Investigations Of Synchrotron Radiation Dissociative Photoionization Of Isooctane And 1,2-epoxyoctane And Design Of Time-of-flight Mass Spectrometer

Ionization and dissociation are fundamental processes in atomic and molecular re-actions,which are widely distributed in the celestial body,plasma,combustion,nucle-ar reactions and etc.The research of atomic and molecular dissociative ionization has great significance in astrophysics,plasma physics,power source and related subjects.In this thesis,based on the optical method and electron scattering method,the dissociative ionization of atoms and molecules has been studied.Specifically,the photoionization dissociation of isooctane and 1,2-epoxyoctane have been studied at the beamline station of atomic and molecular physics in National Synchrotron Radiation Laboratory,and the appearance potentials of the dominative fragment ions have been obtained with most of them being reported for the first time.Combined with the theoretical calculations the corresponding dissociative ionization channels have been elucidated.A time of flight mass spectrometer has been redesigned and prepared for the multiple coincidence mea-surement of the electron energy loss spectrometer,and an ion detector based on the secondary-electron-emission has been developed to improve the detection efficiency.The main results and innovations of this work are as follows:(1)Using vacuum ultraviolet photons produced by synchrotron radiation,dissocia-tive photoionization of isooctane was measured in the photon energy region of 9.7-15.6 eV.The appearance potentials of the dominative ion fragments were determined.In addition,combining with G3 calculations the dissociative photoionization channels of isooctane were elucidated,and the formation enthalpies of the fragmented ions were obtained.Most of the physical and chemical parameters of isooctane were reported for the first time;(2)Dissociative photoionization of 1,2-epoxyoctane was investigated by synchrotron radiation vacuum ultraviolet photons in the energy region of 9.8-16.6 eV.Appearance potentials of the dominative ion fragments were determined,most of them were re-ported for the first time.Through comparing the experimental measurements with the theoretical calculations we proposed the dissociative channels for the photoionization of 1,2-epoxyoctane;(3)Based on the electron energy loss spectrometer,a new time of flight mass spec-trometer(TOF)was redesigned and fabricated,which can reduce the influence of the TOF to the scattered electron beam and the perturbation of the pulsed electric field to the data acquisition system.A new ion detector based on the secondary-electron-emission was developed which can improve the efficiency of the detector notably according to the electronic lens simulation.