raman spectrometer
A. Application of Raman spectroscopy in chemical research
Raman spectroscopy is mainly used for structure identification and molecular interactions in organic chemistry. It is complementary to IR spectroscopy and allows the identification of specific structural features or groups of features. The size, intensity and shape of the Eastern Abdur-Rahman shift are important for the identification of chemical bonds and functional groups. Raman spectroscopy can also be used to determine the isomers of molecules by their polarization properties.
In chemistry, Raman spectroscopy of the catalyst itself and of the catalyst itself can provide structural information about the surface substances and can be used for real-time analysis during the preparation of the catalyst. At the same time, Raman spectroscopy is an important method for working with electrode/solution interfaces on the basis of which the structure and properties of the electrochemical interface structure can be further investigated, and the adsorption reactions at the molecular level and applied to the mentioned electro, etching and electroplating techniques.
B. Application of Raman Spectroscopy to Highly Fractional Materials
Raman spectroscopy can provide a lot of important information about the structure of highly fractional materials, such as molecular structure and composition, three-dimensional regularity, crystallization and orientation, intermolecular and surface and interfacial structures. The stereochemical purity of a polymer can have the width of the attribute Raman peak. The Raman peaks of randomly positioned samples or samples with mixed head and tail structures are weak and broad.
The Raman peaks are weak and broad, while the Raman peaks of highly ordered samples are strong and sharp.
C. Applications of Raman spectroscopy in materials science research
Raman spectroscopy is a powerful tool to study the grain boundary structure of substances in materials science. It can do a lot of work on phase formation interfaces and other topics.
a. Raman spectroscopy of thin film structured materials
Raman spectroscopy has become a method for the detection and identification of chemical vapor deposition (CVD) thin films. Raman spectroscopy can be used to study the structures of monocrystalline, polycrystalline, micro silica, and nonquantitative silicon, as well as the structures of layered thin films such as boron, permeated amorphous silicon, hydrogenated amorphous silicon, diamond, and diamond-like carbon. structures.
b. Study of superlattice materials
By measuring the Raman frequency shift of the strain layer in the superlattice, the stress of the strain layer can be calculated.
c. Study of Semiconductor Materials
Raman spectroscopy can be used to measure the distribution of semiconductor damage after ion injection, the composition of semi-magnetic semiconductors, the mass of the epitaxial layer, and the carrier concentration of the components of the epitaxial mixture.
d. Phase structure of Raman refractory materials
e. Raman spectroscopy of all carbon molecules
f. Quantum size effect of nanomaterials
D. Applications of Raman spectroscopy in biological research
Raman spectroscopy is an effective tool for studying biological macromolecules. Since the Raman spectrum of water is very weak and the spectrum is simple, Raman spectroscopy can be used to study the structure of biological macromolecules and their changes in a close to natural and active state.
E. Applications of Raman spectroscopy in herbal medicine research
The application of Raman spectroscopy in the research of Chinese herbal medicines includes the following items.
a. Chemical composition analysis of herbal medicines
High-performance thin layer chromatography (TLC) can effectively separate herbs but cannot obtain structural information of each component compound, while surface-enhanced Raman spectroscopy (SERS) has the advantages of narrow peak shape, high sensitivity and good selectivity, which can detect the chemical components of herbs with high sensitivity. The combination of separation technique of TLC and fingerprinting identification of SERS is a new method to analyze herbal components in situ by TLC.
b. Non-destructive identification of herbal medicines
Since Raman spectroscopy does not require the destruction of samples, it can identify herbal samples non-destructively, which is especially important for the study of valuable Chinese herbal medicines.
c. Stability study of herbal medicines
Raman spectroscopy is used to dynamically track the deterioration process of herbal medicines, which is a direct guide to predicting the stability of herbal medicines and monitoring the quality of herbal medicines.
d. Optimization of Chinese herbal medicines
For the complex mixture system of herbal medicines and proprietary Chinese medicines and compound prescriptions, it is possible to directly interact with bacteria and cells without any component separation and extraction, and directly use Raman spectroscopy to nondestructively collect the spectrograms of bacteria and cells, observe the damage degree of bacteria and cells, study their pharmacological effects, and conduct optimization studies of herbal medicines, proprietary Chinese medicines, and prescriptions.
F. Raman spectroscopy in gemstone research
Raman spectroscopy has been successfully applied to the field of gemological research and gem identification. Raman spectroscopy can accurately identify inclusions within gemstones, provide information on the genesis and origin of gemstones, and allow effective, rapid, non-destructive, and accurate identification of gemstone categories, such as natural, synthetic, and optimally treated gemstones.
a. Application of Raman spectroscopy in the study of gemstone inclusions
Raman spectroscopy can be used for the qualitative and quantitative detection of the chemical composition of gemstone inclusions. Using Raman spectroscopy to study the characteristics of inclusions within minerals, information about the genesis and origin of gemstone minerals can be obtained.
b. Application of Raman spectroscopy in gemstone identification
Raman spectroscopy tests micro-areas up to 1-2um, which has obvious advantages in gemstone identification and can detect extremely small impurities, microscopic inclusions and artificial adulterants in gemstones, and can meet the non-destructive and rapid requirements necessary for gemstone identification.
Raman spectrometer uses
Use of Raman spectroscopy
a. It needs to be warmed up before using the excitation light. Pay attention to the cleanliness of the end face of the Raman probe, because the dirty window piece will affect the test effect.
b. Before opening the instrument, you need to open the cover of the Raman probe first, and pay attention to the probe is forbidden to face people.
c. Try to wear protective glasses when using the Raman spectrometer. It is forbidden to look directly at the open Raman probe, regardless of whether you wear protective glasses or not.
d. Do not operate the software too fast and too often, for example, when scanning the background, 1-2 seconds before clicking the run button.
e. If you need to perform custom measurements with the laser in constant light mode, please fix the probe to avoid accidents. Also try to avoid the laser in the constant light state.
f. The trade-off of data should be steady, taking into account various factors, such as changes in iron values, changes in other elements, insertion of aluminum amount, excitation spot, excitation sound, etc. Sometimes it is necessary to regrind the sample analysis to verify, and sometimes it is necessary to excite several times to verify. In the analysis of the data are always subject to the standard steel content, to control the positive and negative deviation of the standard steel shall prevail. After each replacement of argon gas, the working curve must be renormalized. When the bottle pressure drops to 15 atmospheres, you need to replace the new argon; if the excitation spot is found to be white during the work, should also be replaced by another bottle of new argon.
g. After the instrument is used, you need to cover the protective cover of the Raman probe and put it properly.
h. After use, you need to turn off the laser, disconnect the spectrometer, turn off the software, and let the cooling fan blow for another 1-2 minutes before turning off the main power.
How to buy Raman spectrometer?
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