Multiplex advantage spectrometer

As in all Fourier transform methods in spectroscopy, the FTIR spectrometer benefits greatly from the multiplex, or Fellgett, advantage of detecting a broad band of radiation (a wide wavenumber range) all the time. By comparison, a spectrometer that disperses the radiation with a prism or diffraction grating detects, at any instant, only that narrow band of radiation that the orientation of the prism or grating allows to fall on the detector, as in the type of infrared spectrometer described in Section 3.6. 

In the infrared spectral range in general Fourier transform (FT) interferometers are used. In comparison with dispersive spectrometers FTIR enables higher optical throughput and the multiplex advantage at equivalent high spectral resolution. In... 

The transform from the interferogram to the spectrum is carried out by the dedicated minicomputer on the instrument. The theory of Fourier-transform infrared spectroscopy has been treated, and is readily available in the literature.21,22,166 Consequently, the advantages of F.t.-i.r. dispersive spectroscopy will only be outlined in a qualitative sense (i) The Fellgett or multiplex advantage arises from the fact that the F.t.-i.r. spectrometer examines the entire spectrum in the same period of time as that required... 

About 10 years ago, the ion-imaging method was developed for the measurement of the velocity of a quantum-state-ionized photoproduct [15,23]. This technique relies on using a position-sensitive ion detector at the end of a TOF mass spectrometer to measure the recoil of photofragments from the centerline of the spectrometer. This technique has a large multiplex advantage over other approaches. 

The second advantage of Fourier transform instruments is the so-called multiplex advantage. This is related to the fact that in a Fourier transform spectrometer, in con-... 

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