A time-resolved infrared spectrophotometer capable of investigating samples exhibiting short periods of response to stimuli. The spectrophotometer comprises a rapid scan interferometer, a stimulus generator periodically producing a stimulus not in synchronism with the reference signal produced by the interferometer, a detector detecting the radiation emerging from the interferometer, a variable delay circuit producing a trigger signal after a delay with respect to the stimulus, a gate circuit converting the output from the detector into a discrete form in response to the trigger signal, a low-pass filter for detecting the envelope of the output from the gate circuit, an analog-to-digital converter converting the output from the filter into digital form, and a CPU which takes the Fourier transform of the output from the converter, for obtaining a spectrum.
Time-resolved infrared spectrophotometer