What is the working principle of FTIR?
FTIR spectrometers rely on the same basic principle as NDIR analyzers, i.e., the fact that many gases absorb IR radiation at species-specific frequencies. However, FTIR spectroscopy is a disperse method, which means that measurements are performed over a broad spectrum instead of a narrow band of frequencies.
Which detector is used in FTIR?
FTIR transmission spectra (single beam spectra) are collected at a resolution of 2 cm−1 using liquid nitrogen-cooled detectors. For ferrous NO samples, spectra are taken with a mercury-cadmium-telluride detector from 1000 to 4000 cm−1.
What is meant by Michelson interferometer?
A Michelson interferometer is a tool used to produce interference between two beams of light. One beam hits a fixed mirror and the other hits a movable mirror giving different beam lengths which converge on a detector screen giving an interference pattern.
What is the IR source in FTIR?
IR sources FTIR spectrometers are mostly used for measurements in the mid and near IR regions. For the mid-IR region, 2−25 μm (5,000–400 cm−1), the most common source is a silicon carbide element heated to about 1,200 K (Globar). The output is similar to a blackbody.
What is the difference between FTIR and IR spectroscopy?
Raman spectroscopy measures relative frequencies at which a sample scatters radiation, unlike IR spectroscopy which measures absolute frequencies at which a sample absorbs radiation. FTIR spectroscopy is sensitive to hetero-nuclear functional group vibrations and polar bonds, especially OH stretching in water.
What are the principles of FTIR spectroscopy?
Principles of FTIR Spectroscopy In FTIR analyses, Infrared light from the light source passes through a Michelson interferometer along the optical path. The Michelson interferometer comprises a beam splitter, moving mirror, and fixed mirror.
What is a Michelson interferometer?
The Michelson interferometer is a device that divides a beam of radiation into two distinct paths and then recombines the two beams after introducing a difference in the two paths. Under these conditions, interference between the beams can occur.
What is an FTIR?
An FTIR is typically based on The Michelson Interferometer Experimental Setup; an example is shown in Figure 1. The interferometer consists of a beam splitter, a fixed mirror, and a mirror that translates back and forth, very precisely.
What determines the throughput of a FTIR interferometer?
The interferometer throughput is determined only by the diameter of the collimated beam coming from the source. Although no slits are needed, FTIR spectrometers do require an aperture to restrict the convergence of the collimated beam in the interferometer.