Bromobenzene Molecules And Between Two Bromobenzene Molecular Multiphoton Dissociation And Ionization Mass Spectrometry Studies

The compound of bromobenzene is widely applied in the production life. Thus, it exists in the soil and water in large quantity. Being the environment hormone class material, this kind of compound is harmful to the health of human body. Once it rises to the convection layer, the material will yield halogen atom by the ultraviolet ray photolysis. This will trigger a series of chemical reaction, and the ozone molecule is destroyed. And the course will cause the consumption of the ozone layer. Multiphoton ionization-dissociation process is studied in order that chemical reaction can be controlled better. So the study of photolysis of the monobromo-benzene class compound is significant to the protection of environment.In this thesis, the Multiphoton ionization-dissociation process of bromobenzene and 1,3-dibromobenzene is researched in detail through the mass spectra of the laser, molecular beam and flight time.(1)With the technique of multiphoton ionization and flight time mass spectra, the ionization-dissociation mass spectrogram of bromobenzene molecular can be detected under the effect of laser whose wavelength is 266nm and 355nm.After analysis, we get the conclusion that there is no obvious ionization-dissociation with the effect of the laser of 355nm, while under the effect of the laser of 266nm, MPIF-TOF mass spectrogram of bromobenzene molecular can be got with the method of mass spectra of multiphoton ionization-flight time. The experiment measured the dependency relation between the laser intensity and the signal percent of fragment ions out of all ions. Then, we analyzed the mechanics of multiphoton ionization-dissociation with the experimental results. Furthermore, we discussed the possible establishment of fragment ions such as C₆H₅⁺, C₅H₃⁺, C₄H₂⁺, C₃H⁺ . The result shows that the absorption of photon dissociation is the main channel, and most of ion fragments are produced by ion-fragment dissociation staircase. (2)In the same experiment condition the multi-photon dissociation-ionization process of 1, 3-dibromobenzene were researched. Under the effect of 266nm laser its process is also mainly parent molecule dissociation and ionization of neutral fragment. We analyzed MPIF-TOF mass spectrogram of 1,3-dibromobenzene molecular and observed the dependency relation between the laser intensity and the signal percent of fragment ions out of all ions. The result shows that fragment ions such as C₆H₅⁺, C₅H₃⁺, C₄H₂⁺, C₃H₂⁺, are mainly generated by ion-fragment dissociation staircase. We also deduced the possible dissociation channel of 1,3-dibromobenzene parent molecule.