Calibration of terahertz spectrum by using carbon monoxide

Terahertz time domain spectrometer is becoming an important tool for inspecting the molecular information located in terahertz region. In order to get reliable spectroscopy data, calibration of terahertz spectrum is discussed in this paper. We measured the terahertz absorption spectrum of carbon monoxide (CO) gas with our homemade spectrometer. Comparing the measured absorption frequencies with the corresponding standard data in JPL database, we got the error values, and their distribution law showed the values gave a linear correlation with the absorption frequency. Based on this correlation, an calibration model was established. We used the model to correct the experimental data, and the result showed the maximum error after correction was 8.6 GHz, which was an order lower than the error before correction. This states the model can be used to correct the error of the measured terahertz spectrum. At last, we draw a conclusion that the terahertz time domain spectrometer system is supposed to be calibrated, in this way, the terahertz spectrum of sample can obtain a high accuracy. The study contributes to the material identification and the construction of molecular spectroscopy database in terahertz region.