Studies On Ionization And Dissociation Processes Of Carbon Disulfide Molecules In Intense Femtosecond Laser Field

With the advent of femtosecond laser technology, the interaction of molecules with femtosecond laser field has aroused great interest. Many new non-pertubative physical phenomena, such as dissociative double ionization, above-threshold dissociation, coulomb explosion, high-order harmonic generation, have been discovered and widely studied. Carbon disulfide (CS2) molecule was viewed as essential molecule in astrophysics and aeronomy, and therefore its photoionization and photodissociation processes were always the focus of related fields like strong-field physics and femtochemistry. In this dissertation, we used dc slice ion imaging technology to investigate the ionization and dissociation process of CS2 molecule induced by an infrared femtosecond laser field with the laser central wavelength of 800 nm and the laser intensities in the range of 1013～1014 W/cm2. The dissertation is organized as follows,◆In the first chapter, we mainly introduce the ionization and dissociation mechanism of the molecules under the intense femtosecond laser field and the related ion-detective techniques, and also summarize the recent researches on triatomic molecules and our research work.◆In the second chapter, we mainly introduce our home-built dc slice ion imaging system, involving high-vacuum system, molecular beam system, femtosecond laser system, ion lens system, signal detection system and timing control system, and also present the data processing method in our work.◆In the third chapter, we mainly introduce the multi-photon dissociative ionization and coulomb explosion of CS2 molecule in the intense femtosecond laser field with the laser central wavelength of 800 nm and the pulse duratuion of about 70 fs. The channels of fragment ions S+, S2+, CS+ and CS2+ are assigned by measuring their KER distributions and angular distributions. A qualitative analysis on possible three-body coulomb explosion channels of CS2 molecule is given. The dissociation process of molecular ion CS2a+ (a=2-4) is theoretically simulated by using a coulomb potential approximation, and the dissociation time of molecular ion CS2a+(a=2-4) is obtained. Moreover, it is confirmed that two alignment mechanisms coexists in our experiment.◆In the fourth chapter, we give a summary of our research work and an outlook in the future.