A Study On Dynamics Of FHH System At Low Collision Energy

Molecular reaction dynamics is an interdisciplinary subject between physics and chemistry which studies collision action between single particles by quantum mechanics. There have been well developed theoretical and experimental methods for atom and molecular collision, these methods have been applied to different systems and led to lots of valuable results, but only a few of these applications are relatived to low energy collision. The experimental success in the Bose-Einstein condensation of atoms and molecules has generated much interest in cold and ultracold collision. At present, the study of cold collision is just unfolding.In this paper, the state-to-state probabilities and cross sections of FHH system at low kinetic energy have been calculated based on the coupled-channel hyperspherical coordinate theory.In Chapter One, the development of molecular reaction dynamics, the characters and progresses about low energy collision between atom and molecular have been introduced.Chapter Two is on the principle of calculation. Four kinds of commonly-used methods for solving the kinematics equations are briefly presented, and then a detailed depiction is given to the coupled-channel hyperspherical coordinate theory.In Chapter Three, the dynamics of H + HF is studied. The effect of rotational and vibrational excitation of reactant is analyzed separately. It is found that elastic collision is a dominant process at ultralow temperature, vibrational excitation is good for reaction and reactional channel of H '+ HF ( v , j )→F + H ' H ( v ', j') becomes a major process in reactional channels; the vibrationally excited reactants quench to the closest vibrational states preferentially; for rotationally excited reactants, the quenching process is much more efficient than reaction; resonance is found on cross section of H + HF reaction and proved to be the result of quansibound states of the H HF van der Waals complexes existing in reaction channel.Chapter Four presents the effect of rotational excitation forF + HH. The rotationally excited reactants do not facilitate reaction as mentioned in Chapter Three; the v'=3 state is closed and the major product's state is v'=2 when kinetic and rotational energy are very low, and it becomes the major product's state after the v'=3 state is open; the probability of ground vibrational state is very small; the position of resonance peaks for F + HH ( v = 0, j= 0) reaction is in good agreement with that in some literatures; rotational excitation doesn't prevent resonance from occurring, but it reduces the intensity of resonance and cuts from the corresponding kinetic energy a value, which is the energy difference between the two rotational states.