Experimental Research On Low-energy Collision Of Multiply Charged Fe～(3+) Ions

The study of the ion trap mass spectrometry and its correlative technology has been the advanced topics of those fields, such as, atom and molecular physics, biology and chemistry. The multiply charged ions (MCI) play an important role in those fields, such as atom and molecule physics, surface science, plasma physics, nuclear physics, and astrophysical. Our theoretical studies on motional character of single trapped ion considering of double frequency of trap field, and the experimental low-energy charge-transfer of MCI are systematically introduced.The motional characters of single trapped ion by using the method of function series expansion are studied when the trapping field of the ion trap mass spectrometry includes the non-linear component, namely double frequency of the micromotion (DFM). The Mathieu function, in which the trap field is DFM, is solved by using the function series expansion method. The effects of the first stable region and the secular motion and micromotion of single trapped ion are obtained under different parameters of double frequency. We find the secular motion frequency increased, the micromotion frequency decreased and the stable region of single trapped ion diminished with the increase of DFM.In the experiment of MCI, the N²⁺ ions are produced by electron bombardment in Paul trap and the charged transfer coefficient between N²⁺ and N2 are measured. The value of rate coefficient deduced from this measurement is 1.75(0.33)×10-9cm³Â·s^-1 and is consistent with previous data measured under the similar conditions, the value is also in good agreement with the Langevin rate coefficient. Consequently our experimental apparatus and its ability to measure charge transfer rate coefficient are tested. Then the Fe³⁺ ions with the mean energy about 5.1eV are created and confined by laser ablation combined with the technique of crossed ion beams cooling and the decay curve in the base vacuum is acquired in the ion trap mass spectrometry. Moreover the first measurement on the charge-transfer rate coefficient of Fe³⁺+N₂,H₂ are measured, corresponding rate coefficient are deduced to be 4.36(0.46)×10^-9cm³Â·s^-1, 1.64(0.22)×10^-10cm³Â·s^-1, respectively. The theoretical value of Langevin model are estimated and compared with our experimental results, the two results are coherent. These measurements will provide important data for a variety of charge-transfer collisions studies.