| Photoionization of molecules has always been one of the hot research directions in the field of atomic and molecular physics.Synchrotron radiation source has become a powerful tool for the study of single-photon photoionization of molecules due to its high light source brightness,wide photon tunable energy range,and high collimation characteristics.Research on ionization-related physical processes,molecular electronic state structures,and kinetic processes of molecules based on synchrotron radiation sources can obtain information on ionization mechanisms,dissociation channels,and ion electronic state characteristics of related molecules,and help explain the complex ionization processes of molecules.The new physical mechanism contained in it has very important research significance.In this dissertation,the single photon double ionization of toluene,chlorobenzene and fluorobenzene was studied experimentally using a synchrotron radiation source combined with reflectance time-of-flight mass spectrometry.By measuring the photoionization efficiency curves of three benzene substituents at photon energy of 22eV-28 eV and using the least-squares fitting,the secondary ionization limits of toluene,fluorobenzene,and chlorobenzene molecules were obtained,which are in good agreement with the theoretical calculations.it is good.Excess energy(photon energy minus secondary ionization limit)is between 0-16 eV.The relationship between the ratio of parent divalent ions and monovalent ions and photon energy is analyzed in detail and compared with that of He atom.The analysis pointed out that in the above photon energy division,the physical mechanism of the three benzene substituents is the Knock-out mechanism.We also observed the resonance enhancement of the chlorobenzene and fluorobenzene double-ionization yields at specific photon energies,while the toluene molecule was not evident,indicating the influence of molecular structure on the single photon double ionization process. |
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