Angular Distribution Of Ejected Electron From The Eu4f⁷6p_1/26d Autoionizing States With The VMI Method

The angular distribution of ejected electron from Eu4f76p1/26d autoionizing states hasbeen investigated with velocity map imaging technique. The investigation of the angulardistribution of ejected electron from autoionizing state is the research on the autoionizationdifferential cross section which is on the basis of autoionization total cross section providedby autoionizing spectrum, therefore carrying out the research on the angular distribution ofejected electron from4f76p1/26d autoionzing state does not only give an physical insight intothe understand on characteristics of Eu atom, but also test the new theory of quantummechanics strictly. Simultaneously, the study on the angular distribution of ejected electronfrom4f76p1/26d autoionizing state can also provide the information about the direction of theejected electron.This thesis employs the isolated core excitation technique to excite the Eu atom from theground state4f76s28So7/2to the Rydberg states4f76s(7So)6d8D5/2,4f76s(7So)6d8D7/2and4f76s(7So)6d8D9/2through the intermediate states4f76s6p6,8P5/2,7/2by the first two dye lasers,then tuning the wavelength of the third dye laser, the Eu atom, which is in the Rydberg state,is populated to the autoionizing states4f76p1/26d by the technique of resonance ionization.The4f76p1/26d autoionizing state decays into an electron and a ion, due to it is unstable for theautoionizing state. The photo multiplier tube had been used to collect the autoionizingspectrum by which the autoionization total cross section has been provided.The wavelengths of the first two dye lasers can be fixed, then, the wavelength of thethird dye laser scans in a uniformly spaced way. Meanwhile, the electron lens focuses theejected electrons to the position sensitive detector to enlarge the signal produced by thecollision between the ejected electron and the position sensitive detector and to realize theposition detection. Phosphor screen displays the results of the position detection, also know asthe two dimensional distribution of the ejected electrons projected on the detector, and thecharge coupled device collects them. The two dimensional distributions could bereconstructed the ejected electron`s three dimensional distribution by the inverse Abeltransformation.The fitting order of angular distribution could be confirmed, depending on the angularmomentum, parity conservations that existed in the autoionization process and the limitationof the angular distribution parameter ak. The specific form of the angular distribution wasachieved by integrating the three dimensional distribution over the radius with the fittingorder of the angular distribution, the physical illustration on the principle of them followingthe photon energy also has been given in this thesis.