Question

Describe the Fourier transform IR spectrometer without a sketch, name
The advantages over a normal spectrometer.

Answer 1

FTIR uses interferometric technique to give absorbance and reflectance spectra of sample. It uses a Michelson interferometer setup where one arm oscillates with a certain velocity. Based on this velocity, the output light at the detector interferes constructively or destructively. This light is incident on the sample and transmitted light is collected at the detector. This means the resultant pattern at the detector is an interferogram. A Fourier transform algorithm is used to convert the time domain response of the sample (interferogram) into the frequency domain response thereby giving information about the absorbance/transmittance of all wavelengths in IR range by the sample at one go.

Advantages:

1] Because the output is an interferogram, the wavelength response is collected at a single time which makes it time efficient since normal spectrometer scans the response of the sample for every single wavelength one at a time.

2] The light incident on the sample is not passed through a slit for dispersing only a single wavelength. This increases the amount of light which can be passed through the sample.