{"id":5402,"date":"2022-04-12T11:06:34","date_gmt":"2022-04-12T09:06:34","guid":{"rendered":"https:\/\/www.enviblog.cz\/blog\/?p=5402"},"modified":"2022-04-12T11:06:34","modified_gmt":"2022-04-12T09:06:34","slug":"elektronovy-mikroskop-ve-sluzbach-chmu-ii-dil","status":"publish","type":"post","link":"https:\/\/www.enviblog.cz\/blog\/2022\/04\/12\/elektronovy-mikroskop-ve-sluzbach-chmu-ii-dil\/","title":{"rendered":"Elektronov\u00fd mikroskop ve slu\u017eb\u00e1ch \u010cHM\u00da \u2013 II. d\u00edl"},"content":{"rendered":"

V\u00a0prvn\u00edm d\u00edlu<\/a> \u010dl\u00e1nku jste se dozv\u011bd\u011bli n\u011bco o historii elektronov\u00e9 mikroskopie. Tento d\u00edl bude zam\u011b\u0159en na to, jak konkr\u00e9tn\u011bji funguje skenovac\u00ed (nebo tak\u00e9 rastrovac\u00ed, \u0159\u00e1dkovac\u00ed) elektronov\u00fd mikroskop, a v\u00a0\u010dem n\u00e1m v\u00a0\u010cHM\u00da m\u016f\u017ee b\u00fdt n\u00e1pomocen.\u00a0<\/strong><\/em><\/p>\n

Na elektronovou mikroskopii se d\u00e1 nahl\u00ed\u017eet sv\u00fdm zp\u016fsobem jako na jednu z praktick\u00fdch aplikac\u00ed kvantov\u00e9 fyziky. Mus\u00edm \u0159\u00edct, \u017ee kvantov\u00e1 fyzika m\u011b v\u017edy fascinovala, proto\u017ee se v\u00a0n\u00ed sv\u011bt projevuje dost odli\u0161n\u011b, ne\u017e na co jsme zvykl\u00ed v\u00a0r\u00e1mci klasick\u00e9 fyziky. Nebudu tu zbyte\u010dn\u011b zach\u00e1zet do detail\u016f, to by t\u011bch d\u00edl\u016f o elektronov\u00e9 mikroskopii muselo b\u00fdt n\u011bkolik, a c\u00edlem ur\u010dit\u011b nen\u00ed zahltit \u010dten\u00e1\u0159e teori\u00ed. Co je ale dobr\u00e9 v\u011bd\u011bt, je to, \u017ee mezi st\u011b\u017eejn\u00ed pil\u00ed\u0159e kvantov\u00e9 fyziky pat\u0159\u00ed tzv. dualita \u010d\u00e1stice a vln\u011bn\u00ed, \u010dili \u017ee \u010d\u00e1stice lze popsat (chovaj\u00ed se) sou\u010dasn\u011b i jako vlny. Tuto hypot\u00e9zu vyslovil roku 1924 Louis de Broglie, kter\u00fd ka\u017ed\u00e9mu pohybuj\u00edc\u00edmu se t\u011blesu p\u0159i\u0159adil i ur\u010ditou vlnovou d\u00e9lku de Broglieho vlny. K dal\u0161\u00edm z\u00e1kladn\u00edm princip\u016fm pat\u0159\u00ed to, \u017ee u \u010d\u00e1stic nelze sou\u010dasn\u011b zm\u011b\u0159it jejich polohu a hybnost \u010di \u017ee pozorov\u00e1n\u00ed m\u00e1 v\u017edy vliv na pozorovan\u00fd syst\u00e9m. Z\u00e1rove\u0148 \u00a0se zde pracuje s tzv. kvantov\u00e1n\u00edm energie-z\u00e1\u0159en\u00ed je vyza\u0159ov\u00e1no po\u00a0d\u00e1vk\u00e1ch<\/a>\u00a0(bal\u00ed\u010dc\u00edch) energie, kde kvantum elektromagnetick\u00e9ho z\u00e1\u0159en\u00ed p\u0159edstavuje nejmen\u0161\u00ed \u201ekousek\u201c z\u00e1\u0159en\u00ed (La Bellac, M., 2011).<\/p>\n

Elektronov\u00e1 mikroskopie je metoda zalo\u017een\u00e1 pr\u00e1v\u011b na vlnov\u00fdch vlastnostech elektron\u016f. Z vlnov\u00e9 povahy svazku elektron\u016f vypl\u00fdv\u00e1 schopnost elektronov\u00fdch mikroskop\u016f rozli\u0161it detaily \u0159\u00e1dov\u011b v\u00a0jednotk\u00e1ch a\u017e desetin\u00e1ch nanometr\u016f. Podle fyzik\u00e1ln\u00ed tvorby obrazu d\u011bl\u00edme elektronovou mikroskopii na transmisn\u00ed elektronovou mikroskopii (TEM) a skenovac\u00ed elektronovou mikroskopii (SEM), kterou vyu\u017e\u00edv\u00e1me na\u00a0brn\u011bnsk\u00e9 pobo\u010dce \u010cHM\u00da a na kterou\u00a0 se\u00a0 tedy zam\u011b\u0159\u00edme. Popi\u0161me si jej\u00ed z\u00e1kladn\u00ed princip: mikrostruktura vzorku je studov\u00e1na ve vakuu (aby se mimo jin\u00e9 zabr\u00e1nilo interakci elektron\u016f s\u00a0jin\u00fdmi \u010d\u00e1sticemi vzduchu) pomoc\u00ed elektronov\u00e9ho svazku, kter\u00fd vznik\u00e1 emis\u00ed elektron\u016f z\u00a0tzv. elektronov\u00e9 trysky neboli zdroje. Elektrony mohou b\u00fdt emitov\u00e1ny z\u00a0termoemisn\u00edho zdroje (nap\u0159. \u017ehaven\u00e9 wolframov\u00e9 vl\u00e1kno) \u010di z\u00a0autoemisn\u00edho-studen\u00e9ho zdroje (FEG, Schottkyho autoemisn\u00ed tryska-na rozd\u00edl od termoemisn\u00edho zdroje m\u00e1 vy\u0161\u0161\u00ed \u017eivotnost). Elektrony ze zdroje jsou d\u00e1le urychlov\u00e1ny nap\u011bt\u00edm a\u017e 30 kV ke kladn\u011b nabit\u00e9\u00a0anod\u011b. Pot\u00e9 elektrony vstupuj\u00ed do elektronov\u00e9 optiky. Elektronov\u00e1 optika mus\u00ed b\u00fdt konstruov\u00e1na tak, aby byl p\u0159en\u00e1\u0161en\u00fd elektrick\u00fd proud maxim\u00e1ln\u00ed, aby v\u0161echny elektrony svazku\u00a0 m\u011bly\u00a0 stejnou energii a sou\u010dasn\u011b aby elektrony byly fokusov\u00e1ny na minim\u00e1ln\u00ed plochu vzorku. Vyu\u017e\u00edvaj\u00ed se elektrostatick\u00e9 a elektromagnetick\u00e9 \u010do\u010dky, \u010dili na elektrony p\u016fsob\u00ed elektrostatick\u00e9, magnetick\u00e9 \u010di elektromagnetick\u00e9 pole.<\/p>\n

Na z\u00e1klad\u011b interakce prim\u00e1rn\u00edch elektron\u016f (emitovan\u00fdch ze zdroje) s atomy vzorku vznikaj\u00ed r\u016fzn\u00e9 typy sign\u00e1l\u016f, kter\u00e9 jsou d\u00e1le analyzov\u00e1ny \u0159\u00edd\u00edc\u00edm po\u010d\u00edta\u010dem a na z\u00e1klad\u011b kter\u00fdch je vykreslov\u00e1n obraz analyzovan\u00e9ho vzorku na po\u010d\u00edta\u010di. P\u0159i dopadu elektron\u016f na vzorek doch\u00e1z\u00ed: 1. k emisi sekund\u00e1rn\u00edch elektron\u016f (jsou to elektrony \u201evyra\u017een\u00e9\u201c z vn\u011bj\u0161\u00edch elektronov\u00fdch slupek atom\u016f vzorku, poskytuj\u00ed informaci p\u0159ev\u00e1\u017en\u011b o topografii, sn\u00edm\u00e1 je tzv. SE detektor, p\u0159i\u010dem\u017e sign\u00e1l poch\u00e1z\u00ed z hloubek jen n\u011bkolika nm), 2. \u010d\u00e1st elektron\u016f je absorbov\u00e1na vzorkem (ty se zde analyticky nevyu\u017e\u00edvaj\u00ed), 3. \u010d\u00e1st elektron\u016f se odraz\u00ed (tzv. pru\u017en\u00e9 elektronov\u00e9 sr\u00e1\u017eky, tyto elektrony nesou informaci o materi\u00e1lov\u00e9m kontrastu (f\u00e1zov\u00e9m slo\u017een\u00ed) a sn\u00edm\u00e1 je tzv. BSE detektor, p\u0159i\u010dem\u017e po\u010det zp\u011btn\u011b odra\u017een\u00fdch elektron\u016f je z\u00e1visl\u00fd na protonov\u00e9m \u010d\u00edsle prvku-\u010d\u00edm je vy\u0161\u0161\u00ed, t\u00edm v\u00edce elektron\u016f odr\u00e1\u017e\u00ed a na obrazovce se to projev\u00ed jako sv\u011btlej\u0161\u00ed m\u00edsta) a\u00a0 4. doch\u00e1z\u00ed i k emisi Augerov\u00fdch elektron\u016f, foton\u016f \u010di emisi rentgenov\u00e9ho z\u00e1\u0159en\u00ed. My vyu\u017e\u00edv\u00e1me na na\u0161em pracovi\u0161ti detekci rentgenov\u00e9ho z\u00e1\u0159en\u00ed, a to pomoc\u00ed EDS detektoru. P\u0159i dopadu elektron\u016f na vzorek m\u016f\u017ee doj\u00edt k uvoln\u011bn\u00ed elektronu z dan\u00e9 energetick\u00e9 hladiny a t\u00edm k p\u0159echodu n\u011bkter\u00e9ho z elektron\u016f z vy\u0161\u0161\u00ed energetick\u00e9 hladiny do t\u00e9to vakance (ni\u017e\u0161\u00ed hladiny)-uvoln\u00ed se z\u00e1rove\u0148 kvantum energie a dojde k emisi charakteristick\u00e9ho rentgenov\u00e9ho z\u00e1\u0159en\u00ed, kter\u00e9 se pou\u017e\u00edv\u00e1 pro anal\u00fdzu chemick\u00e9ho slo\u017een\u00ed vzork\u016f (N\u011bme\u010dek J., 2018).<\/p>\n

\"\"<\/a><\/p>\n

Zjednodu\u0161en\u00e9 sch\u00e9ma SEM (zdroj<\/a>)<\/em><\/p>\n

Mezi v\u00fdhody SEM pat\u0159\u00ed ve srovn\u00e1n\u00ed s\u00a0TEM mnohem men\u0161\u00ed po\u017eadavky na vzorek, respektive jeho tlou\u0161\u0165ku (U TEM mus\u00ed m\u00edt jen n\u011bkolik des\u00edtek nm). Nevodiv\u00fd vzorek ov\u0161em mus\u00ed b\u00fdt pokoven, aby se \u201enenab\u00edjel\u201c-my zde pou\u017e\u00edv\u00e1me metodu iontov\u00e9ho napra\u0161ov\u00e1n\u00ed (zalo\u017eena na usm\u011brn\u011bn\u00e9m v\u00fdboji v argonov\u00e9 atmosf\u00e9\u0159e \u00fa\u010dinkem elektrick\u00e9ho nap\u011bt\u00ed). Za nev\u00fdhody SEM lze pova\u017eovat nap\u0159. velk\u00e9 n\u00e1roky na prostor a vysokou po\u0159izovac\u00ed cenu.<\/p>\n

\"\"<\/a><\/p>\n

Metoda iontov\u00e9ho napra\u0161ov\u00e1n\u00ed \u201ev akci\u201c, napra\u0161ova\u010dka Quorum Q150R.<\/em><\/p>\n

\"\"<\/a><\/p>\n

Skenovac\u00ed elektronov\u00fd mikroskop MIRA3 firmy Tescan s.r.o. v laborato\u0159i \u00faseku kvality ovzdu\u0161\u00ed \u010cHM\u00da Brno.<\/em><\/p>\n

My se na \u00faseku kvality ovzdu\u0161\u00ed sna\u017e\u00edme na SEM pohl\u00ed\u017eet jako na pomocnou metodu p\u0159i ur\u010dov\u00e1n\u00ed zdroj\u016f zne\u010di\u0161t\u011bn\u00ed ovzdu\u0161\u00ed. Studujeme morfologii a chemick\u00e9 slo\u017een\u00ed prachov\u00fdch \u010d\u00e1stic zachycen\u00fdch na filtrech. Pr\u00e1v\u011b znalost morfologie \u010d\u00e1stic je mnohdy velmi u\u017eite\u010dnou pom\u016fckou-jinak vypadaj\u00ed \u010d\u00e1stice poch\u00e1zej\u00edc\u00ed nap\u0159. ze spalovac\u00edch proces\u016f, odli\u0161n\u011b pak ty, jejich\u017e zdrojem je nap\u0159\u00edklad p\u016fda.<\/p>\n

\"\"<\/a><\/p>\n

Exponovan\u00fd polykarbon\u00e1tov\u00fd filtr, k vid\u011bn\u00ed jsou prachov\u00e9 \u010d\u00e1stice r\u016fzn\u00fdch tvar\u016f a velikost\u00ed, a takt\u00e9\u017e samotn\u00e9 p\u00f3ry filtru.<\/em><\/p>\n

 <\/p>\n

Zdroje:<\/strong><\/p>\n

Le Bellac, M. (2011).\u00a0Quantum physics. Cambridge University Press.<\/p>\n

N\u011aME\u010cEK, J. (2018). Metody skenovac\u00ed elektronov\u00e9 mikroskopie SEM a analytick\u00e9 techniky.\u00a0Mikromechanika a popis mikrostruktury materi\u00e1l\u016f [online]. \u010cVUT Praha, Fakulta stavebn\u00ed.<\/p>\n","protected":false},"excerpt":{"rendered":"

V\u00a0prvn\u00edm d\u00edlu \u010dl\u00e1nku jste se dozv\u011bd\u011bli n\u011bco o historii elektronov\u00e9 mikroskopie. Tento d\u00edl bude zam\u011b\u0159en na to, jak konkr\u00e9tn\u011bji funguje skenovac\u00ed (nebo tak\u00e9 rastrovac\u00ed, \u0159\u00e1dkovac\u00ed) elektronov\u00fd mikroskop, a v\u00a0\u010dem n\u00e1m v\u00a0\u010cHM\u00da m\u016f\u017ee b\u00fdt n\u00e1pomocen.\u00a0 Na elektronovou mikroskopii se d\u00e1 nahl\u00ed\u017eet sv\u00fdm zp\u016fsobem jako na jednu z praktick\u00fdch aplikac\u00ed kvantov\u00e9 fyziky. Mus\u00edm \u0159\u00edct, \u017ee kvantov\u00e1 fyzika […]<\/p>\n","protected":false},"author":20,"featured_media":5406,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","enabled":false},"version":2}},"categories":[5],"tags":[46],"coauthors":[271],"class_list":["post-5402","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-ovzdusi","tag-sem","entry","has-media"],"jetpack_publicize_connections":[],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"https:\/\/www.enviblog.cz\/blog\/wp-content\/uploads\/2022\/04\/133.jpg","jetpack_shortlink":"https:\/\/wp.me\/pa1A1I-1p8","_links":{"self":[{"href":"https:\/\/www.enviblog.cz\/blog\/wp-json\/wp\/v2\/posts\/5402","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.enviblog.cz\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.enviblog.cz\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.enviblog.cz\/blog\/wp-json\/wp\/v2\/users\/20"}],"replies":[{"embeddable":true,"href":"https:\/\/www.enviblog.cz\/blog\/wp-json\/wp\/v2\/comments?post=5402"}],"version-history":[{"count":1,"href":"https:\/\/www.enviblog.cz\/blog\/wp-json\/wp\/v2\/posts\/5402\/revisions"}],"predecessor-version":[{"id":5407,"href":"https:\/\/www.enviblog.cz\/blog\/wp-json\/wp\/v2\/posts\/5402\/revisions\/5407"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.enviblog.cz\/blog\/wp-json\/wp\/v2\/media\/5406"}],"wp:attachment":[{"href":"https:\/\/www.enviblog.cz\/blog\/wp-json\/wp\/v2\/media?parent=5402"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.enviblog.cz\/blog\/wp-json\/wp\/v2\/categories?post=5402"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.enviblog.cz\/blog\/wp-json\/wp\/v2\/tags?post=5402"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/www.enviblog.cz\/blog\/wp-json\/wp\/v2\/coauthors?post=5402"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}