Sib Piv Cov Tshuaj Sunscreens Thiab Lub Cev Sunscreens

Cov nqus hluav taws xob ultraviolet feem ntau yog cov organic sib txuas nrog cov qauv ntxhiab lossis cov qauv chromophore. Lub tshuab tseem ceeb ntawm kev nqis tes ua ntawm UV absorber yog siv lub kaw lus kaw siv hluav taws xob thiab tso siab rau transition-π * kev hloov pauv kom nqus photons, thaum ob π molecular orbitals nyob ze txaus, ob degenerate molecular orbitals yog tsim, ib qho nrog lub zog thiab ib qho nrog tsawg zog. Feem ntau, tus absorber yog yees-ruaj khov thiab lub zog tom qab nqus cov photons tuaj yeem tsim cov resonance quantum (feem ntau) los ntawm cov molecular resonance los yog tso tawm los ntawm fluorescence thiab phosphorescence, thiab thim rov qab isomerization ntawm lub molecule hloov lub absorber los ntawm lub xeev zoo siab rau lub xeev khov kho.

Cov qauv molecular ntawm DHHB muaj lub zog zoo meej thiab hydrogen ion hloov pauv cov nyhuv. Thaum DHHB lwg me me nqus lub teeb ci ultraviolet, lub zog tau nqus los ntawm kev hloov ntawm benzene nplhaib qauv thiab hydrogen ions uas nyob ib sab hauv molecule thiab tag nrho cov qauv molecular yuav raug hloov ib ntus. Tom qab lub lwg me me maj mam tawm lub zog tawm, cov qauv tsim qauv ntawm DHHB rov qab mus rau nws lub xeev qub.

Lub cev tshuaj pleev thaiv hnub lub teeb duab tawg duab

Titanium dioxide thiab zinc oxide yog ob qho khoom siv tiv thaiv lub cev tiv thaiv lub cev. Kev siv cov khoom ua rau lub cev tiv thaiv tshav ntuj nyob rau hauv sunscreens yog feem ntau los ntawm kev nqus rau attenuate UV rays thiab yog superimposed los ntawm qee qhov tawg. Raws li cov khoom siv me me kom sib xyaw (10-100 nm), cov khoom siv no yog cov khoom siv hluav taws xob muaj qhov sib txawv ntawm cov nplaim hluav taws xob ntawm qhov muaj siab thiab pawg sib xyaw. Cov qhab ntawm qhov sib txawv ntawm cov siv lead ua loj yog nyob rau hauv lub zog ntawm lub zog sib haum rau lub voos plaub ntawm 380 thiab 420 nm. Qhov me me ntawm qhov sib txuam me me, ntau dua qhov sib txawv ntawm lub zog, thiab qhov nqus ntawm ultraviolet lub teeb los ntawm kev tsa cov hluav taws xob los ntawm qhov muaj nqes mus rau kev sib dhos band.

Ob qho ntawm cov kev sib txuas no yog qhov tseem ceeb semiconductors. Noj cov titanium dioxide ua piv txwv, tom qab zoo siab los ntawm ultraviolet rays, nws yog N-hom semiconductor. Thaum ultraviolet lub teeb nrog lub yoj ntuag tsawg dua 400 nm yog tsis muaj kev cuam tshuam, cov xaim hluav taws xob ntawm qhov hluav taws xob interlayer nqus ultraviolet rays thiab zoo siab los tsim hluav taws xob-qhov, kom titanium dioxide muaj txoj haujlwm ua haujlwm ntawm nqus ultraviolet rays.

Tom qab ntawd, thaum lub hnub ci tshuaj tiv thaiv lub cev ntawm nano-titanium dioxide, thaum nws nqus tau cov tshuaj pleev thaiv hnub cov khoom muag, thaum twg los ua cov tshuaj pleev xim zoo? Qhov no muaj feem xyuam rau nws qhov me me. Cov kev sim tau pom tias ntev dua cov kab hluav taws xob dhau ntawm lub teeb ci ultraviolet, qhov thaiv ntawm nano-titanium dioxide nyob ntawm nws qhov nqus. Yog li, nws yog qhov tias nyob rau hauv UVB band, titanium dioxide yog tsuas yog nqus, thaum nyob rau hauv UVA band, nano titanium dioxide feem ntau tawg. Yog li no, txhawm rau kom ua tiav ntau txoj kev tiv thaiv UV, ob qho kev nqus thiab tawg yog qhov yuav tsum tau, yog li muaj qhov zoo tshaj plaws cov khoom tawg me me ntawm cov pa roj carbon dioxide, tsis kom tsawg li sai tau. Xav txog qhov teeb meem sib xyaw ntawm nano-titanium dioxide, feem ntau ntseeg tau hais tias qhov zoo me me ntawm qhov loj ntawm ultraviolet-tiv thaiv titanium dioxide yog 20-50 nm. Tau kawg, qhov loj me me tsuas yog qhov ntsuas ntawm lub hnub thaiv lub cev xav tau nyob rau hauv kev txhim kho tshuaj pleev thaiv hnub cov khoom lag luam thiab ntau cov ntsuas kev ntsuas yuav tsum raug txiav txim siab.