简介:Magneticspectrumoftheelectromagneticioncyclotronwavesintheterrestrialplasmadepletionlayer(PDL)aresometimesobservedtohaveaBIF(bifurcated)signature,whereadiminutionaround0.5ΩpwithΩptheprotongyrofrequency,occursbetweentwoactivitypeaksinthespectrum.Byone-dimensionalhybridsimulations,theeffectofrelativedriftvelocitiesbetweenprotonsandHe2+onthemagneticspectralsignaturesinthePDLisstudied.Theresultsshowthattherelativedriftvelocityenhancesthedevelopmentofprotoncyclotronwavesanddeclinesthedevelopmentofheliumcyclotronwaves.Theprotoncyclotronwavesarefirstlyexcited,andfollowedbytheexcitationofheliumcyclotronwavesduetotheincreaseintherelativedriftvelocity.Moreover,theboundarybetweentwoactivitypeaksgetsobscure.
简介:Zn_(1-x)Cu_xOthinfilmsweresynthesizedbytheradiofrequency(RF)magnetronsputteringtechniqueusingaZnOtargetcontainingdifferentpiecesofsmallCu-chips.X-raydiffraction(XRD)andscanningelectronmicroscopy(SEM)wereemployedtoanalyzethecrystallineandmicrostructureofthefihn,andX-rayphotoelectronspectroscopy(XPS)wasusedtoestablishthebondingcharacteristicsandoxidationstatesofcopperinsidetheZnOhost.Roomtemperature(RT)ferromagnetismwasobservedintheZn_(1-x)Cu_xOfilmsbyaQuantumDesignsuperconductingquantmninterferencedevice(SQUID)andthesaturationmagneticmomentofthefilmswasfoundtodecreasewiththeincreaseinCucontent.
简介:Vacuumtreatmentandion-beambombardmentaretwomajorprocessesinthelowenergyion-beamimplantation.Toaccuratelystudythecontributionsofthesetwomajorfactorstothebioeffectsseparately,theM_1generationvariationofArabidopsisthalianawithion-beamimplantationandvacuumtreatmentwerecomparedthroughaseriesofkeyplantdevelopmentparametersincludingmorphologicalobservation,biochemicalassayandRAPD(randomamplifiedpolymorphicDNA)analysis.Theresultsshowedthation-beamimplantationhadobviouseffectonalmostalloftheseparameters,andthevacuumtreatmenthadsomeimpactsonseveralmorphologicalparameterssuchastheboltingtimeandthelengthoftheprimarystem.Takingtheresultstogether,theindicationisthatvacuumtreatmenthassomeslightcontributionstothebioeffectsofion-beamimplantationwhileion-beambombardmentitselfisthemajorcreatorofthebioeffects.
简介:Anewrectangularpulsetriggergeneratorhasbeendevelopedwhichcangeneratetwo10kVpulseswitharisetimelessthan1ns,ajitterof0.2nsandawidthofabout10nsand40ns,respectively.Thisgeneratorusestwopolymer-foilswitchesand25ohmBlumleintransmissionlinescomposedoftwo-parallelstandardcoaxialcablesdischargingintotwo50ohmoutputcables.Thepulsewidthandthedelaybetweentwopulsescanbeadjustedbychangingthelengthofthecables.
简介:AnovelfittingprocedureisproposedforabetterdeterminationofH2rovibrationaldistributionfromtheFulcher-abandspectroscopy.WehaverecalculatedthetransitionprobabilitiesandtheresultsshowthattheydeviatefromFranck-Condonapproximationespeciallyforthenon-diagonaltransitions.Wealsocalculatedthecompletesetsofvibrationallyresolvedcrosssectionsforelectronimpactd3∏u-X3∑gtransitionbasedonthesemi-classicalGryzinskitheory.AnexampleofexperimentalstudyconfirmsthatcurrentapproachprovidesatoolforabetterdiagnosticsofH2rovibrationaldistributioninelectronicgroundstate.
简介:采用程序升温氮化的方法制备了钼氮化物催化剂,并用EXAFS方法研究了氮化前后Mo原子的局域配位情况。负载MoO3样品的径向结构函数中有三个峰其中前两个峰对应着最近的Mo-O配位壳层,但是第一个峰与第二个峰的比例比晶体MoO3中的比例大很多,表明分子筛负载的MoO3具有更紧密的结构。氮化以后,Mo2N样品的径向结构函数中有三个峰,对应于一个Mo-N和两个Mo-Mo配位壳层,与面心立方模型符合的很好。根据X射线衍射和EXAFS谱的计算表明,Mo2N中的N原子使Mo-Mo键拉长并削弱。分子筛负载的Mo2N样品具有与非负载Mo2N样品相似的径向结构函数,只是对应于Mo-N壳层的峰较弱,表明负载的MoO3更难氮化。
简介:LocalstructuresofthemolybdenumsulfidespeciesinthesultidedRh-Mo-K/Al2O3catalystswithvariousrhodiumloadingshavebeeninvestigatedbyXAFS.Fromthefittingresults.theMo-Mocoordinationnumberforthesamplefreeofrhodium(ca.3.7)issimilartothatforthecrystallineMoS2,indicatingthatthesupportedsulfidedmolybdenumspeciesmainlypresentaslargepatechesofMoS2-likeslabs.Fortherhodium-modifiedsamples,however,theamplitudesoftheMo-SandMo-Mocoordinationshellsaresharplyreduced,revealingahighdispersionoftheMoS2-likespeciesinthecatalysts,TheschemeofthemicrostructuresofthesulfidedmolybdenumspeciesstabilizedonthealuminasupportisdiscussedbasedupontheanalysisoftheEXAFSdata.
简介:采用XRD、EXAFS技术研究了不同Pd含量的Pd-Mo-K/Al2O3催化剂结构,并关联其合成低碳混合醇性能。结果表明,在氧化态Mo-K/Al2O3催化剂体系中添加Pd后,“K-Mo”物相晶粒变小,分散度提高,说明钯可能和钾钼物种发生了较强的相互作用。经硫化还原处理后,发生了氧硫交换,钼主要以MoS2物种形式存在,其粒度随着Pd含量的增加而明显减小。尺寸的显著变化可能导致MoS2与载体作用形式的改变,从而影响CO加氢催化反应的性能。在硫化态催化剂中,Pd的添加不仅能提高CO加氢合成醇的收率和选择性,而且有利于改善产物的分布。基于以上结果,认为“K-Mo”作用物种和Pd物种均为合成醇的催化活性组份,它们间的相互协同作用使催化剂性能得到显著改善。
简介:采用EXAFS方法研究了经中温等温和低温LN2处理的2mol%Y2O3-ZrO2陶瓷中Zr^4+和Y^3+离子的近邻结构。结果表明,与中温等温试样相比,LN2处理的试样中Zr-O层和Zr-Zr(Y)层的配位数显著减少,平均键长明显缩短;Y-O层配位数减少,Y-Zr(Y)层平均键长伸长;各配位层畸变程度均增大。两个试样的Y-O层配位数均高于Zr-O层配位数,表明点阵中的氧空位倾向于与Zr离子为邻。分析认为,该试样Zr-O配位层中较多的氧空位主要来源于从高温快速冷却时所保留下来的Schottky缺陷,对四方相稳定性和中温相变具有重要的影响。