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| FTIR Spectroscopy |
Introduction:
The identification and characterisation of molecules is made possible by the sophisticated analytical technique known as Fourier Transform Infrared (FTIR) Spectroscopy. FTIR spectroscopy offers important insights into the chemical composition, structure, and functional groups contained in a sample by examining the distinct vibrational frequencies of molecules. The essential ideas, uses, and historical advancements of FTIR spectroscopy are highlighted in this article's introduction.
Fourier Transform Infrared Spectroscopy is known as FTIR. It is a method for examining how infrared light and molecules interact. Simply said, FTIR works by illuminating a sample with infrared light and determining how much of the light is absorbed at various frequencies by the sample. The resulting spectrum provides information about the chemical bonds present in the sample and can help identify and characterize different molecules. This technique is widely used in various fields, including chemistry, materials science, pharmaceuticals, and environmental analysis.
History:
The origins of FTIR spectroscopy may be traced back to the early nineteenth century, when scientists discovered relationships between the chemical structure of substances and their infrared spectra. However, substantial advances in the discipline did not occur until the late 1940s, owing principally to the introduction of interferometry methods.
Professor Arthur C. Hardy pioneered Fourier Transform Spectroscopy in 1949, revolutionising the way infrared spectra were collected and analysed. Fourier Transform Spectroscopy eliminates the requirement for scanning specific wavelengths by using interferometers to analyse the spectral components of a sample concurrently, resulting in faster and more accurate findings.
Dr. Peter Fellgett and Dr. Alan L. McWhorter improved the approach further in the 1950s, developing the concept of the Fourier Transform Infrared (FTIR) spectrometer. Their work helped to lay the groundwork for current FTIR spectroscopy by combining complex mathematics and signal processing to obtain specific molecule information from infrared spectra.
With the introduction of computers and advances in apparatus in the second part of the twentieth century, FTIR spectroscopy quickly acquired appeal across a wide range of scientific fields. Its applications ranged from fundamental research in chemistry and physics to medicines, materials science, forensic analysis, environmental monitoring, and industrial quality control.
Today, FTIR spectroscopy is a flexible and crucial instrument for a wide range of scientific inquiries. It is a priceless tool for both academics and business because of its non-destructive nature, high sensitivity, and capacity to analyse a broad variety of sample types. With the development of portable and miniaturised devices that allow for field applications and real-time analysis, FTIR spectroscopy has been able to broaden its potential and range of uses for tackling difficult scientific problems.
Principle
The interaction of infrared light with molecules forms the basis of FTIR spectroscopy. A variety of wavelengths that are longer than visible light but shorter than microwaves make up infrared light. A molecule's molecular bonds move and spin when infrared light interacts with it.
The stages below make up the FTIR spectroscopy principle:
1. Sample Preparation:
The sample is prepared by either solid-state or liquid-state methods depending on the nature of the sample.
2. Interferometry:
In FTIR spectroscopy, an interferometer is used to split the incoming infrared light beam into two paths. One path passes through the sample, while the other path bypasses the sample (reference path).
3. Fourier Transform:
The two separated light paths are recombined, and the resulting interferogram is obtained. The interferogram represents the interference pattern of the two light paths.
4. Data Collection:
The interferogram is then subjected to a mathematical transformation called a Fourier transform. This process converts the interferogram from the time domain to the frequency domain, resulting in a spectrum called an infrared spectrum.
5. Spectrum Analysis:
The resultant infrared spectrum comprises peaks that correspond to various vibrational frequencies of the sample's chemical bonds. The functional groups and chemical bonds present in the sample can be recognised and analysed by comparing these peaks to databases or known spectra.
Overall, FTIR spectroscopy use interferometry and Fourier transform methods to offer precise information on a sample's chemical composition and structure based on infrared light absorption by its molecules.
Comprison of IR and FTIR Spectroscopy
Infrared (IR) spectroscopy and Fourier Transform Infrared (FTIR) spectroscopy are two methods used to study how molecules interact with infrared radiation. In reality, FTIR spectroscopy is a subset of IR spectroscopy that has particular benefits over typical dispersive IR spectroscopy.
The obtained infrared spectrum contains peaks that correspond to different vibrational frequencies of the molecular bonds in the sample. By comparing these peaks with databases or known spectra, the functional groups and chemical bonds present in the sample can be identified and analyzed.
Infrared (IR) spectroscopy and Fourier Transform Infrared (FTIR) spectroscopy are closely related techniques used to analyze the interaction of molecules with infrared radiation. FTIR spectroscopy is, in fact, a specific implementation of IR spectroscopy that offers distinct advantages over traditional dispersive IR spectroscopy.
The study of the infrared part of the electromagnetic spectrum, which encompasses wavelengths ranging from 0.78 to 1000 micrometres, is referred to as IR spectroscopy. This area relates to molecular vibrational energy levels. When molecules absorb infrared light, their vibrational modes are stimulated, producing distinct absorption bands or peaks in the ensuing spectrum.
Dispersive IR spectroscopy has traditionally required sending a polychromatic infrared radiation beam through a sample and then analysing the transmitted or reflected light using a monochromator. The absorption properties of the sample might be measured by scanning across various wavelengths.
Contrarily, FTIR spectroscopy uses interferometry methods to concurrently measure the whole infrared spectrum. It doesn't need a scanning device. In FTIR, a broadband infrared source is used to illuminate the sample, and the mixed frequencies of transmitted or reflected light that arise are then sent via an interferometer. The produced interferogram gives details on all of the existing frequencies. The interferogram is then transformed from the time domain to the frequency domain using mathematical techniques (Fourier Transform), yielding the FTIR spectrum.
Speed, signal-to-noise ratios, and spectrum resolution are all benefits of FTIR spectroscopy over dispersive IR spectroscopy.
Because FTIR spectrometers can provide extremely accurate and comprehensive spectra, molecular components in a sample may be identified and characterised with higher precision. The capacity to monitor a larger range of wavelengths, extending into the far-infrared area, is another feature of many FTIR equipment.
In the bigger picture, FTIR spectroscopy is a more sophisticated and adaptable method of IR spectroscopy. It is a crucial tool in many scientific and commercial applications because it uses interferometry to analyse molecule vibrational energies more quickly, sensitively, and informatively.
Advantages of FTIR over IR Spectroscopy
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What type of information obtained through FTIR but not obtained through IR Spectroscopy
When compared to conventional dispersive IR spectroscopy, FTIR spectroscopy can give more detailed information about the vibrational modes of molecules. Additional molecular information may be acquired via FTIR, such as:
1. Spectral peaks with high resolution:
When compared to dispersive IR spectroscopy, FTIR spectroscopy has a better spectrum resolution. This allows for the detection and distinction of spectral peaks that are closely spaced, which can offer more precise information regarding molecule structure and bonding.
2. Fingerprint Region:
The fingerprint area is the infrared spectrum region below 1500 cm-1. This area is rich in information regarding molecular composition and structure. The greater sensitivity of FTIR spectroscopy in this area allows for the exact investigation and identification of complex compounds.
3. The far-infrared Region:
Traditional IR spectroscopy primarily concentrates on the mid-infrared area, however FTIR spectroscopy can extend into the far-infrared range (below 200 cm-1). The far-infrared range reveals important information regarding lattice vibrations, intermolecular interactions, and material solid-state characteristics.
4. Quantitative evaluation:
For quantitative examination of chemicals, FTIR spectroscopy improves accuracy and repeatability. FTIR instruments' improved signal-to-noise ratio and stability make them more ideal for accurate measurements of molecule concentrations and evaluations of sample purity.
5. Time-resolved measurements:
For the purpose of investigating dynamic processes taking place on brief timeframes, FTIR spectroscopy can be combined with time-resolved methods. FTIR can record changes in molecular vibrations over time and give insights into reaction kinetics, molecular dynamics, and structural changes by quickly capturing interferograms and using fast Fourier Transform algorithms.
FTIR spectroscopy, in comparison to classical IR spectroscopy, delivers more precise and in-depth molecular data, especially in terms of resolution, fingerprint analysis, expansion into the far-infrared region, quantitative analysis, and time-resolved observations.
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