Many FT-IR spectrometers suffer from obsolete computers and electronics
boards. An alternative to discarding these systems is to have them converted
to step-scan operation by MAT. Step-scan data collection is appropriate
for many time-dependent measurements. In conventional rapid-scan FT-IR
spectrometers, a moving mirror within the interferometer is translated
at constant velocity to modulate the infrared radiation. The time dependence
of the modulation often interferes with measuremnets in which the spectral
properties of the sample are time dependent.
In step-scan operation the interferometer's moving mirror is stopped
during data collection, and moved stepwise between data collection points.
Consequently, the interferometric modulation has no time dependence during
data collection. Time dependence in the detector signal is then related
only to spectral changes in the sample. Step-scan FT-IR techniques have
been applied to a variety of time-dependent systems.