光對材料作用：若干物理現(xiàn)象

ThePhotoelectricEffectIfabeamoflightispointedatthenegativeendofapairofchargedplates,acurrentflowismeasured.Acurrentissimplyaflowofelectronsinametal,suchasawire.Thus,thebeamoflightmustbeliberatingelectronsfromonemetalplate,whichareattractedtotheotherplatebyelectrostaticforces.Thisresultsinacurrentflow.

PhotoelectricEffectEinsteinsuccessfulexplainedthephotoelectriceffectwithinthecontextofthenewphysicsofthetime,quantumphysics.PhotoelectricEffectEnergyofphoton=Energyneededtoremoveanelectron+Kineticenergyoftheemittedelectron

hf=hfo+1/2mv2=?+Ekh-Planck'sconstant

f0-thresholdfrequencyforthephotoelectriceffecttooccur

?-workfunction,orminimumenergyrequiredtoremoveelectronfromatomicbinding

Ek-maximumkineticenergyobserved

PhotoelectricSensorsphotomultipliertubes(PMTs)PHOTOVOLTAGEEFFECTHowequilibriumisattainedbetweentwosurfaceswhentheyareplacedinexternalelectricalcontact.PHOTOVOLTAGEEFFECTThesurfacefermi-levelofthesemiconductorshiftsduringillumination.Inthiscasethesemiconductorisapnjunctionandweobtaintheopencircuitvoltage.PHOTOVOLTAGEEFFECTTheoxideand/orsemiconductor-oxideinterfacechargesupduringillumination.Thisaltersthethresholdvoltageasmeasuredbytheprobe.Thesechangescanbequitelarge:upto0.5V.Thesemiconductorinterfacecanbeverysensitivetoevenlowlevelsofilluminationofevenafewlux.SolarCellSolarCellNaturalDye-SensitizedNanocrystallineSolarCellPhotoinducedelectronsPhotosensitiveVaristor

PhotocatalysisPhotocatalysisPhotocatalysis1TiO2+2hν2e-+2h+H2O+2h+

2H++?

O2+

TiO22e-+

2H+

H2淨反應(yīng)：

H2O+2hνH2+?

O2PhotocatalysisPhotoinducedchargetransferPhotoinducedphasetransitionPhotoinduced

Desorption

PhotoinducedDesorptionPhotochromicsPhotochromicsinLC討論課安排1、光學玻璃（王盼曉，岳躍平）

玻璃的結(jié)構(gòu)與光學性質(zhì)；光纖材料及其制備；光波導(dǎo)及其制備；光敏玻璃及其制備。2、光學晶體（殷海波，張劍）

晶體光學性質(zhì)；激光晶體；非線性光學晶體；光折變晶體；聲光晶體；閃爍晶體；光學晶體的制備。

3、有機（高分子）光電材料（姜明，王立晟）

有機物的光學性質(zhì)；有機光敏材料；有機電致發(fā)光材料；有機非線性光學材料；有機光導(dǎo)材料；有機光學材料的制備。4、光學陶瓷（蔣方丹，王婷）陶瓷的光學性質(zhì)；透明光學陶瓷及其制備；無機發(fā)光材料及其制備；多孔太陽能電池材料及其制備。