Dynamic Parameters Of NH₃ And Ar Studied By Fast Electron Scattering

It is obvious that atom and molecule are the basic elements of the substance which compose the world.The research on atom and molecule can extend the knowledgement of the structure of substance and advance the understanding of quantum behavior in the microworld.In this thesis I perform the inelastic scattering research about the NH3 and Ar based on the present high-resolution fast electron energy loss spectrometer in our laboratory at an incident electron energy of 1500eV with the energy resolution of 80meV and 90meV,respectively.More specifically:1.We have measured the generalized oscillator strengths of the A1A2"?X1A1 ex-citation of ammonia and discussed the validity conditions for the first Born approxi-mation.Besides,the vibrationally resolved generalized oscillator strengths of(0,v2)and(1,v2)excitation bands are reported for the first time.The weak dependence of the minimum position of the generalized oscillator strength on vibrational quantum number has been observed,which may due to the vibronic effects and violation of the Franck-Condon principle.By extrapolating the generalized oscillator strength to the zero mo-mentum transfer,the optical oscillator strength of the A1A2" state has been obtained,which gives an independent cross check to the previous results.Finally,based on the present result,the integral cross sections of the A1A2" state have been obtained system-atically from the threshold to 5000 eV with the aid of the BE-scaling method.2.Based on the relative flow technique,the generalized oscillator strengths of the monopole,dipole,quadrupole and octupole excitations of Ar have been determined sys-tematically.The accordance of monopole excitation 3p54p'[1/2]0 between the present 1500eV result and the 2500eV EELS result measured by Zhu et al.in K2<1.5 a.u.means that the first Born approximation should have been reached according to the consensus that the first Born approximation approached when the experimental results mutually match among different impact electron energies.While the unexpected de-viation appears compared with the result of x-ray inelastic scattering,which strongly indicates that the well accepted consensus may be problematic.The similar behavior has also been observed in the a1IIg+w?1 excitation of N2.