A Method to Make Water Vapor Peaks Disappear During Measurement of Fourier Transform Infrared Microscopic Spectrum

Water vapor peaks(noise) often appear in infrared spectrum.It becomes sometimes serious in the infrared microscopy measurement due to the exposure of the microscope to air.In this study,a novel method to make water vapor noise disappear in the infrared spectrum was proposed.During the measurement of an infrared spectrum,the relative humidity in the infrared optical path was adjusted in time with dry N2 or relatively wet air depending on water vapor content in the system,respectively.By such a way,we can control easily at last that the average amount of water vapor in the sample measurement is equal to that in the background measurement.Therefore,the effect of water vapor on an infrared spectrum can be removed completely.This method was successfully applied to measure the microscopic infrared spectrum of steaic acid.