射线衍射原理.pptx

Chap2BasicTheoryinX-,forexampleinadiffractiongrating,,电子受迫产生振动,向四周辐射同频率电磁波。同一原子内的电子散射波相干加强成原子散射波。由于晶体内原子呈周期性排列,各原子散射波之间存在固定位向关系而产生干涉作用,在某些方向相干加强成衍射波。。衍射花样反映了晶体内部原子排列的规律。Chap2BasicTheoryinX-rayDiffractionScattering散射ThechiefresultoftheinteractionofX--raysofthesamefrequency(energy)astheincidentX-raysinalldirections(butwithmuchlowerintensity).urswhenx-,x-raysscatteredincertaindirectionswillbe“in-phase”:⑴;⑵。X射线衍射理论所要解决的中心问题——在衍射现象与晶体结构之间建立起定性和定量关系。Chap2BasicTheoryinX-,butcanberesolvedintomanyatomicplanes,,bandc(length)anda,bandganglesbetween,and-thereciprocals(倒数)ofthefractionalintercepts(分数截距) TheReciprocalLatticeThereciprocallattice(倒格子)ofalattice(usuallyaBravaislattice)isthelatticeinwhichtheFouriertransform(傅里叶转换)ofthespatialwavefunctionoftheoriginallattice(ordirectlattice)?对于一种材料,如何预测它的衍射现象?HowdoweorienttheX-raysourceanddetector?Howdoweorientthecrystaltoproducediffractio