Qhov sib txawv tseem ceeb ntawm Braggs kev xav thiab kev xav zoo ib yam yog qhov kev xav ntawm Braggs muaj lub kaum sab xis ntawm qhov xwm txheej thiab tus tim tswv ntawm kev tawg, whereas, hauv kev xav zoo ib yam, qhov xwm txheej yog qhov cuam tshuam ntawm tib lub kaum sab xis.
Reflection yog hais txog qhov kev hloov pauv ntawm lub wavefront ntawm qhov sib cuam tshuam ntawm ob qhov kev tshaj tawm sib txawv kom lub wavefront rov qab mus rau qhov nruab nrab los ntawm qhov nws pib. Braggs kev xav thiab kev xav zoo ib yam yog ob hom kev xav uas tuaj yeem tshwm sim.
Braggs Reflection yog dab tsi
Braggs xav txog yog qhov tawg ntawm cov hluav taws xob los ntawm cov khoom siv lead ua lattices. Qhov tshwm sim no lub npe los ntawm Bragg txoj cai, uas tau tsim los ntawm Sir W. H. Bragg thiab nws tus tub Sir W. L. Bragg. Bragg txoj cai tseem ceeb heev hauv kev txheeb xyuas cov qauv ntawm cov muaju thiab cov molecules siv X-ray diffraction kev tshawb fawb. Tsis tas li ntawd, txoj cai no piav qhia txog cov txiaj ntsig ntawm kev xav uas tshwm sim ntawm lub ntsej muag siv lead ua thaum lub teeb X-ray raug txhaj rau hauv cov lattice.
Daim duab 01: Dav Hlau Diffraction raws li Bragg Txoj Cai
Raws li Bragg txoj cai, lub kaum sab xis ntawm qhov tshwm sim ntawm lub teeb yog sib npaug rau lub kaum sab xis ntawm kev xav / tawg. Hom kev xav no tshwm sim thaum hluav taws xob nrog lub wavelength uas yog piv rau atomic spacing, yog tawg nyob rau hauv ib txoj kev specular los ntawm atoms ntawm lub crystal system. Ntawm no, cov hluav taws xob muaj kev cuam tshuam zoo ib yam. Yog hais tias lub lattice dav hlau ntawm cov siv lead ua yog sib cais los ntawm ib tug deb "d", lub constructive interference tshwm sim thaum lub tawg pleb vuag nyob rau hauv lub sij hawm vim qhov sib txawv ntawm txoj kev ntev ntawm ob lub nthwv dej yog sib npaug rau ib tug integer ntau ntawm lub wavelength (n). Tom qab ntawd peb tuaj yeem muab txoj cai Braggs raws li hauv qab no:
2d sinθ=nλ
Kev xav zoo li cas?
Kev xav zoo ib yam yog daim iav zoo li kev xav ntawm nthwv dej xws li lub teeb, los ntawm qhov chaw. Tag nrho cov xwm txheej rays yog reflected ntawm tib lub kaum sab xis rau saum npoo ib txwm (nto li ib txwm yog cov kab lus hypothetical uas yog perpendicular rau lub dav hlau saum npoo peb xav txog) thiab qhov xwm txheej, cov lus qhia ib txwm muaj thiab cov lus qhia yog coplanar.
Daim duab 02: Kev xav tsis zoo
Muaj peb qhov tshwm sim tau thaum lub teeb tsoo ntawm qhov chaw. Lawv yog absorption, kis tau tus mob thiab xav txog. Feem ntau, cov ntaub ntawv qhia kev sib xyaw ntawm cov cwj pwm no ntau dua li ib tus cwj pwm tshwj xeeb. Rau feem ntau qhov sib cuam tshuam ntawm cov ntaub ntawv, qhov sib faib ntawm lub teeb uas tau cuam tshuam nce nrog lub kaum sab xis ntawm qhov xwm txheej. Txoj cai ntawm kev xav muab lub kaum sab xis ntawm kev xav ntawm lub teeb. Nws hais tias lub kaum sab xis ntawm qhov teeb meem zoo ib yam li lub kaum sab xis ntawm lub teeb pom kev.
Qhov txawv ntawm Braggs Reflection thiab Ordinary Reflection yog dab tsi?
Reflection yog hais txog qhov kev hloov pauv ntawm lub wavefront ntawm qhov sib cuam tshuam ntawm ob qhov kev tshaj tawm sib txawv kom lub wavefront rov qab mus rau qhov nruab nrab los ntawm qhov nws pib. Braggs kev xav thiab kev xav zoo tib yam yog ob hom kev xav. Qhov sib txawv tseem ceeb ntawm Braggs kev xav thiab kev xav zoo ib yam yog qhov kev xav ntawm Braggs muaj lub kaum sab xis ntawm qhov xwm txheej thiab tus tubtxib saum ntuj ntawm kev tawg, whereas, hauv kev xav zoo ib yam, qhov teeb meem hluav taws xob tau cuam tshuam ntawm tib lub kaum sab xis.
Hauv qab infographic qhia txog qhov sib txawv ntawm Braggs kev xav thiab kev xav zoo ib yam.
Summary – Braggs Reflection vs Ordinary Reflection
Braggs kev xav thiab kev xav zoo ib yam yog ob hom kev xav. Qhov sib txawv tseem ceeb ntawm Braggs kev xav thiab kev xav zoo ib yam yog qhov kev xav ntawm Braggs muaj lub kaum sab xis ntawm qhov xwm txheej thiab tus tim tswv ntawm kev tawg tab sis, hauv kev xav zoo tib yam, qhov teeb meem hluav taws xob tau cuam tshuam ntawm tib lub kaum sab xis.
