简介:为强子的激发QCD的模型预言让比夸克反夸克介子和原来的quark-parton的三夸克的baryons更复杂的结构当模特儿的异国情调的强子的一个分类。这些包括pentaquarkbaryons,六夸克的H-dibaryon,和tetraquark,混血儿和glueball介子。尽管有广泛的试验性的搜索,任何这些异国情调的配置的不含糊的候选人都没被识别。在另一方面,很多个介子说,似乎是一个质子反质子界限状态的,和包含任何一个charmed-anticharmed夸克的其它配对或bottom-antibottom夸克配对,最近被发现了那也不适合进夸克反夸克介子图画也不匹配启发QCD的exotics的期望的性质。这里,我简短为H-dibaryon从最近的搜索考察结果,并且讨论最新发现的状态的一些性质质子反质子状态和所谓的XYZ介子--并且为常规夸克反夸克介子和预言的QCD异国情调的状态把他们与期望作比较。
简介:TheRamanspectraofthenaturalendmembersofthegarnet-groupminerals,whichincludepyrope,almandineandspessariteofFe-Algarnetseriesandgrossularite,andraditeanduvaroviteofCa-Fegarnetseries,havebeenstrdied.MeasuredRamanspectraofthesemineralsarereasonablyandqualitativelyassignedtotheinternalmodes,translationalandrotatorymodesofSiO4tetrahedra,aswellasthetranslationalmotionofbivalentcationsintheXsite.ThestretchandrotatoryA1gmodesfortheFe-AlgarnetseriesshowobviousRamanshiftsascomparedwiththosefortheCa-Fegarnetseries,owingtothecationsresidingintheXsiteconnectedwithSiO4tetrahedrabysharingthetwoedges.TheRamanshiftsofallmemberswithineitheroftheseriesareattributedmainlytothepropertiesofcationsintheXsitefortheFe-AlgarnetseriesandintheYsitefortheCa-Fegarnetseries.
简介:Intramolecularvibrationsoflargemacromoleculesresideintheterahertzrange.Inparticular,proteinvibrationsarecloselyspacedinfrequency,resultinginanearlycontinuousvibrationaldensityofstates.Thisdensityofvibrationsinterfereswiththeidentificationofspecificabsorptionlinesandtheirsubsequentassociationwithspecificfunctionalmotions.Thischallengeiscompoundedwiththeabsorptionbeingdominatedbythesolventandlocalrelaxationalmotions.Astrategyforremovingtheisotropicrelaxationallossandisolatingspecificvibrationsistousealignedsamplesandpolarization-sensitivemeasurements.Here,wedemonstrateatechniquetorapidlyattaintheanisotropicresonantabsorbanceusingterahertztimedomainspectroscopyandaspinningsample.Thetechnique,modulatedorientation-sensitiveterahertzspectroscopy(MOSTS),hasanonzerosignalonlyforanisotropicsamples,asdemonstratedbyacomparisonbetweenasiliconwaferandawiregridpolarizer.Forsucroseandoxalicacidmolecularcrystals,theMOSTSresponseisinagreementwithmodeledresultsfortheintermolecularvibrations.Further,wedemonstratethat,eveninthepresenceofalargerelaxationalbackground,MOSTSisolatesunderlyingvibrationalresonances.
简介:Laser-inducedbreakdownspectroscopy(LIBS)isananalyticaldetectiontechniquebasedonatomicemissionspectroscopytomeasuretheelementalcomposition.LIBShasbeenextensivelystudiedanddevelopedduetothenon-contact,fastresponse,highsensitivity,real-timeandmulti-elementalde-tectionfeatures.ThedevelopmentandapplicationsofLIBStechniqueinAsiaaresummarizedanddiscussedinthisreviewpaper.TheresearchersinAsiaworkondifferentaspectsoftheLIBSstudyinfundamentals,dataprocessingandmodeling,applicationsandinstrumentations.Accordingtothecurrentresearchstatus,thechallenges,opportunitiesandfurtherdevelopmentofLIBStechniqueinAsiaarealsoevaluatedtopromoteLIBSresearchanditsapplications.
简介:Photoconductiveswitcheswerethekeycomponentsthatallowedthegenerationanddetectionofcoherentbroadbandelectromagneticpulsesatterahertzfrequencies,openingthepossibilityforperformingspectroscopyand,therefore,measuringcomplexdielectricpropertiesofmaterialsinthisband,whichwasmostlyunexplored.Inthispaper,wepresentabriefintroductiontotheoperationprinciplesofthesedevices.Subsequently,wepresentareviewofthecurrentstate-of-the-artinthisfieldanddiscussthechallengestobefacedinfuturedevelopmentofthesedevices.
简介:我们由导致激光的故障光谱学(解放)的炸药的察觉上的最近的工作在这份报纸被考察。我们学习了器官的炸药的导致激光的血浆的物理机制,TNT。在单个光子的刺激下面的TNT的解放系列用MATLAB被模仿。碳,氢,氧,和氮对血浆温度的原子排放线紧张的变化也被模仿。我们也调查普通无机的爆炸、黑粉末的解决时间的解放系列,在二种包围气氛,表情和氩,并且发现黑色的O原子排放线SBR的最大的价值搽粉发生在596ns的门延期。我们的工作的另一个焦点在使用象原则部件分析(PCA)和部分最少的广场判别式分析(PLS-DA)那样的chemometic方法把器官的炸药与象塑料那样的器官的材料区分开来上。为分类的一个PLS-DA模型被造。TNT和塑料的七种类型被选择为样品测试模型。试验性的结果证明解放结合了chemometric技术有能力从塑料区别器官的炸药。
简介:正电子歼灭一生光谱学(伙伴)是一种强大的技术在聚合物学习免费体积。ortho电子偶素(o-Ps)的一生,一个电子的一个界限状态和一个正电子,当紧张能被用来描绘毛孔的数字时,能被用来估计毛孔尺寸。(2,6-dimethyl-1,4-phenyleneoxide)(SPPO)根据在在sulfonated的一生系列,半径和部分免费体积的长寿o-Ps部件的价值,poly,有LiCl的不同数量的膜被计算。与LiCl的增加的数量,免费体积半径和部分免费体积第一增加了然后减少,这被发现。在在提取的水里沉浸膜以后,免费体积半径和部分免费体积在膜随着不同的水集中变化了。
简介:TheRamanspectrafromleukemiccellline(HL60)andnormalhumanperipheralbloodmononuclearceils(PBMCs)areobtainedbyconfocalmicro-Ramanspectroscopyusingnear-infraredlaser(785nm)excitation.Thescanningrangeisfrom500to2000cm-1.ThetwoaverageRamanspectraofnormalPBMCsandcarcinomacellshavecleardifferencesbecausetheirstructureandamountofnucleicacid,protein,andothermajormoleculesarechanged.Thespectraarealsocomparedandanalyzedbyprincipalcomponentanalysis(PCA)todemonstratethetwodistinctclustersofnormalandtransformedcells.Thesensitivityofthistechniqueforidentifyingtransformedcellsis100%.更多还原
简介:Theterahertztime-domainspectroscopy(THz-TDS)systemandtherelatedtechnologyandtheapplicationsinCapitalNormalUniversityarepresented.ThemostoftenusedTHz-TDSsystemasaspectroscopicmeasurementsetupinourlabisintroducedindetail,includingtheTHzradiationsource,theTHzdetectionmethodanditsmeasurement,andthecontrolsystem.THzspectraofvariousmaterialsissummarizedanddiscussed.Thesematerialsincludebutnotlimitedtotwokindsoftypicalmatter—theillegaldrugsandexplosives.Thebiologicalmacro-molecules,cosmeticsandfinechemicalmaterials,ediblepigmentsandfoodadditives,homocysteicacidandrelatedcompounds,heavyionsinsoil,Chinesemedicines,tobaccoandcrops,oilandchemicalproducts,carbonnanotubes,superconductors,andvarioussemiconductorsandtheirheterojunctions,arepresented.THzemissionsfromtheInAsandInNsemiconductorssurfacearecompared.THzspectralinvestigationofmetallicmeshstructuresissummarized.Finally,anoutlookofTHzspectroscopicapplicationsisgiven.
简介:Ramanspectroscopyisaversatiletoolwidelyusedforcomprehensiveprobingofcrystalinformation.However,generallywhenappliedinnarrow-band-gapvanderWaalscrystals,itisliabletoforma'bug,'especiallyintransition-metal-dichalcogenides(TMDs).Thatis,severalresonantRaman-scattering(RS)modeswillinevitablyappearintheRamanspectrawithstrongintensity,interferingwiththedesiredsignalofoptical-phononmodes.Here,weproposecross-sectionalpolarizedRamanscatteringcapableofregulatingtheintensityofRSmodesinaccordancewithquasi-sinusoidalrules.Typically,forMoS2andWS2,whenthepolarizationvectorofexcitedlightisalongthecaxisofthecrystal,allRSmodesarenearlycompletely'expunged'fromtheRamanspectra.ThemechanismisthattheabsorptionofmostTMDswithaspacegroupofR3mforthelightpolarizedalongthecaxisisinfinitesimal,thusformingasmallcouplingintensityofelectronicstatesexcitedopticallyandacoustic-phononmodesatpointM,whichinturnrestraintheappearanceofRSmodes.TheregulatingstrategyproposedcanbeappliedtoothervanderWaalscrystalssoastoobtainahighsignal-to-noiseratioRamanspectrum.
简介:Acompactmultipasscellwithlowfringesandhighthermalstabilityisdescribed.Thiscellisformedbytwotwistedcylindricalmirrors.Theopticalparametersaredeterminedbasedontheselectioncriteria,whichincludemirrorfillingefficiency,interferencefringes,andpatternstability.Withapatternof174passes,thiscellgivesa22-mpathlengthinavolumeof0.55L.Theresultsofanabsorptionmeasurementofoxygenat13091.7cm1showthatthefringenoiseislowerthan6.54×104.Themaximumallowedtemperaturechangetokeepthebeamfromexitingis33K,whichindicateshighstabilityagainstthermaldrift.
简介:Ahighlysensitivephotodeflectionspectroscopytechniquewithfemtosecondtimeresolutionhasbeendeveloped.Usingthistechnique,wehavemeasuredaccuratelytheshapeofacousticpulses,whichweregeneratedfromtheultrafastphononemissioninagermaniumplate.Supersonicexpansionofphotoexcitedelectron-holeplasmawasobserved.Thecharacteristicvelocityofplasmadiffusionwasevaluated.Itexceededthelongitudinalsoundvelocityingermaniumbyafactorof4.0.
简介:Terahertz(THz)radiationhasmanypotentialapplicationsincommunication,homelandsecurity,safetyinspection,sensing,andimaging.SpectroscopymaybethemostfundamentalapplicationoftheTHzradiation.ThewidespectrumoftheTHzpulsemakesitmucheasiertoobtainthespectraofmaterialswithmanyabsorptionpeaks,whichrelatedwiththesamplesdirectly.Thisfeature
简介:Terahertz(THz)radiation,whosefrequencyrangesfrom0.1THzto10.0THz,hasrichscience,butlimitedtechnology.Ithaslongbeenconsideredthelastremainingscientificgapintheelectromagneticspectrum.Farfrombeingfullyexploited,itoffersgreatopportunitiesinscience,innovation,newtechnology,andpotentialapplications.