Content1. What is analysis FTIR?
1.1 What is FTIR?
1.2 Feature of analysis FTIR
1.3 Application of analysis FTIR
1.4 Advantage of analysis FTIR
1.5 Technical parameter of analysis FTIR2. Use of analysis FTIR
3. How to buy analysis FTIR?
What is analysis FTIR?
Fourier transform infrared spectrometer (FTIR Spectrometer
) is referred to as analysis FTIR
. It differs from the principle of dispersive infrared spectroscopy, an infrared spectrometer developed based on the Fourier transform of the interfered infrared light. It mainly consists of the infrared light source, diaphragm, interferometer (beam splitter, moving mirror, fixed mirror), sample chamber, detector and various infrared mirrors, laser, control circuit board and power supply. It can analyze samples qualitatively and quantitatively and is widely used in the fields of medicine and chemical industry, geology and mining, petroleum, coal, environmental protection, customs, gem identification, criminal investigation identification, etc.
What is FTIR?
Working principle of FTIR
The light from the source is divided into two beams by a beam splitter (similar to a semi-transmissive and semi-reflective mirror). One beam reaches the moving mirror by transmission and the other beam reaches the fixed mirror by reflection. The two beams are reflected by the fixed mirror and the moving mirror and then returned to the beam splitter. The moving mirror moves in a straight line with a constant speed, so that the two beams form an optical range difference after the beam splitter, resulting in interference. The interfering light passes through the sample cell after converging in the beam splitter, and the interfering light containing the sample information reaches the detector after passing through the sample, and then the signal is processed by Fourier transform to finally obtain the infrared absorption spectra of transmittance or absorbance with wave number or wavelength.Infrared spectra
are absorption spectra, which are produced by the absorption of infrared light at specific wavelengths when the vibrational energy levels of bond-forming atoms in a compound molecule jump. Only vibrations that cause a change in the dipole moment of a molecule can produce infrared absorption. Infrared absorption spectroscopy is mainly used for structural analysis, qualitative identification, and quantitative analysis.
The whole process of Fourier transform infrared spectroscopy measurement is that the spectrometer emits infrared light through the DUT, and as the infrared light passes through the DUT, it causes the molecules in the DUT to vibrate, while the molecules vibrate to absorb specific energy (different wavelengths of infrared light). The original interferogram is measured by the interferometer. This map is a time domain spectrum, which is extremely complex and difficult to interpret. Therefore, the computer then performs a fast Fourier transform calculation on the interferogram to obtain a frequency domain spectrum as a function of wavelength or wave number, i.e., an infrared spectrogram.
Feature of analysis FTIR
A. High signal-to-noise ratio
uses fewer optical components, and no grating or prism beam splitter, reducing the loss of light and increasing the light signal through interference, so the radiation intensity reaching the detector is large, high signal-to-noise ratio.
B. Good reproducibility
Fourier transform infrared spectrometer uses the Fourier transform to process the light signal, avoiding the errors brought about by motor-driven grating spectroscopy, so the reproducibility is better.
C. Fast scanning speed
Fourier transform infrared (FTIR) spectrometers perform data acquisition in the full wavelength range, so the resulting spectrum is the result of averaging multiple data acquisitions. Moreover, a complete data acquisition takes only one to a few seconds, while a dispersive instrument needs to test only a narrow range of frequencies at any given moment, and a complete data acquisition takes ten to twenty minutes.
In brief, analysis FTIR is characterized by strong characterization, fast analysis, no destruction of specimens, small number of specimens, easy operation, ability to analyze specimens in various states, high analytical sensitivity, and a wide range of applications (solid, liquid or gaseous samples can be applied as well as inorganic, organic and polymer compounds can be detected). It can be used in combination with chromatography (GC-IR) or TGA (TGA-IR) and has a strong characterization function.
Application of analysis FTIR
A. Identification of known specimens
The identification of known material refers to the comparison of the infrared spectrum of the sample with the infrared spectrum of the standard, which can determine the similarity and purity of the two compounds based on the consistency of the spectral peak position, wave number, peak shape and other characteristics.
B. Consistency determination of polymer materials
Different substances have different types of groups, and the way the groups are arranged is different, which makes this difference reflected in the infrared spectra with different peaks. Therefore, there will be some differences in the exhibited IR spectral fingerprints. By comparing the infrared spectra, the differences in the compounds contained in the samples or the differences in the structure of the compounds can be obtained, and thus the material consistency of different samples can be determined. Usually, the material consistency also needs to be combined with the product component content, product physical and chemical properties and other multi-dimensional analysis to get better consistency analysis results.
C. Foreign matter analysis
Microinfrared spectroscopy is the most commonly used analytical method for the analysis of the organic foreign matter. This method is based on the absorption peaks of functional groups in the infrared spectra of foreign matter to determine the chemical composition of foreign matter. A simple method is to search the spectral library through the instrument software and compare it with the standard IR spectra in the library to determine the chemical composition of the foreign matter, while in the face of complexity, FTIR is used in conjunction with other detection equipment to obtain information about the composition of the foreign matter or foreign matter.
D. Curing rate test
Curing rate is a characterization of the degree of curing of a colloidal sample before and after physical or chemical curing. The curing rate test using FTIR includes the following.
a. Observe the breakage and reorganization of functional groups during the curing process of the sample.
b. The mechanism of the curing reaction.
c. Determining the extent of the curing reaction.
d. Test the curing rate of the sample, etc.
The technique applies to thermosetting resins such as epoxy resins, polyurethane resins, vinyl addition polymerized silicone rubber, etc. The purpose of the curing rate test is that the curing rate (degree of cross-linking) test can effectively observe the degree of reaction of cross-linked cured samples and control the material properties.
Advantage of analysis FTIR
Fourier transform infrared spectroscopy with the addition of a microscope can be used for microscopic infrared spectroscopy, with the following advantages.
A. High sensitivity
The detection limit can be as low as 10 ng, and a few ng of the sample can be obtained with a good IR spectrogram.
B. Micro-zone analysis
Microscopic measurement of apertures down to 8 microns or even smaller. Different parts of the sample can be easily selected for analysis as needed under microscopic observation. For non-homogeneous samples, the IR spectrograms of each phase of the sample can be measured directly under the microscope. For solid inhomogeneous mixtures, IR spectrograms of individual solid micron region components can be measured directly.
C. Simple sample preparation
Direct determination of reflection spectra for opaque samples.
D. Easy adjustment of the microscope light path
Microscopic observation and infrared spectral analysis are the same optical path, which makes it easy to achieve microscopic positioning of the part of the sample to be analyzed.
E. Sample retention
The original morphology and crystalline shape of the sample can be maintained during the analysis, and the sample is not destroyed.
Technical parameter of analysis FTIR
|Analysis FTIR||Technical parameter
|Spectral range||a. 4000--400cm-1 or 7800--350cm-1 (mid-infrared)
b. 125000--350cm-1 (near and mid-infrared)
|Maximum resolution||2.0cm-1 / 1.0cm-1 / 0.5cm-1
|Signal-to-noise ratio||15000:1(P-P) / 30000:1(P-P) / 40000:1(P-P)
|Beam splitter||Potassium Bromide Germanium Plating / Broadband Potassium Bromide Germanium Plating
|Detector||DTGS detector / DLATGS detector
|Light source||Air-cooled ceramic light source
Use of analysis FTIR
a. Check whether each part is connected before turning on the machine, in a zero state.
b. Turn on the voltage regulator switch. Wait for a moment, when the voltage is stable at 220V, turn on the host power. Preheat for one to two hours before the normal experimental operation.
c. The solid sample can be prepared by the press method during the experiment. KBr is mixed with the sample at a mass ratio of 100:1 and then finely ground under an infrared lamp using an agate mortar. The sample is then transferred into the tablet press and the tablet is fixed on the sample holder before testing.
d. Liquid samples can be measured by the liquid film method. Put 1-2 drops of the sample directly on one salt sheet of the detachable cell, then cover the other salt sheet and tighten the two salt sheets with the help of the fastening screws on the cell holder before testing.
e. Open the operating software. Collect the background values first, then insert the sample holder into the cuvette to collect the sample values. After 32 seconds of IR scanning, cut the spectrum into the current window to process it.
f. After the FTIR experiment is finished, turn off the power, restore the instrument to its original state, and perform the necessary finishing and cleaning work.
How to buy analysis FFTIR?
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