X-ray emission for Ar^(11+)ions impacting on various targets in the collisions near the Bohr velocity

X-ray emission from the collisions of 3 MeV Ar^(11+)ions with V,Fe,Co,Ni,Cu,and Zn is investigated.Both the x-rays of the target atom and projectile are observed simultaneously.The x-ray yield is extracted from the original count.The inner-shell ionization cross section is estimated by the binary encounter approximation model and compared with the experimental result.The remarkable result is that the Ar K-shell x-ray yield is diminished with the target atomic number increasing,which is completely opposite to the theoretical calculation.That is interpreted by the competitive consumption of the energy loss for the ionization of inner-shell electrons between the projectile and target atom.

Kinetics and Mechanism of Catalytic Reduction of U(Ⅵ)with Hydrazine on Platinum Catalysts in Nitric Acid Media

The kinetics of U(IV)produced by hydrazine reduction of U(VI)with platinum as a catalyst in nitric acid media was studied to reveal the reaction mechanism and optimize the reaction process.Electron spin resonance(ESR)was used to determine the influence of nitric acid oxidation.The effects of nitric acid,hydrazine,U(VI)concentration,catalyst dosage and temperature on the reaction rate were also studied.In addition,the simulation of the reaction process was performed using density functional theory.The results show that the influence of oxidation on the main reaction is limited when the concentration of nitric acid is below 0.5 mol/L.The reaction kinetics equation below the concentration of 0.5 mol/L is found as:−dc(UO_(2)^(2+))/dt=kc^(0.5323)(UO_(2)^(2+))c^(0.2074)(N_(2)H_(5)^(+))c^(−0.2009)(H^(+)).When the temperature is 50℃,and the solid/liquid ratio r is 0.0667 g/mL,the reaction kinetics constant is k=0.00199(mol/L)^(0.4712)/min.Between 20℃ and 80℃,the reaction rate gradually increases with the increase of temperature,and changes from chemically controlled to diffusion-controlled.The simulations of density functional theory give further insight into the influence of various factors on the reaction process,with which the reaction mechanisms are determined according to the reaction kinetics and the simulation results.

Nd L-shell x-ray emission induced by light ions

The L-shell x-ray of Nd has been obtained for 300-600 keV He2+ions impacting,and compared with that produced by H+and H2+ions.The threshold of projectile kinetic energy for L-shell ionization of Nd is crudely verified in the energy region of about 300-400 keV.It is found that the energy of the distinct L-subshell x-rays has a blue shift.The relative intensity ratios of Lβ_(1,3,4)and Lβ_(2,15)to Lα_(1,2)x-ray are enlarged compared to the atomic data,and they decrease with the increase of the incident energy,and increase with increasing the effective nuclear charge of the incident ions.That is interpreted by the multiple ionization of outer-shells induced by light ions.

Electron emission induced by keV protons from tungsten surface at different temperatures

The electron emission yield is measured from the tungsten surface bombarded by the protons in an energy range of 50keV–250keV at different temperatures.In our experimental results,the total electron emission yield,which contains mainly the kinetic electron emission yield,has a very similar change trend to the electronic stopping power.At the same time,it is found that the ratio of total electron emission yield to electronic stopping power becomes smaller as the incident ion energy increases.The experimental result is explained by the ionization competition mechanism between electrons in different shells of the target atom.The explanation is verified by the opposite trends to the incident energy between the ionization cross section of M and outer shells.