What is the necessity of using KBr in FTIR? Cant we do FTIR measurements without KBr? Does the end result change if we run FTIR on the sample with and without KBr?
FTIR spectroscopy is a method for identifying and analyzing the chemical composition of a sample. The most common method for preparing a sample for FTIR analysis is by using KBr (potassium bromide) as a matrix material. In this method, a small amount of the sample is mixed with KBr powder, and then the mixture is ground into a fine powder and pressed into a pellet. This pellet is then placed in the instrument for analysis.
However, it is possible to perform FTIR analysis without using KBr. Other matrix materials, such as sodium chloride, magnesium fluoride, and zinc selenide, can be used as well. However, KBr is the most widely used matrix material for several reasons.
One reason is that KBr is transparent in the mid-infrared region, making it an ideal matrix material for FTIR analysis. It also has a low absorption in the region where most samples absorb, which makes it a suitable choice for analyzing samples that have strong infrared absorption bands.
Another reason for the widespread use of KBr is its low cost and ease of availability. Additionally, KBr is chemically stable and does not react with most samples, making it a safe and convenient matrix material.
The choice of matrix material can affect the results of FTIR analysis. For example, different matrix materials can have different refractive indices, which can lead to different optical path lengths for the sample and can affect the spectral data.
In conclusion, it is possible to perform FTIR analysis without using KBr, but KBr is the most widely used matrix material for several reasons, including its transparency in the mid-infrared region, low absorption, low cost, and chemical stability. The choice of matrix material can affect the results of FTIR analysis, so it is important to choose the most appropriate matrix material for each sample.
Yes, it is possible to perform Fourier transform infrared spectroscopy (FTIR) without using KBr. One alternative to KBr is to use a diamond crystal. Diamond is a transparent material that has a high refractive index and is chemically inert, making it an ideal substrate for FTIR.
However, there are some drawbacks to using a diamond crystal for FTIR. For example, diamond crystals are more expensive than KBr pellets, and may be more difficult to handle and prepare. In addition, the high refractive index of diamond can lead to multiple reflections and interference effects that can complicate the FTIR spectrum.
KBr is a commonly used substrate for FTIR because it is relatively inexpensive, easy to handle, and provides a consistent background for spectral analysis. KBr pellets are typically prepared by grinding a small amount of KBr powder with the sample and compressing the mixture under high pressure to form a transparent pellet.
To collect an FTIR spectrum using KBr, the sample is usually ground to a fine powder and mixed with KBr in a 1:100 ratio. The mixture is then compressed into a pellet using a hydraulic press. The pellet is then placed in the sample holder of the FTIR spectrometer, and the spectrum is recorded by scanning the sample over a range of infrared wavelengths.
Ref:
https://unitechlink.com/ftir-analysis/
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