Line spectra - qhov no yog kab tias yog ib qho ntawm cov ntsiab lus tseem ceeb uas tau txiav txim siab hauv chav kawm 8th qib physics hauv ntu optics. Nws yog ib qho tseem ceeb vim tias nws tso cai rau peb nkag siab txog cov qauv atomic, nrog rau siv qhov kev paub no los kawm peb lub Ntiaj Teb. Cia peb xav txog qhov teeb meem no hauv kab lus.
Lub tswvyim ntawm electromagnetic spectra
Ua ntej tshaj, cia peb piav qhia seb tsab xov xwm yuav hais txog dab tsi. Txhua tus paub tias lub hnub ci peb pom yog hluav taws xob nthwv dej. Txhua nthwv dej yog tus cwj pwm los ntawm ob qhov tseem ceeb - nws qhov ntev thiab zaus (nws thib peb, tsis muaj qhov tseem ceeb tsawg dua yog qhov amplitude, uas qhia txog qhov siv hluav taws xob ntau).
Raws li cov hluav taws xob hluav taws xob, ob qho tib si tsis muaj feem cuam tshuam rau hauv kab zauv hauv qab no: λ ν=c, qhov twg cov tsiaj ntawv Greek λ (lambda) thiab ν (nu) feem ntau qhia txog lub wavelength thiab nws zaus, feem, thiab c yog qhov ceev ntawm lub teeb. Txij li thaum tom kawg yog tus nqi tas li rau lub tshuab nqus tsev, qhov ntev thiab zaus ntawm electromagnetic nthwv dej yog inversely proportional rau ib leeg.
Cov electromagnetic spectrum hauv physics tau txaisnpe cov txheej txheem ntawm qhov sib txawv wavelengths (frequencies) uas tau tawm los ntawm cov hluav taws xob sib txuas. Yog hais tias cov khoom absorbs, tab sis tsis emit nthwv dej, ces ib tug hais txog ib tug adsorption los yog absorption spectrum.
Electromagnetic spectra yog dab tsi?
Feem ntau, muaj ob txoj hauv kev rau lawv qhov kev faib tawm:
- Los ntawm hluav taws xob zaus.
- Raws li txoj kev faib tawm zaus.
Peb yuav tsis nyob ntawm qhov kev txiav txim siab ntawm 1 hom kev faib tawm hauv kab lus no. Ntawm no peb tsuas yog hais luv luv tias muaj cov hluav taws xob hluav taws xob ntawm cov zaus siab, uas yog hu ua gamma hluav taws xob (>10 20Hz) thiab X-ray (10 18 -10 19 Hz). Lub ultraviolet spectrum twb qis dua zaus (10 15 -10 17 Hz). Qhov pom lossis kho qhov muag spectrum nyob hauv qhov ntau zaus 10 14Hz, uas sib haum mus rau qhov ntev ntawm 400 µm txog 700 µm (qee tus neeg tuaj yeem pom me ntsis "dav": 380 µm txog 780 µm). Tsawg zaus sib haum mus rau infrared lossis thermal spectrum, nrog rau cov xov tooj cua tsis muaj zog, uas tuaj yeem ua tau ntev li ob peb kilometers.
Tom qab hauv kab lus no, peb yuav ua tib zoo saib qhov thib 2 ntawm kev faib tawm, uas tau sau tseg hauv cov npe saum toj no.
Kab thiab txuas ntxiv emission spectra
Txhua yam khoom, yog tias cua sov, yuav tawm hluav taws xob nthwv dej. Dab tsi zaus thiab wavelengths lawv yuav yog? Cov lus teb rau lo lus nug no nyob ntawm lub xeev ntawm kev sib sau ua ke ntawm cov khoom hauv kev kawm.
Cov kua thiab cov khib nyiab tawm, raws li txoj cai, ib qho kev sib txuas txuas ntxiv ntawm cov zaus, uas yog, qhov sib txawv ntawm lawv yog me me uas peb tuaj yeem tham txog cov hluav taws xob txuas ntxiv. Nyob rau hauv lem, yog hais tias ib tug atomic gas uas tsis tshua muaj siab yog rhuab, nws yuav pib "glow", emitting nruj me ntsis txwv wavelengths. Yog tias tom kawg yog tsim los ntawm cov yeeb yaj kiab yees duab, ces lawv yuav yog cov kab nqaim, txhua tus yog lub luag haujlwm rau qhov tshwj xeeb zaus (wavelength). Yog li ntawd, hom hluav taws xob no hu ua kab emission spectrum.
Nruab nrab ntawm kab thiab txuas ntxiv muaj ib hom nruab nrab ntawm cov spectrum, uas feem ntau emits ib tug molecular es tsis yog ib tug atomic gas. Hom no yog cais pawg, txhua qhov, thaum kuaj xyuas kom meej, muaj cov kab nqaim nyias.
Line absorption spectrum
Txhua yam uas tau hais hauv kab lus dhau los tau hais txog qhov hluav taws xob ntawm nthwv dej los ntawm qhov teeb meem. Tab sis nws kuj muaj absorbency. Cia peb ua qhov kev sim ib txwm muaj: cia peb muab cov roj atomic txias (piv txwv li, argon lossis neon) thiab cia lub teeb dawb ntawm lub teeb ci dhau los ntawm nws. Tom qab ntawd, peb txheeb xyuas lub teeb flux dhau los ntawm cov roj. Nws hloov tawm hais tias yog hais tias qhov flux no yog decomposed rau hauv ib tug neeg zaus (qhov no yuav ua tau siv ib tug prism), ces dub bands tshwm nyob rau hauv lub soj ntsuam tas li spectrum, uas qhia tau hais tias cov frequencies tau absorbed los ntawm cov roj. Hauv qhov no, ib tus hais txog kab nqus spectrum.
In the middle of the XIX century. Tus kws tshawb fawb German hu ua GustavKirchhoff nrhiav tau ib qho khoom muaj txiaj ntsig zoo: nws pom tias qhov chaw uas cov kab dub tshwm nyob rau ntawm cov spectrum tas mus li sib raug raws nraim li cov zaus ntawm cov hluav taws xob ntawm cov khoom muab. Tam sim no, qhov tshwj xeeb no hu ua Kirchhoff txoj cai.
Balmer, Liman thiab Pashen series
Txij li thaum xaus ntawm lub xyoo pua puv 19, cov kws tshawb fawb thoob ntiaj teb tau nrhiav kom nkag siab tias kab hluav taws xob yog dab tsi. Nws tau pom tias txhua lub atom ntawm cov khoom siv tshuaj lom neeg nyob rau hauv ib qho xwm txheej ua pov thawj tib yam emissivity, uas yog, nws emits electromagnetic nthwv dej ntawm qhov tshwj xeeb frequencies.
Thawj qhov kev tshawb fawb ntxaws ntawm qhov teeb meem no tau ua los ntawm Swiss physicist Balmer. Hauv nws qhov kev sim, nws siv hydrogen gas rhuab mus rau qhov kub thiab txias. Txij li thaum hydrogen atom yog qhov yooj yim tshaj plaws ntawm tag nrho cov paub tshuaj, nws yog qhov yooj yim tshaj los kawm txog cov yam ntxwv ntawm cov hluav taws xob hluav taws xob ntawm nws. Balmer tau txais txiaj ntsig zoo heev, uas nws tau sau tseg raws li cov qauv hauv qab no:
1/λ=RH(1/4-1/n2).
Ntawm no λ yog qhov ntev ntawm emission nthwv dej, RH - qee tus nqi tas li, uas rau hydrogen yog sib npaug rau 1, 09710 7 m -1, n yog tus lej pib ntawm 3, piv txwv li 3, 4, 5 thiab lwm yam.
Txhua qhov ntev λ, uas tau los ntawm cov qauv no, pw hauv qhov muag pom pom rau tib neeg. Qhov no series ntawm λ qhov tseem ceeb rau hydrogen yog hu ua spectrumBalmer.
Tom qab ntawd, siv cov cuab yeej tsim nyog, tus kws tshawb fawb Asmeskas Theodore Liman tau tshawb pom lub ultraviolet hydrogen spectrum, uas nws tau piav qhia nrog cov mis zoo ib yam li Balmer's:
1/λ=RH(1/1-1/n2).
Thaum kawg, lwm tus kws tshawb fawb German, Friedrich Paschen, tau txais ib qho qauv rau kev tso tawm ntawm hydrogen hauv cheeb tsam infrared:
1/λ=RH(1/9-1/n2).
Txawm li cas los xij, tsuas yog kev txhim kho ntawm quantum mechanics hauv xyoo 1920 tuaj yeem piav qhia cov qauv no.
Rutherford, Bohr thiab tus qauv atomic
Nyob rau hauv thawj xyoo caum ntawm lub xyoo pua 20th, Ernest Rutherford (British physicist ntawm New Zealand keeb kwm) tau ua ntau yam kev sim los kawm txog radioactivity ntawm ntau yam tshuaj. Ua tsaug rau cov kev tshawb fawb no, thawj tus qauv ntawm lub atom tau yug los. Rutherford ntseeg tias qhov "grain" ntawm cov teeb meem no muaj cov khoom siv hluav taws xob zoo thiab cov hluav taws xob tsis zoo uas tig mus rau hauv nws lub orbits. Coulomb rog piav qhia tias yog vim li cas lub atom "tsis poob sib nrug", thiab centrifugal rog ua rau electrons yog vim li cas lub tom kawg tsis poob rau hauv lub nucleus.
Txhua yam zoo li qhov muaj txiaj ntsig hauv tus qauv no, tsuas yog ib qho tab sis. Qhov tseeb yog tias thaum tsiv mus raws curvilinear trajectory, ib qho khoom siv hluav taws xob yuav tsum tawg cov hluav taws xob hluav taws xob. Tab sis nyob rau hauv cov ntaub ntawv ntawm ib tug ruaj khov atom, cov nyhuv no tsis pom. Tom qab ntawd nws hloov tawm tias tus qauv nws tus kheej tsis raug?
Qhov kev hloov pauv uas tsim nyog tau ua rau nwsLwm physicist yog Dane Niels Bohr. Cov kev hloov kho no tam sim no hu ua nws cov postulates. Bohr tau nthuav tawm ob qhov lus pom zoo rau hauv Rutherford tus qauv:
- electrons txav mus rau hauv qhov chaw nyob ruaj khov hauv lub atom, thaum lawv tsis tawm lossis nqus cov photons;
- cov txheej txheem ntawm hluav taws xob (nqus) tshwm sim tsuas yog thaum lub electron txav ntawm ib lub orbit mus rau lwm qhov.
Dab tsi yog qhov chaw nres tsheb Bohr orbits, peb yuav xav txog hauv kab lus tom ntej.
Quantization ntawm qib zog
Lub voj voog nyob ruaj khov ntawm ib lub tshuab hluav taws xob hauv lub atom, uas Bohr thawj zaug tau hais txog, yog qhov ruaj khov quantum xeev ntawm qhov particle-yoj. Cov xeev no yog tus yam ntxwv los ntawm ib lub zog. Qhov kawg txhais tau hais tias cov hluav taws xob hauv lub atom yog nyob rau hauv qee lub zog "zoo". Nws tuaj yeem nkag mus rau hauv lwm "qhov" yog tias nws tau txais lub zog ntxiv los ntawm sab nraud hauv daim ntawv ntawm photon.
Nyob rau hauv kab nqus thiab emission spectra rau hydrogen, cov qauv uas tau muab los saum toj no, koj tuaj yeem pom tau tias thawj lub ntsiab lus hauv cov hlua yog ib tus lej ntawm daim ntawv 1/m 2, qhov twg m=1, 2, 3.. yog tus lej. Nws qhia txog tus naj npawb ntawm qhov chaw nyob ruaj khov uas cov hluav taws xob hla los ntawm qib siab zog n.
Yuav ua li cas lawv kawm spectra hauv qhov pom tau?
Nws twb tau hais saum toj no tias iav prisms siv rau qhov no. Qhov no yog thawj zaug ua los ntawm Isaac Newton nyob rau hauv 1666, thaum nws decomposed pom lub teeb rau hauv ib txheej xim zaj sawv. Yog vim li casuas cov nyhuv no yog pom nyob rau hauv dependence ntawm lub refractive index ntawm lub wavelength. Piv txwv li, lub teeb xiav (vuag luv) yog refracted ntau zog tshaj lub teeb liab (ntev nthwv dej).
Nco ntsoov tias nyob rau hauv cov ntaub ntawv dav dav, thaum lub beam ntawm electromagnetic nthwv dej txav mus rau hauv ib qho khoom nruab nrab, cov khoom siv hluav taws xob ntau ntawm cov nqaj no yeej ib txwm thim rov qab thiab tawg tawm ntau dua li qhov tsawg zaus. Ib qho piv txwv tseem ceeb yog xim xiav ntawm lub ntuj.
Lens optics thiab pom spectrum
Thaum ua haujlwm nrog lo ntsiab muag, lub hnub ci feem ntau siv. Txij li thaum nws yog ib qho spectrum tsis tu ncua, thaum dhau los ntawm lub lens, nws cov frequencies yog refracted txawv. Yog li ntawd, cov cuab yeej kho qhov muag tsis tuaj yeem khaws tag nrho lub teeb ntawm ib qho chaw, thiab cov duab iridescent tshwm. Cov nyhuv no hu ua chromatic aberration.
Qhov teeb meem qhia ntawm lub lens optics yog ib feem los ntawm kev siv cov iav kho qhov muag ua ke hauv cov cuab yeej tsim nyog (microscopes, telescopes).
