L8Chap4英文版原子物理.ppt

4Thealkalis,4.1Shellstructureandtheperiodictable_1,Thebuilding-upprinciple:electronsfilluphigherandhighershellsastheatomicnumberZincreasesacrosstheperiodictable.FullshellsarefoundatatomicnumberZ=2,10,correspondingtoheliumandtheotherinertgases.Theseinertgaseswereoriginallygroupedtogetherbecauseoftheirsimilarchemicalproperties,i.e.thedifficultyinremovinganelectronfromclosedshellsmeansthattheydonotreadilyundergochemicalreactions.However,inertgasatomscanbeexcitedtohigher-lyingconfigurationsbybombardmentwithelectronsinagasdischarge,andsuchprocessesareveryimportantinatomicandlaserphysics,asinthehelium-neonlaser.,4.1Shellstructureandtheperiodictable_2,4.1Shellstructureandtheperiodictable_3,Eachalkalimetalcomesnexttoaninertgasintheperiodictableandmuchofthechemistryofthealkalicanbeexplainedbythesimplepictureoftheiratomsashavingasingleunpairedelectronoutsideacoreofclosedelectronicsub-shellssurroundingthenucleus.Theunpairedvalenceelectrondeterminesthechemicalbondingproperties;sinceittakeslessenergytoremovethisouterelectronthantopullanelectronoutofaclosedsub-shell(seeTable4.1),thusthealkalicanformsingly-chargedpositiveionsandarechemicallyreactive.However,weneedmorethanthissimplepicturetoexplainthedetailsofthespectraofthealkaliandinthefollowingweshallconsiderthewavefunctions.,4.1Shellstructureandtheperiodictable_4,Table4.1Ionizationenergiesoftheinertgasesandalkalis,4.2Thequantumdefect_1,4.2Thequantumdefect_2,4.2Thequantumdefect_3,4.2Thequantumdefect_5,4.2Thequantumdefect_6,4.3Thecentral-fieldapproximation_1,4.3Thecentral-fieldapproximation_2,4.3Thecentral-fieldapproximation_3,4.3Thecentral-fieldapproximation_4,4.3Thecentral-fieldapproximation_5,4.3Thecentral-fieldapproximation_6,4.3Thecentral-fieldapproximation_7,4.3Thecentral-fieldapproximation_8,4.3Thecentral-fieldapproximation_1,4.3Thecentral-fieldapproximation_9,4.3Thecentral-fieldapproximation_10,4.3Thecentral-fieldapproximation_11,4.3Thecentral-fieldapproximation_12,Comlemrntairly:Naatomspectrum,原子外层电子能级的跃迁,2-1,光谱项,四个量子数:n主量子数；L角量子数,0/1/2S/P/D；S总自旋量子数，,或0J内量子数,2S+1(LS)个或2L+1(LS)个,J1/2/3称单/双/三重态,2-2,Na双线：能级能量差E决定589.0nm589.6nm,E=hc/,能级：Na原子基态与第一激发态,2-2,单