R

Ragonediagram565●RRRadiance—RadianceLreferstotheradiationthatcomesfromanextendedsource.Itcorrespondstothepowertransmittedthroughasurfaceperunitareaofthatsurface,perunitsolidangle,giveninWsr−m−.Ref.:[i]Meyer-ArendtJR()Introductiontoclassicalandmodernoptics.Prentice-Hall,EnglewoodCliffsIHRadicalanion—isamolecule(mostlyorganicorco-ordinationcompound)afteraone-electronreduction,havingachargeof−,andbearinganunpairedelectron,i.e.,beingparamagnetic.JLRadicalcation—isamolecule(mostlyorganicorcoor-dinationcompound)afteraone-electronoxidation,hav-ingachargeof+,andbearinganunpairedelectron,i.e.,beingparamagnetic.JLRadiofrequencypolarography—Thistechniqueisbasedontheeffectoffaradaicrectification,whichisachangeofelectrodemeanpotentialunderthein-fluenceofsinusoidalalternatingcurrent[i].Theex-citationsignalisaradiofrequencysinusoidalalternat-ingcurrent(e.g.,kHz)whichis%amplitude-modulatedbyasquare-wavefrequencyofHz[ii].Tokeepthemeanpotentialconstant,alow-frequencyalternatingcurrenthastobesuppliedtotheelectrode.Theamplitudeofthiscurrentdependsontheradiofre-quencyandthekineticsofelectrodereaction[iii].IfthemeanpotentialiscontrolledbythepotentiostatandslowlychangedasinDCpolarography,theresponseisanS-shapedcurrent–potentialcurvecharacterizedbyamaximumandaminimum[iv].Theabsolutevalueoftheratioofpeakcurrents(R=imaximin)dependsonthecharge-transfercoefficient(Rifα.andRifα.),whiletheamplitude(imax−imin)de-pendsonthestandardrateconstantoftheelectrodereaction[v].Thetechniquewasusedforthedetermina-tionofkineticparametersofveryfastelectrodereactions(ks.cms−)[ii,iii,v].Undertheinfluenceofthere-actantadsorptiononthesurfaceoftheDME,theRFpo-larogramofthereductionbecomeshighlyasymmetri-cal(Rll)andmayexhibitonlyaminimum[v,vi].So,anion-inducedadsorptionofmetalcomplexesre-strictsthekineticmeasurements.Peakcurrentsofboththemaximumandminimumarelinearlyproportionaltothebulkconcentrationofadepolarizer.Thisistheba-sisforanalyticalapplicationofthemethod[vi].Refs.:[i]DossKSG,AgarwalHP()JScientIndResB:;[ii]BarkerGC,FairclothRL,GardnerAW()Nature:;[iii]AgarwalHP()ElectrochimActa:;[iv]BarkerGC()Faradaicrectification.In:YeagerE(ed)Transactionsofthesymposiumonelectrodeprocesses,Wiley,NewYork,p;[v]BarkerGC()AnalChimActa:;[vi]LovrićM,Komorsky-LovrićŠ,BranicaM()ChemAnalit:MLoRadiochemical(nuclear)methodsinelectrochemistry—Radiochemicalmethodsareappliedforthestudyofawiderangeofelectrochemicalsurfaceprocesses.Themostimportantareasareasfollows:adsorptionandelectrosorptionoccurringonthesurfaceofelectrodes;theroleofelectrosorptioninelectrocatalysis;depo-sitionanddissolutionofmetals;corrosionprocesses;theformationofsurfacelayers,filmsonelectrodes(e.g.,polymerfilms),andinvestigationofmigrationprocessesinthesefilms;studyofthedynamicsofelectrosorptionandelectrodeprocessesundersteady-stateandequi-libriumconditions(exchangeandmobilityofsurfacespecies);electroanalyticalmethods(e.g.,radiopolarog-raphy).Themostimportanttechniquesare:tracermeth-ods(i),Mössbauerspectroscopy(ii),neutronactiva-tion(iii),thinlayeractivation(TLA)(iii),ultrathinlayeractivation(UTLA)(iii),andpositronlifetimespec-troscopy(iv).Refs.:[i]HorányiG()Radiotracerstudiesofadsorption/sorptionphenomenaatelectrodesurfaces.In:WieckowskiA(ed)Interfacialelec-trochemistry,theory,experiment,andapplications.MarcelDekker,NewYork,pp–;[ii]KálmánE,LakatosM,KármánFH,NagyF,Klenc-sárZ,VértesA()Mössbauerspectroscopyforcharacterizationofcorrosionproductsandelectrochemicallyformedlayers.In:FreundHE,ZewiI(eds)Corrosionreviews.FreundPublishingHouse,TelAviv,pp–;[iii]HorányiG,KálmánE()Recentdevelopmentsintheap-plicationofradiotracermethodsincorrosionstudies.In:MarcusPH,MansfeldF(eds)Analyticalmethodsincorrosionscienceandengineer-ing,CRCPress,BocaRaton,pp–;[iv]SüveghK,HorányiTS,VértesA()ElectrochimActa:GHRadiotracermethodstracermethodsRagonediagram—Plotofpowerdensityvs.en-ergydensity(orviceversa)forelectrochemicalpowersources.Asshownbelow(actualdatamayvarydepend-ingonsourceandtimeofdataacquisition)abroadvari-566Randles,JohnEdwardBrough●RRagonediagram—Figure.Ragoneplotforselectedelectrochemicalenergyconversionandstoragesystemsetyofpossiblepowerandenergydensityexists.Thead-ditionallinesrefertodischargetimes,i.e.,thetimefor-mallyrequiredtoconvertallactivemassortofullydischargethecelltothedischargecutoffvoltage.Inotherdisplayssimilarlinesindicatetherange(maximumtrav-elingdistance)foranelectricvehicleoperatingunderspecifiedconditions.Refs:[i]KordeschG,SimaderG()Fuelcellsandtheirapplications.VCH,Weinheim;[ii]HolzeR()LeitfadenderElektrochemie.Teub-ner,StuttgartRHRandles,JohnEdwardBrough(Aug.,,England–Feb.,,England)Ran-dleswasoneofthefoundersofdynamicelectrochem-istry.HewaseducatedatDerbySchoolandCambridgeUniversity.Duringthesecondworldwar,Randleswasaconscientiousobjector,andwasallocatedtoaresearchestablishment.InhewasappointedLectureratBirminghamUniversity(U.K.),andremainedtherefor