Matrix Isolation Spectroscopy Of Some Atoms And Molecules

The idea of Matrix Isolation Spectroscopy (MIS) is to isolate atoms or molecules in an inertial matrix before spectroscopy studies. MIS is mainly applied in the deter-mination of the structures of molecules including reaction intermediates and transition states, and the study of the interactions between atoms or molecules. An advantage of MIS is that the studied molecules are well isolated, the molecular rotations are prevent-ed, therefor often leading to simplification of the spectrum. Particularly because of the dissipation in the matrix, some unstable molecules or reaction intermediates, which are hardly to be detected in the gas phase, can be trapped in matrix for relatively longer time for spectroscopy measurements. However, due to the existence of weak interac-tions between the studied molecules and the matrix host, the MIS spectrum is often different to the spectrum in gas phase. The present dissertation focuses on the study of the interactions between molecules in matrices, and their spectroscopy characters.The dissertation is organized as following:In the first chapter as a pretext, I give a brief introduction of MIS since it has been first introduced in the50’s of last century, and the development and applications. I will also present the configuration of the setup used in my lab, which is a combination of the matrix isolation and a Fourier-transform interferometer. The setup for the production of high-purity para-hydrogen is also presented. Para-H2can also be used as inertial matrix host.In the second chapter, spectrum of small molecules doped in matrices is intro-duced. Firstly, the spectroscopy of the CO2and H2O molecules isolated in neon matrices. By annealing the sample and changing the concentration of the implanted molecules, we have successfully changed the concentration of the CO2-H2O complex. The related spectroscopy analysis is also presented. Then the vibrational spectroscopy of water molecules isolated in molecular nitrogen is studied. The spectral shift and broadening due to the increasing temperature has been observed. Using a phonon cou-pling model, we give a reasonable interpretation on the experimental results.In chapter three, the spectroscopy study of the aniline molecules isolated in dif-ferent matrices is presented. Aniline is one of the simplest derivative of the benzene molecule, and it is also widely used in chemical industry. Through the comparison of the spectra in the gas phase, in matrices, and in the solid state at low temperature, we studied its vibrational spectroscopy and the dynamics.In the forth chapter, I present the spectroscopy of the ytterbium atoms isolated in noble gas matrices. The Yb atoms are excited by a laser (or a LED lamp). The fluorescence and the absorption spectrum of the excited molecules are detected. The energy structure, lifetime of the metastable state, and the dynamics have been studied. A model based on the potential surfaces is used to interpret the inter-system relaxation process in matrices.