mass spectrometery质谱法

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1、MassSpectrometeryMassspectrometrygivesinformationonthemolecularoratomicweightofcompoundoratom.Massspectrometryisusedonmoleculesaswellaselements.Inmolecules,informationaboutthemolecularformulaandstructurecanalsobederivedbasedonfragmentationpatternsthatmayoccur.Inelements,theinformatio

2、ncanbeusedtocalculatetheaverageatomicmassandrelativeabundance(s)ofeachisotopeofanelement.TheMassSpectrometerhasFOURmajorstages:1.Ionization:2.Acceleration:3.Deflection:4.Detection:Example:Theoverallmassspectrumforchlorinelookslikethis:Whataretheisotopesofchlorine?Cl-35andCl-37Arether

3、epeakscorrespondingtothesetwovalues?______________Whataretheratiosoftwoisotopesinnature?_____________________________________Whataboutthe3linesattheendofthespectrum?________________________________Variousisotopesexistfordifferentelements:M++1canbefoundforelements:carbon,hydrogenandni

4、trogenM++2canbefoundforelements:oxygen,sulfur,bromineandchlorineOtherrecognizablefeaturesofsomeelementsare:ForbrominetheM++2peakisaslargeastheM+peakForchlorinetheM++2peakisone-thirdaslargeastheM+peakForiodinethereisalargegapbetweenaclusteroffragmentsandanM+peakat127FornitrogentheM+pe

5、akwillhaveanoddnumbervalueUltraviolet-VisibleSpectroscopyBasedonelectronictransitionsofconjugatedsystems(systemsthathaveunsaturation(s)andtheirelectronsaredelocalized).Sincepi-bondelectronsaremoreeasilyexcitedthansigmabondelectrons,theenergiesrequiredforthetransitionsareintheultravio

6、letregionbutoftenextendintothevisibleregion.ThusithasknownasUV-VISspectroscopy.CompoundsthatcontainunsaturatedgroupsthatabsorbintheUV-VISregionarecalled_____________________.Forexample,_______________isachromophoreduethesixdelocalizedelectrons.However,theamountofenergyneededtoexcitet

7、hesepi-bondelectronsisalsoaffectedbythesubstitutentsattachedtothechromophores.Thesesubstituentsarecalled_______________________.MostorganiccompoundsabsorbintheUVrangehowevermoleculeswithanextensivenumberofpi-electronswillabsorbinthevisibleregion.Exampleinclude:Beta-carotene,chlorophy

8、llandphenolp