Mossbauer nyhuv: cov nyhuv ntawm lub foundations thiab nws tseem ceeb

Cov tsab xov xwm hais txog dab tsi lub Mossbauer nyhuv. Tsis tas li ntawd qhia tawm tswv yim xws li quantum zog nyob rau hauv ib tug atom thiab ib tug atomic nucleus, khoom thiab collective quasiparticle therein.

lej lom zem

Ib tug txhob nyob rau hauv physics uas tshwm sim nyob rau hauv thawj xyoo caum ntawm lub thib nees nkaum xyoo pua, zaum demanded loj paub nyob rau hauv kev kawm lej. Muaj ntau discoveries tau rho, li ntawd, yuav hais lus, nyob rau ntxeev ntawm tus cwj mem: thaum xub thawj lawv xam raws thiab ces nyob rau hauv kev xyaum.

Piv txwv li, lub neej ntawm gravitational tsis kwv yees los ntawm Einstein nyob rau hauv 1910, twb tau kom paub meej tias experimentally xwb nyob rau hauv 2016. Lub merger ntawm ob neutron hnub qub tau tsim tshee qhov chaw uas terrestrial physics ntes tau thiab tsau los ntawm qhib lub era ntawm gravitational ntsuam nyob rau hauv qhov kev kawm ntawm tib neeg. Tsis muaj lub zem lub ntiajteb txawj nqus hais nyob ntawm no: namely rau tej cov kev tshawb fawb yog lub Mossbauer nyhuv nqi. Tab sis qhov no yog lub kos es txoj cai. Feem ntau cov feem ntau, theorists thiab experimenters tsuj lwm tus txoj kev heels, ib txoj kev tshawb muab ntxiv rau qhov yuav tsum tau rau nws zauv hauj lwm, thiab kev phiv xaus ua lub assumption tshiab, tseem tsis tau tau txais dependencies. Mössbauer nyhuv yog ib tug ntawm xws phenomena. Tej "sab" phenomenon yog lub assumption thiab lub Max Planck qhia nyob rau thaum xaus ntawm 1900. Nws hais tias nyob rau hauv lub ntiaj teb no ntawm electrons thiab atomic nuclei, tag nrho cov ntau tsuas nqa tau discrete qhov tseem ceeb, uas yog quantized. Thiab, nyob rau hauv nws tus kheej lub tswv yim, nws yog ib tug lej ua kom yuam kev, uas ua kev xam yooj yim. Txog rau thaum xaus ntawm nws lub neej nws ntseeg hais tias lub quantum, los yog qhov tsawg tshaj plaws tau feem ntawm, piv txwv li, lub teeb - tsuas yog tsim txoj kev uas yuav piav qhia txog, tsis nqa ib tug loj lub cev kev txiav txim zoo.

Lub quantum ntiaj teb no

Txawm li cas los, lwm yam kws tshawb fawb xav nyob rau hauv ib tug txaus piav qhia txog dab tsi yog tshwm sim nyob rau hauv lub scale ntawm atoms, suav hais tias lub peev xwm ntawm xws li ib tug xaus, thiab coj nws khuv xim hais tias txhua yam yog quantized. Lub electrons nyob ib ncig ntawm lub nucleus yuav tsuas nyob tau rau tej yam orbits nuclei lawv tus kheej muaj peev xwm tsuas muaj kev zog. Tsis mus therebetween, nuclei tsim gamma rays. Mossbauer nyhuv cav hais tias qhov kev txiav txim yuav tsum tsim ib hom ntawm rov qab, tab sis qhov no tsis tshwm sim. Nyob rau hauv Feem ntau, tag nrho cov ntau uas piav qhia txog tus cwj pwm ntawm cov nanoworld no yuav quantization - uas yog discrete. Tab sis tsis txhob hnov qab tias lub zog uas nyob rau hauv lub macrocosm yog qhia raws li cov khoom ntawm tus nqi ntawm loj rau elementary hais yog ib yam dab tsi fundamentally sib txawv, uas txhais tau tias nws, dhau lawm, yog quantized. Yog li ntawd hais tias science daim ntawv qhia nyob rau hauv uas lub Maks plank muab nws nto moo mis uas muaj tus nqi ntawm h, los yog tsawg heev nyhuv, qhib ib tug tshiab era. Qhov no yog lub era ntawm quantum physics. Mossbauer nyhuv, txhais, uas tom qab muab rau no tshwm sim, tau ua ib tug ntawm cov tseem ceeb tshaj plaws milestones ntawm science ntawm lub thib nees nkaum caug xyoo.

Tus foundations ntawm cov Mössbauer nyhuv

Raws li peb tau sau tseg saum toj no, lub theoretical cov lus xaus mus tes hauv tes nrog cov xyaum ua tej yam. Ib txhia cov tswv yim cov lus xaus muaj pov thawj nyob rau hauv cov nroj tsuag sau cia "rau lub hauv caug" thiab tawm ntawm seem cov ntaub ntawv. Zaum tau tsis tsuas tso saib cov mis, tab sis kuj muab cov hwj, txiav lub Rooj Tswjhwm Saib mus ua hauj lwm nrog hlau thiab sib sau ua ke rau hauv lub installation. Ntawm cov hoob kawm, lub taub hau ntawm lub chaw soj nstuam tsuas tshab xyuas lub tau ntawm lawv tej pawg ntseeg. Txawm li cas los, txhua experimenter yog kuj yog ib tug engineer, raws li cov pab kiag li lawm yog tsim rau tej lub hom phiaj, thiab ncaj qha nyob rau hauv cov kev tshawb fawb cov txheej txheem. Kuv tsis muaj kev zam thiab lub Mossbauer nyhuv. Qhib nws yuav tsis muab qhov chaw, yog hais tias ib tug tawv ncauj doctoral Rudolf Mossbauer tsis tau hloov cov qauv ntawm xab lub txias chav tsev, es tsis txhob ntawm cua sov nws, raws li qhia los ntawm tus thawj saib xyuas ntawm cov kev tshawb fawb.

khoom

Qhov kev tshawb xav, uas peb yuav qhia rau cov txawj nyeem ntawv nyob rau hauv seem no, no mas, tseeb ntawm thawj siab ib muag. Txawm li cas los, raws li yog paub zoo tias, ib qho yooj yim mus yeej ib txwm achieves zoo kawg dag zog. Thiab yog li ntawd peb muaj tam sim no tau qhia nyob rau hauv cov lus yooj yim zoo li cas rau Mossbauer nyhuv rau Dummies cia, ib zaug ua hauj lwm rau tag nrho cov kev kuaj.

Nyob rau hauv lub khoom no feem ntau yog meant ib yam khoom uas nyob rau hauv ib tug crystalline lub xeev. Lub nuclei ntawm atoms nyob rau hauv cov ntaub ntawv no tsim ib tug nruj periodic lattice, whereas lub electrons nyob rau hauv cov zaubmov sau ua ke. Ntawm cov hoob kawm, hlau muaju tsim heev nws yog xim hlau daim ntawv cog lus los ntawm kev uas lub nucleus muaj nyob raws li cais los ntawm generalized electrons. Lub electron huab nyob ntawm nws txoj kev ywj siab kev cai lij choj, tsis hmoog rau tus cwj pwm ntawm tus siv lead ua ntxaij ntoo. Lub muaju uas qhia ntau tsoos ionic thiab covalent bonds, cov electrons ntau zoo mob nrog rau "lawv" nuclei. Tab sis muaj lawv mus tau rau ntawm neighboring ntshav tshaj nyob rau hauv ib tug roj los yog kua.

Khoom txheej zog tsis tau tsuas yog cov tshuaj hais uas yog nyob rau hauv lawv, tab sis kuj cov teeb ntawm lub arrangement ntawm atoms txheeb ze rau txhua tus lwm yam. Nyob rau hauv lub classic piv txwv ntawm ib cov qauv generates mos graphite, thiab rau lwm yam - lub hardest ntuj cov ntaub ntawv uas - pob zeb diamond. Yog li ntawd yog dab tsi hom ntawm kev twb kev txuas, thiab symmetry ntawm lub tsev cell yog ib tug ntau mus rau ib tug txhav lub cev. Lub zog ntawm cov khoom thiab nws yog ib lub qhia tawm ntawm dab tsi lub Mossbauer nyhuv. Nws qhov yog piav raws li nram no: tag nrho cov atoms nyob rau hauv ib tug khoom yog txuam.

collective quasiparticles

Tam sim no xav txog tej yam ib tug txaus loj peb-dimensional lattice. Rau cov qauv tsim ntsev: Na thiab Cl nyob rau hauv lub vertices ntawm lub cubes, ib tug tom qab lwm. Yog hais tias ua cas lob ib tug atom thiab rub nws mus ua txhaum lub npaj qhov chaw ntawm tshuav nyiaj li cas, ua tsaug rau ib tug txaus txhav kev twb kev txuas, tom qab nws rub lub nyob sib ze atoms. Suav qhia tau tias cov kev hloov nyob rau hauv txoj hauj lwm ntawm cov tub ntxhais muaj tsawg kawg yog tej yam teeb meem loj rau cov neeg zej zog ntawm peb kev txiav txim. Qhov no txhais tau tias yog hais tias tus "lob" sodium, ua raws li rub ze tshuaj atoms, sodium atoms nram qab no nws yog ib tug outermost txheej ntawm chlorine. Tej yam ntawm no yog yuav tsum ncua nyob rau hauv tag nrho cov lus qhia. Nws yog feem ntau hais tias tus plaub-thiaj perturbation cov neeg nyob ze yog negligible. Txawm li cas los, lawv yuav tsis pes tsawg.

Thiaj li yog sov ua licas "khob" siv lead ua muaj zog (e.g., xa nws ib tug laser los yog electron nqaj), tus siv lead ua ntxaij ntoo yuav "tsis". Tej collective zog thaum ntau neighboring atoms nyob rau hauv tus siv lead ua ib txhij ua hauj lwm ceev xav tias, e.g., los yog down, hu ua phonons. Muaj rau piav qhia txog dab tsi lub Mossbauer nyhuv rau dummies, peb yuav tsis mus rau hauv cov ntsiab lus thiab cia li qhia rau koj hais tias cov phonons twb pom coj raws li elementary hais. Piv txwv li, lawv lub zog yog quantized, lawv muaj wavelength momentum thiab muaj peev xwm mus nrog txhua lwm yam. Yog li, lub phonons yog hu ua collective quasiparticles. Lawv tus xov tooj thiab zoo tshaj ntawm cov khoom cev yog muab ib tug qauv nyob rau hauv uas lawv tshwm sim. Xam nws yuav ua tau, paub txog qhov luaj li cas, symmetry thiab hom ntawm atoms ntawm lub tsev ntawm tes. Nyob rau tshwm sim ntawm phonon kuj muaj feem xyuam rau qhov ntev thiab hom bonds ntawm lub ions nyob rau hauv lub siv lead ua ntxaij ntoo.

band kev tshawb xav

Txij li thaum cov khoom tshab xyuas tag nrho nws cov electrons, thiab cov orbitals (thiab li no lawv lub zog) yuav tsum tau generalized. Ua ntej, peb yuav tsum nco ntsoov hais tias cov electrons mus rau qhov no hauv chav kawm ntawv ntawm hais hu ua fermions. Fermi, Dirac thiab Pauli ua ke pom tias nyob rau hauv ib lub xeev tej zaum yuav nyob rau hauv lub cev, tsuas yog ib tug xws particle. Yog hais tias peb rov qab mus rau cov piv txwv ntawm cov ntsev, txhua siv lead ua, uas peb nphoo kua zaub los yog nqaij, muaj ib qho zoo kawg npaum li cas ntawm sodium thiab chloride ions. Thiab txhua yam uas lawv muaj tib lub xov tooj ntawm electrons, uas tig rau tib yam orbits. Yuav ua li cas yuav hais tias yuav? Ib tug khoom tawm ntawm qhov teeb meem no raws li nram no: lub zog ntawm txhua electron orbiting ib ncig ntawm lub keeb, ib tug me ntsis txawv los ntawm lwm yam zog electrons teej tug mus rau tib lub orbit ntawm lwm atom. Yog li ntawd nws tau: nyob rau hauv lub siv lead ua tshwm sim tsis tshua muaj neeg ntau zog ntau uas txawv los ntawm txhua lwm yam sufficiently me me mus rau tsim ib tug compressed cheeb tsam. Lub perturbations uas paub phonons me me vim hais tias ib tug atom yog hom twg yog tsis muaj zog heev. Txhua yam uas tseem ceeb yog ib lub collective tsab ntawv tsa suab raws li ib tug tag nrho. Yog li ntawd, lub phonon zog, raws li nws twb "yaj" nyob rau hauv lub cheeb tsam ntawm lub zog. Raws li qhov no thiab lub Mossbauer nyhuv.

electromagnetic scale

Lub zog ntawm them hais yog nrog los ntawm ib tug electromagnetic teb. Qhov tseeb txo nws hwj, piv txwv li, cov lus nug ntawm yog vim li cas ib tug ntiaj chaw thiab satellites tau lawv, thaum lwm tus neeg - yog tsis. Electromagnetic vuag yuav subdivided rau hauv cov chav kawm ntawv raws li lawv zaus thiab yog li ntawd lub zog. Cov ob yam ntxwv yog interconnected thiab nyob ntawm seb lub wavelength. Yuav ua li cas yog lub Mossbauer nyhuv yuav tsuas luv luv, muab hais tias tus nyeem ntawv to taub qhov twg electromagnetic scale yog nyob gamma tawg. Yog li ntawd, qhib tau lub airwaves scale. Raws txwv lawv wavelength - qhov ntev ntug. Txawm li cas los, lub zog ntawm xws tawg yuav yog li me me hais tias nws yog tsis yooj yim sua mus sau npe. Me ntsis siab dua zaus nyob rau hauv lub terahertz tawg. Txawm li cas los, nws yog, thiab lub xov tooj cua tsis muaj cai nyob rau hauv heev tej yam kev mob: inhibition ntawm electrons nyob rau hauv ib tug sib nqus teb, FLEXURAL deeg ntawm polymers, lub zog ntawm excitons nyob rau hauv cov khoom. Ntau ntshiab tom ntej no yog ib feem ntawm lub electromagnetic spectrum - lub infrared tawg. Nws hloov lub zog nyob rau hauv daim ntawv ntawm tshav kub. Txawm siab zog ntawm pom lub teeb. Hais tias ib feem ntawm lub spectrum hais tias tus tib neeg qhov muag pom yog heev me me piv rau tag nrho teev.

Liab lub teeb muaj qhov qis zog, thiab ntshav - lub siab tshaj plaws. Nyob rau hauv no kev twb kev txuas, nws yog lub npe hu paradox: qhov ntau dej txias yog qhia nyob rau hauv xiav, uas nws lub zog yog siab tshaj uas ntawm lub teeb liab. Tom qab hais tias cov ultraviolet feem ntawm lub electromagnetic scale twb muaj ib tug txaus siab zaus mus txeem rau hauv ib lub khoom. Txawm tias muaj tseeb hais tias cov neeg, ib yam li lwm nyob creatures nyob hauv lub ntiaj teb, tsis txhob pom ultraviolet lub teeb, nws tseem ceeb rau cov hauj lwm ntawm lom kab mob yog enormous. Lub ntsiab qhov chaw ntawm ultraviolet txoj kev tshawb no yog lub hnub. Ntau dua lub zog thiab lub peev xwm mus txeem ntau yam muaj X-ray. Yog qhov uas cov xws tawg yog lub deceleration ntawm electrons nyob rau hauv lub electromagnetic teb. Lub electrons yuav tau ob leeg khi, i.e. yuav atoms thiab dawb. Cov kev kho mob pab kiag li lawm yog pab kiag li lawm los ntawm free electrons. Thaum kawg, lub toughest thiab feem ntau luv luv-yoj yog gamma tawg.

X-rays thiab gamma

Mossbauer nyhuv thiab nws daim ntawv thov nyob rau hauv physics thiab engineering xav tau kev pab kom paub qhov txawv ntawm gamma rays thiab X-rays. Los ntawm cov theem ntawm lub zog thiab, raws li, lub wavelength lawv yog nyob rau hauv ib tug heev ntau yam ntawm sib tshooj. Uas yog, yog ib tug gamma thiab X-rays nrog ib tug wavelength ntawm 5 picometres. Txawv txoj kev rau lawv cov kev npaj. Raws li tau piav saum toj no, cov X-tawg tshwm sim thaum lub deceleration ntawm electrons. Ntxiv mus, nyob rau hauv ib co dab (xws li nuclear) disappears electron ntawm lub puab plhaub txaus hnyav atom, xws li uranium. Txawm li cas los, lwm yam electrons yuav siv nws qhov chaw. Tej zaus, thiab ua ib qhov chaw ntawm X-rays. Gamma rays yog lub txiaj ntsim ntawm lub nucleus hlos los ntawm ib tug ntau dua pog xeev. Qhov no tawg muaj ib tug high tob tob muaj peev xwm thiab ionizes atoms uas ua num ua ke. Wherein thaum lub gamma ray tsoo nrog lub nucleus ntawm ib tug atom, muaj yuav tsum yog ib tug thiaj li hu ua kickback. Txawm li cas los, nyob rau hauv kev xyaum nws muab tawm hais tias tus sis ntawm gamma rays nrog lub nucleus ntawm ib tug atom teej tug mus rau lub txhav lub cev, tej yam uas ploj lawm. Qhov no yog piav los ntawm qhov tseeb hais tias ntxiv zog, raws li nws twb "smeared" los ntawm hluav taws xob bands ntawm tus siv lead ua, tsim ib phonon.

isotopes

Mossbauer nyhuv thiab nws daim ntawv thov yog zoo txog mus rau ib tug tsab fact: lub phenomenon tsis ua rau tag nrho cov tshuaj hais ntawm lub periodic rooj. Ntxiv mus, nws yog tseem ceeb tsuas yog rau ib co tshuaj isotopes. Yog hais tias tus nyeem ntawv yog mam li nco dheev tsis nco qab lawm yog dab tsi isotopes rov qab. Nws yog lub npe hu hais tias txhua atom yog electrically nruab nrab. Qhov no txhais tau tias nyob rau hauv lub nucleus ntawm zoo protons ntau li ntau nyob rau hauv lub electron plhaub. Txawm li cas los, cov tub ntxhais kuj muaj ib tug neutron, particle tsis them nyiaj. Yog hais tias koj hloov tus xov tooj nyob rau hauv lub nucleus, hluav taws xob neutrality yog tsis tau ua txhaum, tab sis lub thaj chaw ntawm lub atom hloov me ntsis. Nyob rau hauv tas li ntawd, nws tshwm sim hais tias lub cev ntas isotope yog tej thiab yog nws lwj, thaum zoo tib yam teeb meem yog heev ruaj khov. Heev ib daim ntawv teev kev ua vaj tse ntsiab thiab lawv isotopes, uas yog tsiag ntawv los ntawm Mossbauer nyhuv. Nov ntawm ⁵⁷ Fe, piv txwv li, feem ntau yog ntseeg los ntawm no phenomenon.

Kev siv ntawm quantum los

Ua cov kev, uas yog paub tseeb hais tias los ntawm ib tug los yog lwm yam kev xav hais txog cov me ntiaj teb no, nws yog feem ntau tsis yooj yim. Nyob rau hauv tas li ntawd, nws yog paub tsis meej dab tsi pab yuav coj cov nyhuv tib yam Mossbauer? Kev siv ntawm nws, txawm li cas los, yog dav txaus. Kev tshawb nrhiav ntawm thaj chaw ntawm crystalline cov ntaub ntawv, amorphous khib nyiab thiab finely comminuted hmoov tshwm sim, xws li ntawm no quantum phenomenon. Tej ntaub ntawv yuav tsum tau nyob rau hauv haum nyob deb ntawm txoj kev xyaum khej (theoretical physics), thiab nyob rau hauv zoo heev tus txiv neej disciplines - xws li tshuaj. Yog li, lub Mossbauer nyhuv thiab nws siv yuav tsum tau yuav tau li ib qho piv txwv ntawm theoretical discovery, uas coj ib tug ntau ntawm cov kev pab, txawm nyob rau hauv lub neej txhua hnub.