IR Absorption Spectroscopy Studies Of Atmospheric Interested Molecules

The development of the Molecular Spectroscopy has a long history, since the Newton divided the sunlight into seven single color light by using a prism in 1665. The developments of the laser and computer technology in last century also lead a revolution of the molecular spectroscopy.Among different kinds of studies on the polyatomic molecules, the high resolution spectroscopy of rotational and vibrational transitions contributes to the better understanding of the energy-level structure and intramolecular energy transfer. An observed spectral line yields the following information: frequency, intensity and line shape. The frequency corresponds to the difference of upper and lower energy levels. The intensity is proportional to the possibility of transition, which involves information from the energy surface and the dipole moment surface as well. Line shape is determined by many factors, which is the convolution of energy life time broadening function, collision broadening function, Doppler broadening function and instrumental function.The present work is devoted to record and analysis the highly excited vibrational state of interested atmosphere molecules. Mainly the work focuses on the line positions and intensities. The first chapter reviews the recent studies on the molecules concerning in this thesis, and presents different sensitive spectroscopy techniques used in the experiments; the second chapter presents the rotational analysis of the spectra of several molecules; the third chapter presents the line intensity studies of these molecules.In the first chapter of the thesis, we cite the HITRAN Database to review the studies on the molecules concerning in this thesis. We also present different highly sensitive spectroscopy techniques used in the experiments, it includes the Fourier Transform Spectroscopy (FTS), Intracavity Laser Absorption Spectroscopy (ICLAS), Cavity Ring Down Spectroscopy (CRDS).In the second chapter, FTS, ICLAS-VeCSEL were used to present a systematical investigation on IR spectra of N₂O, C₂H₂, CO₂. First, we briefly introduce the theory of the energy level and the select rules of the linear molecule. Then we show three types of the transition of the linear molecule.The absorption spectrum of the natural sample of nitrous oxide has been recorded at Doppler limited resolution with a Fourier-transform spectrometer in the spectral range...