| Atomic, molecular and optical physics (AMO) is an important research field of fundamental physics. Ultrashort and ultra-intense laser pulses, due mainly to their comparable/stronger electric field strength to/than Coulombic field strength in atoms or molecules, have manifested themselves by revealing bunch of novel physical processes and novel concepts through investigation on ionization and dissociation. More importantly, studies in this direction may help understand the regular pattern of mass motion in extreme physical condition.Numerical simulation has always been a powerful means in the field of strong light interaction with atoms or molecules. Based upon the well-developed quantum mechanics theory, many real or ideal models have been proposed for atoms or molecules in so far as their interaction with light is concerned. Numerical solutions or computed data have served duties in either instructing experimental measurement or predicting conclusions.To that end, the presented dissertation focueses on the so-called charge resonance enhanced ionization (CREI) effect and electron correlation/entanglement effect in CREI, by perfoming ample computer calculation on a 1D three-proton-two-electron model of H3+. Our research work and the obtained results are outlined as:(1) Model: Under the condition of Born-Oppenheimer adiabatic approximation, a suitable model for H3+ wasset up.(2) Numerical computation: Using imaginary time relaxation, symmetric split-operator scheme and pseudo-spectra method, we find solutions to either stationary or time-dependent Schroedinger equations for ground state wavefunction or time-evolved wavefunctions. Two varying ways, namely the non-ionization probability and exponential fitting, are used for getting the variations of photoionization rate versus internuclear separation.(3) Physical mechanism: It is found that CREI effect appears under centain high laser intensity, and correlation or entanglement of the two electrons certainly affects the CREI in a profound way. Laser-induced electron localization, suppression of Coulombic potential barrier, and 3D dressed-state pictures are deployed to explain the observed behaviors. We also conducted some computer simulation of photoionization of a model CO2 molecular ion.(4) Experimant design: We design a prelimary plan of Time-of-Flight spectrometer aimed for measuring the ionization fragments. This set-up also serves as a 3D spectrometer for fulfilling image correlation and image labeling techinques in photoionization and photo-dissociation tests. Some experimental participation of a flash-lamp-pumped Nd:YAG laser helps contribute two perspective excitaion wavelengths at 1319nm and 660nm. |
