High Resolution Laser Absorption Spectroscopy Of The V₄ Fundamental Band Of Fluoroform

Fluoroform?CHF₃?is an important greenhouse gas,and its high resolution and high precision spectral data are very useful in atmospheric physics and chemistry.It's a prototype molecule for studying the intramolecular vibrational energy redistribution?IVR?process due to a strong Fermi resonance interaction between the stretching and bending modes of the CH-chromophore motion,This thesis investigates the high resolution spectrum of v4 fundamental?C-H bending?of CHF₃ in the mid-infrared range,and the main contents are as follows:Firstly,having considered the working characteristics of distributed feedback quantum cascade lasers?DFB-QCLs?,some improvements have been made in the wavelength scanning method,data acquisition program and calibration algorithm to the available pulsed supersonic molecular beam laser absorption spectrometer.This new experimental setup is used to measure the absorption spectrum of the v4 fundamental band of CHF₃(v0?1377.8472 cm^-1)under the room temperature??293 K?and in the supersonic jet??50 K?in the spectral range of 1369.6-1385.8 cm^-1.Secondly,the observed spectrum is simulated and analyzed by the PGOPHER program.A total of 1547 rovibrational transitions have been assigned to the v4 fundamental band of CHF₃.The standard deviation of the least-square fit is about 0.0008 cm^-1.We obtain a set of molecular constants with higher accuracy than before and they are compared with previous results from both experimental studies and theoretical calculations.Besides the v4 fundamental band,two additional hot-bands are also observed.The band-origins of these two hot-bands are around 1373.748 cm^-1 and 1373.823 cm^-1.