简介:CaF2:Ho3+/Yb3+nano-particleswithintensegreenup-conversion(UC)luminescencearesuccessfullysynthesizedviaafacilehydrothermalapproachbyusingNH4FasthefluoridesourceandNa2EDTAasachelatingreagent.PowderXraydiffraction(XRD),transmissionelectronmicroscopy(TEM),fieldemissionscanningelectronmicroscopy(FE-SEM),andUCemissionspectraareusedtocharacterizethestructures,shapes,andluminescentpropertiesofthesamples.TheeffectsfromfluoridesourcesandchelatingreagentsontheformationsofCaF2nano-particlesareinvestigated,andtheformationprocessisalsodeduced.Undertheexcitationofa980-nmlaserdiode,thesampleseachshowagreenup-conversionemissioncenteredat540nmcorrespondingtothe5S2/5F4→5I8transitionsofHo3+.Moreover,theUCmechanismsofHo3+/Yb3+co-dopedCaF2nano-particlesarealsodiscussed.
简介:3-(2-Hydroxyphenyl)-6-(4-nitrophenyl)-7H-1,2,4-triazolo[3,4-b][1,3,4]thiadiazine,C16H11N5O3S,waspreparedbythecyclizationof3-(2-hydroxyphenyl)-4-amino-5-mercapto-1,2,4-triazolewith2-bromo-4-nitroacetophenone.Thecompoundwascharacterizedbymeansofelementalanalysis,IR,1HNMR,13CNMR,massspectrometry,andX-raydiffraction.ThecompoundcrystallizesinamonoclinicsystemwithspacegroupCc,a=2.1853(4)nm,b=2.1192(5)nm,c=1.3526(3)nm,β=95.21(2)°,V=6.238(2)nm3,Dcalcd.=1.505Mg/m3,Z=16,F(000)=2916,R1=0.0501,wR2=0.0427.Acomparisonbetweenthecrystalstructuresof1,2,4-triazolo[3,4-b][1,3,4]thiadiazineand1,2,4-triazolo[3,4-b][1,3,4]thiadiazolewasmadeinthestructuralview.Atwo-dimensionalnetworkisformedbyhydrogenbondsandπ-πstackinginteractions.
简介:利用TCAD仿真技术,研究了电离总剂量辐射陷阱电荷对0.18μmN沟道MOSFET转移特性的影响.构建了0.18μmN沟道MOSFET的三维仿真结构,获得了在电离总剂量(totalionizingdose,TID)效应影响下,负栅压偏置时器件中电流密度的分布情况.分析了器件浅槽隔离层(shallowtrenchisolation,STI)中氧化物陷阱电荷和界面态陷阱电荷对器件泄漏电流的影响.仿真计算了N-MOSFET的转移特性,仿真结果与辐照试验结果受辐照影响的趋势基本一致,为深亚微米MOS器件的总剂量辐射效应的损伤机制提供了一种分析手段.
简介:Atheoreticaldesignispresentedfora1×Mwavelength-selectiveswitch(WSS)thatroutesanyoneofNincomingwavelengthsignalstoanyoneofMoutputports.Thisplanaron-chipdevicecomprisesofa1×Ndemultiplexer,agroupofNswitching'trees'actuatedbyelectro-opticalorthermo-opticalmeans,andanM-foldsetofN×1multiplexers.Treesutilize1×2switches.TheWSSinsertionlossisproportionalto(log2(M+N+1))Alongwithcrosstalkfromtrees,crosstalkispresentateachcross-illuminatedwaveguideintersectionwithintheWSS,andthereareatmostN-1suchcrossingsperpath.TheselossandcrosstalkpropertieswilllikelyplaceapracticallimitofN=M=16upontheWSSsize.Byconstrainingthe1×2switchingenergyto1fJ∕bit,wefindthatresonant,narrowband1×2switchesarerequired.The1×2devicesproposedherearenanobeamMach–Zehndersandasymmetriccontra-directionalcouplerswithgratingassistance.
简介:<正>Inthefifties.Calderonestablishedaformalrelationbetweensvmbolandkerneldistribu-tion,butitisdifficulttoestablishanintrinsicrelation.TheCalderon-Zygmund(C-Z)schoolstudiedrheC-Zoperators,andHormander.KohnandNirenberg,etal.studiedthesymbolicoperators.HereweapplyarefinementoftheLittlewood-Paley(L-P)decomposition,analyseundernewwaveletbases.tocharacterizebothsymbolicoperatorsspacesOpS1,δmandkerneldistributionsspaceswithotherspacescomposedofsomeahnostdiagonalmatrices.thengetanisometricbetweenOpS1,δmandkerneldistri-butionspaces
简介:主反射镜的口径大小与结构形式在极大程度上决定了空间望远镜的技术难度与经济成本。为了实现更高的空间分辨率与更强的信息收集能力,各国研制的空间望远镜主反射镜的口径朝着越来越大的趋势发展,从“哈勃空间望远镜”(HST)的2.4m,到“新世界观测者空间望远镜”(NWO)的4m,甚至到“先进技术大口径空间望远镜”(ATLAST)的8m,无不体现了对超大口径空间观测能力的追求。而单块式主镜凭借其支撑技术的可靠性与经济性,正成为超大口径空间望远镜的首选。通过对国外研制的超大口径空间望远镜的论述与分析,探讨了目前空间望远镜中超大口径主反射镜的关键技术与发展方向。针对目前国内运载能力与光学制造加工能力的极限,提出了建造基于3.5m口径主镜的空间望远镜设想。
简介:Amolybdenumdisulfide(MoS2)saturableabsorberwasfabricatedbythermallydecomposingtheammoniumthiomolybdate.ByusingtheMoS2absorber,acompactdiode-pumpedpassivelyQ-switchedTm:GdVO4laserhasbeendemonstrated.AstableQ-switchedlaserwithrepetitionratesfrom25.58to48.09kHzwasachieved.Maximumaverageoutputpowerwas100mWwiththeshortestpulsedurationof0.8μs.Maximumpulseenergyis2.08μJatcenterof1902nm.
简介:Themonomericcobalt-phosphite-thiolatocomplex[Co(mpt)2{P(OCH3)3}2]BF4(Hmpt=2-mercaptothiazoline)hasbeenpreparedandcharacterizedbyX-raycrystallography.ThecomplexcrystallizesinthemonoclinicspacegroupC2/cwitha=0.8078(5),b=2.6020(18),c=1.2191(7)nm,β=99.38(1)°,V=2.528(3)nm3,andZ=4.Thestructurecomprisesdiscretecations[Co(mpt)2{P(OCH3)3}2.]+andanionsBF4-,inwhichthecobalt(Ⅲ)atomiscoordinatedtotwochelatempt-andtwoas-orientedmonodentateP(OCH3)3ligandsinahighlydistortedoctahedralgeometry.ThemostdistortedanglesareS(2)-Co(1)-S(2a)of162.23(10)°andN(1)-Co(1)-S(2)of71.47(13)°,thelatteriscausedbythegeometricconstraintofthebidentateligandmpt-.CyclicvoltammetryhasbeenusedtostudytheelectrochemicalbehaviorofthetitlecomplexontheRelectrodeinMeCNsolutionwith0.1mol·L-1ofBun4NBF4aselectrolyte.TheresultsindicatethatthetitlecomplexisunstableinMeCN.
简介:采用CBS-QB3方法构建了丙烯酸甲酯(CH_2=CHCOOCH_3)与O_3反应体系的势能剖面并在此基础上利用经典过渡态理论(TST)和Wigner矫正模型计算了标题反应在200K~1200K温度区间内的速率常数kTST/W.研究结果表明,CH_2=CHCOOCH)3与O)3反应首先经过渡态生成一个稳定的五元环中间体,然后按断键位置不同,分别生成产物P1(CH_3OCOCHO+CH_2O_2)和P2(CH)3OCOCHOO+HCHO).此外,速率常数结果显示,在计算温度范围内,标题反应速率常数呈正温度系数效应.294K时,CH_2=CHCOOCH_3与O_3反应速率常数为1.76×10^(-18)cm^3·molecule^(-1)·s^(-1),与所测实验值(0.95±0.07)×10^(-18)cm^3·molecule^(-1)·s^(-1)非常接近.