| 摘要 |
<p>This invention provides a method of determining a trace gas concentration in a gas sample utilising Fourier Transform Infra-Red Spectroscopy, said method comprising the following steps i) to iii) of: i) synthetically calibrating a spectrometer by the steps of: a) calculating a theoretical spectral response function for a series of candidate chemical substances; b) convolving said theoretical spectral response function with a spectrometer instrument response function corresponding to said spectrometer device so as to produce an expected response function for said series of candidate chemical substances; and c) utilising said expected response function as the calibration of said spectrometer device in the subsequent measurement of chemical substances; ii) determining a spectral window within which to fit a calculated spectral trace to an experimental spectral trace by the steps of: a) choosing a series of candidate windows; b) determining the likely error measure associated with a fitting of said spectral trace for each of said series of candidate window; c) utilising said likely error measure associated with each of said fitting to determine a final window having substantially the lowest likely error measure; and d) utilising said final window as said spectral window; and iii) utilising said calibration and said spectral window to fit a calculated spectral trace to a spectral trace measured by the spectrometer and to thereby determine the concentrations of constituent gases and/or the ratio of the concentration of one isotope isomer (i.e. isotopomer) to that of another isotopomer of the same molecular species.</p> |
