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Thisspectrumisaplotoftheabundanceoftheionsversusmass/chargeInfraredSpectroscopyWavenumber,–4,cm–,–cm–1–cm–1Wavelength–µm–µm–1, µmThischapterfocusesonthemostfrequentlyusedmidIRregion,betweenandcm–1(toµm)Theultravioletregioncorrespondstonmandvisibleregiontonm. logoI⁄I=εorϵ=/Where,Io=intensityofincidentlightI=intensityoftransmittedlightε=molarabsorptivityl=pathlengthofsamplec= concentrationofsampleInstrumentationofUV-VisiblespectrophotometerTheinstrumentusedtorecordthespectraofmoleculesiscalledaspectrometer AbsorptionofultravioletandvisibleradiationAbsorptionofultravioletandvisibleradiationItisintendedpurelyasabriefintroductiontothetechniqueanditis ThermoSpectronic'spolicytocontinuallyaddtothisrangeofdocumentationforfurtherdetails,astheybecomeavailableThebasiccomponentsareSourceof radiationMonochromator3BasicPrinciplesofUV-VisMeasurementTheelectromagneticspectrumaninstrumentabletomeasurethespectrumofasampleinthe UV/VisrangeUltravioletSpectroscopy.ThesophisticateddoublebeamrecordingUV-Visiblespectrophotometercoverstheentirewavelengthrangeofnm.Inthe massspectrumgivenbelowisthebasepeak.UV-visiblespectroscopybasedonBeer-Lambertlaw.DefinitionsandUnitsUltraviolet-visible(UV-vis)spectroscopy isusedtoobtaintheabsorbancespectraofacompoundinsolutionorasasolidwhereνisfrequency(inseconds),cisthespeedoflight(3×ms-1),andλis wavelength(inmeters)Whatisactuallybeingobservedspectroscopicallyistheabsorbanceoflightenergyorelectromagneticradiation,whichexciteselectrons fromthegroundstatetothefirstsingletexcitedstateofthecompoundormaterialUltraviolet(UV)andvisibleradiationareasmallpartoftheelectromagnetic spectrum,whichincludesotherformsofradiationsuchasradio,infrared(IR),cosmic,andXraysPDFInthisapplication-orientedbookletthefundamentalsof UV/VISspectrophotometryarefirstexplainedbeforefocussingonitsmainuseinFind,readandcitealltheresearchyouPrincipleofUV-VisibleSpectroscopy: ThePrincipleofUV-VisibleSpectroscopyisbasedontheabsorptionofultravioletlightorvisiblelightbychemicalcompounds,whichresultsintheproductionof distinctspectraUV-VISspectroscopyisconsideredastheoldestanalyticaltechniquethatcanbedefinedastheν=c/λAbsorptionofvisibleandultraviolet (UV)radiationisassociatedwithexcitationofelectrons,inbothatomsandmolecules,fromlowertohigherenergylevelsThisdescriptionoutlinesthebasic principlesforthosenewtoUV-VisiblespectrometryTheabundanceoftheotherpeaksisshownrelativetothebasepeakBackgroundTheoryJesper ØstergaardAbstractThepresentchapterdescribestypicalinstrumentationandprinciplesofUV/VisiblespectrophotometryandUVimagingmeasurements Absorptionofvisibleandultraviolet(UV)radiationisassociatedwithexcitationofelectrons,inbothatoms,·DownloadchapterPDFIntroductionInUV-Vis spectroscopy,wavelengthisusuallyexpressedinnanometers(1nm=m)ØUVlightcanbeabsorbedbymoleculestoexcitehigherenergy(mostlooselybound) electronsfromlowerenergystatestohigherstates.Theabsorptionoflightasafunctionofwavelengthdependsonthestructuralpropertiesofmoleculesaswellas thesolventinspectrumeNHe+H2CNH+H2CNHm/z=m/z=•Thestrongestpeakisassignedan‘abundance’of%andcalledthebasepeakØSuch transitionscanbestudiedextensivelytounderstandthebindingenergyofthecorrespondingelectronsundergoingtransitionBackgroundTheorySpectroscopyis basedontheinteractionbetweenlightandmatterUV/Visspectroscopyisameasurementtechniqueinwhichtherecordingoftheabsorptionspectraofdifferent samplesusingultraviolet(UV)andvisible(Vis)lightisachievedbyaspectrophotometer,ieItfollowsfromtheequationsthatradiationwithshorterwavelength hashigherenergy,and,forUV-Visspectroscopy,thelow(shortChapterUV/VisSpectrophotometryandUVImaging