简介：WeestablishasystemtomeasurethefunctionalabsorptioncrosssectionofphotosystemII(PSII)(σPSII)andmaximumquantumyieldofphotochemistryinPSII(Fv/Fm).Thesystemutilizesasequenceofhighfrequencyexcitationflashesatmicrosecondintervalstoinduceamicrosecond-levelfluorescenceyieldcurve.ParametersσPSIIandFv/Fmarecalculatedbyfittingthecurveusingnonlinearregression.Experimentalresultsshowthattherelativestandarddeviation(RSD)ofthesystemislessthan3%,andthecorrelationcoefficientofFv/Fmvaluesmeasuredbythissystemandthosemeasuredbypulseamplitudemodulationmethodis0.950.

简介：Aterahertzexcitationsourcebasedonadual-lateral-modedistributedBraggreflector(DBR)laserworkinginthe1.5μmrangeisexperimentallydemonstrated.Byoptimizingthewidthoftheridgewaveguide,thefundamentalandthefirst-orderlateralmodesareobtainedfromthelaser.Themodespacingbetweenthetwomodesis9.68nm,correspondingtoabeatsignalof1.21THz.BytuningthebiascurrentsofthephaseandDBRsections,thewavelengthsofthetwomodescanbetunedby2nm,withasmallstrengthdifference(<5dB)andalargeside-modesuppressionratio(SMSR>45dB).

简介：Weprovidethefirstdemonstrationofpureredemissioninthevisiblelightregionviathree-photonexcitationinmonodisperseNa_3ZrF_7:Ernanoparticles(NPs)byusingalaseroperatinginthetelecommunicationband.NPsof~22nmindiameteraresynthesizedat260°Cbythethermaldecompositionmethod.TheexperimentalresultsrevealthattheNa_3ZrF_7:ErNPsexhibitpureredemissioninthevisibleregionunder1480nmlaserexcitation,andtheemissionintensityissignificantlyinfluencedbytheEr~(3+)ionconcentration.Thedecaytimesofthe~4S_(3∕2)→~4F_(15∕2)and~4F_(9∕2)→~4F_(15∕2)transitionsoftheEr~(3+)ionsat540and655nm,respectively,arereducedbyincreasingtheEr~(3+)ionconcentrationintheNa_3ZrF_7:ErNPs.Thesuppressedemissionintensityresultfromthedefect-relatedquenchingeffect:whentrivalentEr~(3+)ionsreplactetravalentZr~(4+)ions,extraNationsandFvacanciesareformedtore-balancethechargeintheNa_3ZrF_7matrix.TheemissioncoloroftheNa_3ZrF_7:ErNPsisrelatedtothecrossrelaxationbetweenEr~(3+)ions.Theseresultsprovideanimportantsteptowardmoreeffectivebiologicalimagingandphotodynamictherapybyminimizingthescatteringoftheexcitationlightandincreasingthepenetrationdepth.