Ionization And Dissociation Of Oxycarbide Molecule In Intense Femtosecond Laser Fields

As ultrashort intense laser pulse technology develops the peak power raises constantly,when the intensity of the laser intensity of the external light field is equal to that of the intensity of the internal interaction of the molecule,the molecule interacts with the laser to dissociate and produces a lot of new physical phenomena.Through the study of spectral peak phenomenon in time-of-flight mass spectrometry on ion fragmentation,Information of ionization of related atoms and ionization and dissociation of related molecular can be obtained in strong femtosecond laser field.What's more,it is an important experimental proof that we can use femtosecond laser pulses to study the process of bond breaking of molecular reaction and control science assimilation reaction channel.The contents of this paper starts from the research background and significance of research progress in China and abroad on the atomic and molecular ionization and dissociation in an intense femtosecond laser field.The theoretical model of ionization and dissociation of atoms and molecules in an intense femtosecond laser field and the significance of CO₂ and CO molecules selected as sample molecular to study the ionization and dissociation behavior of oxycarbide are introduced.In theory related theory of ionization and dissociation of atoms and molecules in intense femtosecond laser field and the mechanism of occurrence and characteristics of dissociation and ionization of atoms and molecules from two angles of ionization and dissociation are analyzed.What's more,how the laser parameters such as wavelength,intensity,pulse width and polarization changes the degree of ionization and dissociation of atoms and molecules changes are discussed.The experiment scheme of the research of the ionization and dissociation in an intense laser field of oxycarbide molecules is designed.Meanwhile,the corresponding core experimental devices such as femtosecond laser light source system,time of flight mass spectrometer,vacuum acquisition system and detection system are given.The method for calibration of the spectrum peaks is discussed based on the principle of time-of-flight?TOF?mass spectrometer device,the air time of fight mass spectrogram is acquired and calibrated.Time of flight mass spectrometry of CO and CO₂ is obtained and the calibration is finished.When the laser intensity,laser polarization and ellipticity of the laser pulse was changed respectively,the trend change of the degree of ionization and dissociation of CO and CO₂ is studied.For CO₂ the corresponding ions become less when the laser field intensity decreases.When the laser intensity is reduced to 25% of the original laser intensity,ion yield peak will disappear completely.When the direction of the polarization changes,the ion yield of monovalent ions has little effect,but the ion yield of dissociated ions has a great effect.When the polarization state of laser pulse changes from horizontal polarization to vertical polarization.Ion yield of the dissociated ions enlarges.Meanwhile,with the ellipsometry of the laser pulse larger ion yield of ionized and dissociated ions become less.For CO the trend change of corresponding ions is same as that of CO₂ when the intensity of the laser pulse changes.But when the direction of polarization of the laser pulse changes the trend change of the corresponding ions of CO is opposite to that of CO₂.When the direction of polarization of laser pulse is horizontal polarization Ion yield of the dissociated ions have a maximum.At the same time,the Coulomb explosion phenomenon of C2+,C+,CO+?1,1?dissociated by CO₂ molecule in an intense field is found.Meanwhile,the initial kinetic energy when the Coulomb explosion happens is calculated.