[The constant-in time DC component in the time-resolved FTIR spectroscopy].
The direct current component in the interferogram of conventional FTIR spectroscopy is expressed by integral(infinity)0 B(sigma)dsigma. However, in time-resolved FTIR spectroscopy, the direct current component Idc(tau) also depends upon tau, the time which IR signal appears. Idc(tau) is then represented by integral(infinity)0 B(sigma, tau)dsigma, called as constant-in-time DC component by us. Idc(tau) is proportional to the signal intensity B(sigma). Idc(tau) can not be filtered by any band pass filter. After Fourier transforming, the Idc(tau) converts to a strong peak at 0cm(-1) in the IR spectrum. We call it as constant-in-time zero frequency signal Btau(0). Either Idc or Btau(0) can be used to monitor a variety of experimental conditions, such as the variation of gas pressure, laser intensity, the carbon deposition on the optics, etc. They can also be applied to measure the instrumental response time and the band pass frequency.
Li
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Institute of Chemistry, Chinese Academy of Sciences, Beijing.
Kong
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