Cov pulses Attosecond qhia txog cov lus zais ntawm kev ncua sijhawm

Cov pulses Attosecondqhia cov lus zais ntawm kev ncua sijhawm
Cov kws tshawb fawb hauv Tebchaws Meskas, nrog kev pab los ntawm attosecond pulses, tau qhia cov ntaub ntawv tshiab txog qhovcov nyhuv photoelectric: tuskev xa tawm photoelectricqhov kev ncua sij hawm yog txog li 700 attoseconds, ntev dua li qhov xav tau yav dhau los. Cov kev tshawb fawb tshiab no sib tw cov qauv kev xav uas twb muaj lawm thiab pab txhawb rau kev nkag siab tob dua txog kev sib cuam tshuam ntawm cov electrons, ua rau muaj kev txhim kho cov thev naus laus zis xws li semiconductors thiab cov hnub ci hlwb.
Qhov teebmeem photoelectric yog hais txog qhov xwm txheej uas thaum lub teeb ci ntsa iab rau ntawm lub molecule lossis atom ntawm qhov chaw hlau, lub photon cuam tshuam nrog lub molecule lossis atom thiab tso tawm cov electrons. Qhov teebmeem no tsis yog tsuas yog ib qho ntawm cov hauv paus tseem ceeb ntawm quantum mechanics, tab sis kuj muaj kev cuam tshuam loj heev rau niaj hnub physics, chemistry thiab cov ntaub ntawv science. Txawm li cas los xij, hauv daim teb no, lub sijhawm hu ua photoemission qeeb tau yog ib qho kev sib cav sib ceg, thiab ntau yam qauv theoretical tau piav qhia nws rau ntau qib, tab sis tsis muaj kev pom zoo sib koom ua ke tau tsim.
Raws li thaj chaw ntawm kev tshawb fawb attosecond tau zoo dua qub nyob rau xyoo tas los no, cov cuab yeej tshiab no muab txoj hauv kev tsis tau muaj dua los tshawb nrhiav lub ntiaj teb me me. Los ntawm kev ntsuas qhov xwm txheej uas tshwm sim ntawm lub sijhawm luv luv heev, cov kws tshawb fawb muaj peev xwm tau txais cov ntaub ntawv ntxiv txog kev coj cwj pwm ntawm cov khoom me me. Hauv kev tshawb fawb tshiab, lawv tau siv cov duab X-ray siab uas tsim los ntawm lub teeb ci ntsa iab ntawm Stanford Linac Center (SLAC), uas kav ntev tsuas yog ib billionth ntawm ib pliag (attosecond), los ua kom cov electrons tseem ceeb thiab "kick" tawm ntawm lub molecule excited.
Yuav kom tshuaj xyuas ntxiv txog cov kev taw qhia ntawm cov electrons uas tau tso tawm no, lawv siv cov kev tshoov siab ib leegcov laser pulseslos ntsuas lub sijhawm tso tawm ntawm cov electrons hauv ntau qhov kev taw qhia. Txoj kev no tso cai rau lawv kom suav qhov sib txawv tseem ceeb ntawm cov sijhawm sib txawv los ntawm kev sib cuam tshuam ntawm cov electrons, lees paub tias qhov kev ncua sijhawm tuaj yeem ncav cuag 700 attoseconds. Nws yog ib qho tsim nyog sau cia tias qhov kev tshawb pom no tsis yog tsuas yog lees paub qee qhov kev xav yav dhau los, tab sis kuj tsa cov lus nug tshiab, ua rau cov kev xav tseem ceeb yuav tsum tau rov kuaj xyuas thiab kho dua tshiab.
Ntxiv mus, txoj kev tshawb fawb no qhia txog qhov tseem ceeb ntawm kev ntsuas thiab txhais cov sijhawm qeeb no, uas yog qhov tseem ceeb rau kev nkag siab txog cov txiaj ntsig ntawm kev sim. Hauv cov protein crystallography, kev thaij duab kho mob, thiab lwm yam kev siv tseem ceeb uas cuam tshuam nrog kev sib cuam tshuam ntawm X-rays nrog cov khoom, cov ntaub ntawv no yuav yog lub hauv paus tseem ceeb rau kev ua kom zoo dua cov txheej txheem kev siv tshuab thiab txhim kho qhov zoo ntawm kev thaij duab. Yog li ntawd, pab pawg neeg npaj yuav txuas ntxiv tshawb nrhiav cov khoom siv hluav taws xob ntawm ntau hom molecules kom qhia cov ntaub ntawv tshiab txog tus cwj pwm hluav taws xob hauv cov kab ke nyuaj dua thiab lawv txoj kev sib raug zoo nrog cov qauv molecular, tso lub hauv paus ntaub ntawv ruaj khov dua rau kev txhim kho cov thev naus laus zis cuam tshuam yav tom ntej.