Helium—Charged Titanium Films Deposited by Pulsed Laser Deposition in an Electron—Cyclotron—Resonance helium Plasma Environment

Titanium thin films incorporated with helium are produced by pulsed laser deposition in an electron cyclotron resonance helium plasma environment.Helium is distributed evenly in the film and a relatively high He/Ti atomic ration(-20%) is obtained from the proton backscattering spectroscopy.This high concentration of helium leads to a surface blistering which is observed by scanning electron microsocopy.Laser repetition rate little influence on film characters.Substrate bias voltage is also changed for the helium incorporating mechanism study,and this is a helium ion implantation process during the film growth.Choosing suitable substrate bias voltage,one can avoid the damage produced by ion implantation,which is always present in general implantation case.     

激光诱导等离子体中铜原子和铜离子的时空行为

通过光谱观察 ,考察了激光诱导铜等离子体的动力学过程和等离子体成分的时空行为 .不同能量的等离子体粒子 ,产生的机制不同 ,在时空演变过程中显示的行为不同 ,它们受背景气氛的影响也不同.By observing the optical emissions from copper plasma induced by laser ablationof a copper target, the dynamics of the plasma and the temporal and spatial behaviors of the plasma species are examined. The plasma is ignited from target ablation, evolves from the breakdown of the copper vapor to collisions between copper particles and energetic electrons. At the initial stage, the plasma contains large amount of copper ions and high-excited copper atoms, and then evolves to have low-energy copper...     

深入解读核心概念 有效落实教学目标——通过两则案例反思几何概型教学现状

人教版新教材必修3在概率一章中加入了“几何概型”一节,其目的应该是为了完善概率模型,以便能在高中段解释或解决更多的概率问题,确实几何概型的介入,为很多实际问题的解决提供了强有力的工具,但由于其核心概念涉及“无限”,因而对古典概型思想“根深蒂固”的教师和初涉概率思想的学生的“冲击”还是比较大的．是以对几何概型的教与学,都保持着一种“点到为止、不愿深究”的态度,