Skip to main content

A Method for the Determination of the Zero-Path-Difference Position in a Fourier Transform Infrared Spectrometer: Application to Magnetic Vibrational Circular Dichroism

Buy Article:

$29.00 plus tax (Refund Policy)


Some modern FT-IR spectrometers, without a white light source, use a pre-scan of the signal to determine the zero path difference for purposes of scan initialization. The interferograms in vibrational circular dichroism (VCD) and other low signal-to-noise ratio experiments have little or no centerburst, which can cause problems. This can lead to wasted data collections and to instabilities between successively collected blocks of scans. In this modification, a PbSe detector is used to detect frequencies above 2200 cm−1 extracted from a small fraction of the beam. This near-IR signal is then added to the demodulated differential signal to enable the instrument to initialize scans. Since, in this example, the VCD spectra are typically obtained below 2000 cm−1, there is no spectral interference between the two detector signals. However, use of two signals from different detectors can lead to phase problems, which have been solved with the use of polarization calibration methods. As an example, construction of such a modified spectrometer for magnetic VCD measurement is described in detail. At 0.5 cm−1 resolution, these modulated spectra evidence resolution of the rotational structure in the bands. Such data were unobservable with the unmodified instrument.

Keywords: Infrared; Instrumentation, FT-IR; Interferometry, IR region; Spectroscopic techniques

Document Type: Research Article


Affiliations: 1: Department of Chemistry, University of Illinois at Chicago, Box 4348, Chicago, Illinois 60680; present address: Chemistry Division, Argonne National Laboratory, Argonne IL 60439 2: Department of Chemistry, University of Illinois at Chicago, Box 4348, Chicago, Illinois 60680

Publication date: February 1, 1991

More about this publication?

Access Key

Free Content
Free content
New Content
New content
Open Access Content
Open access content
Subscribed Content
Subscribed content
Free Trial Content
Free trial content
Cookie Policy
Cookie Policy
ingentaconnect website makes use of cookies so as to keep track of data that you have filled in. I am Happy with this Find out more