原子光谱学-X射线教学教程电子教案.ppt

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,16-3 The basis feature of X-ray,1,.Features of X-ray,1.Ionization action e,-1,2.Fluorescence action(use for detection and display of x ray),3.Photochemical action(act as normal electromagnetic way ),4.Biological effect(the basis of medical radiation treatment),5.Penetrating ability(wavelength,and the atomic number Z),2,.,diffraction of x ray,Lattice constant d,X ray wavelength,Aberration:2,dsin,So the condition of diffraction is,2,dsin,=k k=1,2.3.(16-4),That is Braggs Law,16-4 material attenuation law for x ray,1,.monochromatic x ray,The experiments showed that the x ray density attenuation rate in the material is proportional to the density of the point.,That is,we obtain:,:linear,attenuation constant with unit:cm,-1,I,0,I(x)x,x=0,I=I,0,I,m,=/,m,:mass,attenuation constant,with unit:,cm,2,/g,X,half-thickness:X,1/2,or,X,m1/2,We get:,after penetrated n half-thickness,the density of x-ray:,2,mass,attenuation constants formula,K=const,3,4,at medical profession,=3.5 for water;air and human tissue.,(1),Z,m,more efficient to resist x ray.,(2),m,easier to be absorbed.,16-5,x rays applications,at medical profession,x ray are mainly used in diagnose and treatment at medical profession,.,1,.,Treatment,(1)x ray radiation treatment,(2)X-ray,bistoury,(surgical knife)for operation,2,.Diagnose,(1)photography and fluoroscopy,(2)X-CT(x ray computer aid transverse,tomography,横断层成像,),Photo rebuild theory.,X ray tube,x ray detector,Assignment:p327 13-9;13-10;13-11,13-12;,01-12-24;02-12-9;05-5-23,