FTIR Tutorial

Quiz 2 - Advantages and Disadvantages of FTIR

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Question 1
What is the Fellgett advantage of FTIR?
a. Increased throughput
b. FTIR is more infrared efficient than dispersive spectroscopy.
c. All spectral elements measured at the same time
d. FTIR is a simpler technique, and therefore easier to use.

The Fellgett, or multiplex advantage arises because all of the spectral elements are measured simultaneously. Thus, a spectrum can be obtained very quickly.

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Question 2
What is the Jacquinot Advantage?
a. High throughput.
b. Errors spread across the spectrum.
c. Highly accurate measurements.
d. Another way of saying multiplex advantage

The Jacquinot, or throughput advantage, arises because unlike dispersive spectrometers, FTIR spectrometers have no slits which attenuate the infrared light.

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Question 3
What is the Fellget disadvantage?
a. Slower scanning due to addtion of spectra.
b. There is no Fellget disadvantage.
c. High optical throughput
d. Errors spread throughout spectrum.
e. Only one sample.

This arises because all regions of the spectrum are observed simultaneously. Therefore, if noise occurs in one part of the radiation from the infrared source, it will be spread throughout the spectrum in an FTIR system.

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Question 4
Which technique can measure two spectra at once?
a. Dispersive spectroscopy.
b. FTIR spectroscopy
c. Neither.

Dispersive infrared measures 2 spectra (usually sample and background) at the same time.

It is a double-beam technique. FTIR is a single-beam technique.

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Question 5
What is the Connes advantage?
a. Higher optical throughput of FTIR instruments
b. Greater spectral bandwidth
c. Highly accurate frequencies
d. High S/N ratio

The Connes advantage is that FTIR gives very accurate frequencies in the spectrum - this enables processing techniques such as spectral subtraction.

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