Broadband Microwave Spectroscopic Studies Of Tert-butyl Halide And Benzene Compounds

Rotational spectroscopy is the basic science of obtaining the spectra of rotational transitions of molecules,free radicals and ions by using Fourier transform microwave spectrometer in the laboratory,and fitting the rotational spectra by using the principle of quantum mechanics.The hyperfine rotational transitions captured by Fourier transform microwave spectrometers and the most accurate molecular geometry and electronic structure thus fitted by rotational spectroscopy can bring standard models for the theoretical calculations of quantum chemistry,and provide spectral data support and frequency search guidance for radio detection of new molecules in deep space as well.This paper first introduces the research background and the recent advances of the rotational spectroscopy.A brief analysis was made through the comparison to indicate that the broadband Fourier transform microwave spectrometer,based on the linear chirp-pulse frequency modulation technology,has obvious advantages over traditional narrowband Fourier transform microwave spectrometer in efficiency during the measurement of molecular rotational transitions.The broadband Fourier transform microwave spectrometer has become the essential experimental apparatus in many rotational spectroscopic laboratories.In the Chapter 2 and Chapter 3,the instrumentation of the broadband chirped-pulse Fourier transform microwave spectrometer(CP-FTMW)was introduced.The spectrometer,independently designed and built by our laboratory with a working frequency range between 1 and 18 GHz and a bandwidth of 2 GHz in a single scan,has achieved high sensitivity and high resolution by adopting homodyne detection scheme and combing techniques such as multiple free induction decay and surface plasmon electromagnetic field enhancement.In the last two chapters,the rotational spectroscopic experiments of liquid tert-butyl halogen and solid benzene compounds were conducted.Through theoretical analysis and experimental verification,the molecular geometric structures of those molecules were accurately determined,which ful y proves the excellent performance of the broadband chirped-pulse Fourier transform microwave spectrometer built in the laboratory.