COonrol of Formation Process of Water Clusters by Rotatilnal Energy

点击翻译按钮获取中文摘要

The formation process of water clusters were investigated experimentally, especially noticing the effect of the rotational energy of water molecules. The experimental apparatus is a conventional molecular beam machine with three stages of differential pumping. Water vapor were expanded freely through the nozzle into the vacuum to form a supersonic free jet. In the free jet, clustering of gaseous molecules takes place. The terminal concentrations of water clusters formed through the free jet were measured with a quadruple mass spectrometer. In this formation process, micro wave were irradiated on water molecules to excite the rotational energy level of water molecules. The obtained results are as follows ;(1) The dimmer concentration is little affected by the solute species, Ar or N_2. The concentrations of larger clusters in H_2O-Ar mixtures are always larger than those in H_2O-N_2 mixtures. This results implies the possibility of the control of formation process of clusters by the con … More trol of the internal energies of molecules.(2) The marked effect of the excitation of the rotational energy of molecules on the cluster formation were not observed in these experiments.(3) To increase the power of micro wave, the nozzle was inserted into the wavegaide but the marked effect of the excitation of the rotational energy of molecules on the cluster formation were not observed.The reasons of this ineffectiveness of the rotational excitation were supposed as follows ;(1) As the energy of the micro wave of 22.235GHz corresponds to the temperature difference of a few degrees, the amount of the energy which a water molecule absorbs is too small to have marked influence on the cluster formation.(2) Even in the room temperature, the distribution of the rotational energy of water molecules is so wide that the J=5->6 excitation of the rotational energy of a water molecule only gives a very small effect on its distribution, then it cannot have marked influence on the cluster formation. Less