高分辨腔内衰荡光谱技术及其应用-化学物理专业论文.docxVIP

摘 摘 要 级。这些结果可以拟合80 K到296 K之间任意温度的光谱，有助于构建在此波 段的甲烷光谱理论模型，其在相关行星光谱学中有重要意义。 关键词：红外光谱，直接吸收光谱，腔内衰荡光谱，乙炔，氧化二氮，甲烷 ABSTRACTAbstract ABSTRACT Abstract The molecular spectroscopy in gas phase has been significant window to under- stand the molecular internal structure and properties，and has played an important role in physical and chemical research．The transition frequency,intensity and line pro— file can be directly retrieved from the gas·phase direct absorption spectroscopy,which is SO far commonly applied in analytical chemistry and physical chemistry．Among the direct absorption techniques，the cavity ring—down(CRD)technique is inherited with high sensitivity and simple implementation，and becomes more and more popular． The present work is mainly devoted to the construction of the cavity ring·-down spec·· trometer and its application in the absorption spectroscopy studies of some polyatomic molecules． The first chapter of the thesis presents the principle of the cavity ring··down spec·· troscopy．The history and development of CRDS was briefly reviewed．The second chapter is devoted to different components of the cavity ring—down spectrometer：laser source，mode matching，design of resonance cavity,signal detecting，data acquisition， and fitting of exponential decay curve．The probi ms encountered in the construction were also discussed．In order to evaluate its performance，the line profile of the acety— lene R(9)transition centered at 1 2695 cm～was recorded．Finally,the sensitivity of the present cavity ring—down spectrometer was determined as 7 x 1 0—11／cm．and the resolution was as high as 0．0001 cm～．The HWHM(Half width at Half Maximum) of the instrumental profile was estimated 4x 10—5 cm一．which reaches the limit of the laser line width．In the third chapter,the spectrometer was applied to record the 00006--0000 and 01 1伽1 10 bands of 15N14N160 and 14N15N160 in the near-IR region． the rotational assignments and band intensities were retrieved．Three 17“一∑亨bands of”C2H2 between 1 224