Mikroskop transmisi résolusi kanthi dhuwur (HRTEM utawa HREM) yaiku kontras phase (kontras gambar mikroskop elektronika kanthi resolusi dhuwur dibentuk dening prabédan fase antara gelombang sing digambarake gelombang lan gelombang sing beda, Iki diarani kontras phase.) Mikroskop, sing menehi susunan atom saka pirang-pirang bahan kristal.
High-resolution transmission electron microscopy began in the 1950s. In 1956, JWMenter directly observed parallel strips of 12 Å copper phthalocyanine with a resolution of 8 Å transmission electron microscope, and opened high-resolution electron microscopy. The door to surgery. In the early 1970s, in 1971, Iijima Chengman used a TEM with a resolution of 3.5 Å to capture the phase contrast image of Ti2Nb10O29, and directly observed the projection of the atomic group along the incident electron beam. At the same time, the research on high resolution image imaging theory and analysis technology has also made important progress. In the 1970s and 1980s, the electron microscope technology was continuously improved, and the resolution was greatly improved. Generally, the large TEM has been able to guarantee a crystal resolution of 1.44 Å and a dot resolution of 2 to 3 Å. HRTEM can not only observe the lattice fringe image reflecting the interplanar spacing, but also observe the structural image of the arrangement of atoms or groups in the reaction crystal structure. Recently, Professor David A. Muller’s team at Cornell University in the United States used laminated imaging technology and an independently developed electron microscope pixel array detector to achieve a spatial resolution of 0.39 Å under low electron beam energy imaging conditions.
Saiki, mikroskop transmisi umume bisa nglakokaké HRTEM. Mikroskop transmisi kasebut dikelaskan dadi rong jinis: resolusi dhuwur lan analitis. TEM Résolusi dhuwur dilengkapi potongan kutub objektif kanthi resolusi dhuwur lan kombinasi diafragma, sing ndadekake kohefisi aberrasi sfera objektif sing luwih cilik; dene TEM analitis mbutuhake jumlah sing luwih gedhe kanggo macem-macem analisa. Sudut miring saka tahap sampel, saengga sepatu tlaga lensa objektif digunakake beda tinimbang jinis resolusi sing dhuwur, saengga bisa mengaruhi resolusi. Umumé, TEM résolusi dhuwur 200 biji résolusi 1.9 Å, dene 200 TV analitik kev nduwe 2,3 Å. Nanging iki ora mengaruhi gambar TEM sing njupuk gambar resolusi sing dhuwur.

As shown in Fig. 1, the optical path diagram of the high-resolution electron microscopy imaging process, when an electron beam with a certain wavelength (λ) is incident on a crystal with a crystal plane spacing d, the Bragg condition (2dsin θ = λ) is satisfied, A diffracted wave is generated at an angle (2θ). This diffracted wave converges on the back focal plane of the objective lens to form a diffraction spot (in an electron microscope, a regular diffraction spot formed on the back focal plane is projected onto the phosphor screen, which is a so-called electron diffraction pattern). When the diffracted wave on the back focal plane continues to move forward, the diffracted wave is synthesized, an enlarged image (electron microscopic image) is formed on the image plane, and two or more large objective lens stops can be inserted on the back focal plane. Wave interference imaging, called high-resolution electron microscopy, is called a high-resolution electron microscopic image (high-resolution microscopic image).
Kaya sing kasebut ing ndhuwur, gambar mikroskopik kanthi resolusi dhuwur yaiku gambar mikroskopis kontras kanthi phase sing dibentuk kanthi ngliwati rasuk fokus ing lensa fokus ing lensa objektif lan sawetara balok sing beda liwat murid objektif, amarga koherensi fase. Amarga beda jumlah balok sing beda-beda sing melu imaging, gambar resolusi dhuwur kanggo macem-macem jeneng dipikolehi. Amarga kahanan bedhane lan kekandelan sampel sing beda, mikrofon elektron resolusi dhuwur kanthi informasi struktural beda bisa dipérang dadi lima kategori: pinggir kisi, gambar strukture siji-dimensi, gambar kisi rong dimensi (gambar siji-sel), rong dimensi gambar struktur (gambar skala atom: gambar struktur kristal), gambar khusus.
Kancing kisi: Yen rasuk transmisi ing pesawat fokus mburi dipilih dening lensa objektif, lan balok bedhil beda-beda, siji pola dimensi siji-dimensi kanthi owah-owahan berkala intensitas dipikolehi (ditampilake dening segitiga ireng ing 2 (f)) Iki bedane antara pinggiran kisi lan gambar kisi lan gambar struktural, sing ora mbutuhake balok elektron persis padha karo pesawat kisi. Bener, ing pengamatan crystallites, mendhak, lan liya-liyane, pinggir kisi asring dijupuk kanthi gangguan ing antarane gelombang ramalan lan gelombang bedhane. Yen pola difraksi elektron saka bahan kayata kristal, foto ibadah bakal ditampilake kaya sing ditampilake (a) Gambar 2.

Gambar struktur siji-dimensi: Yen conto duwe miring tartamtu, supaya balok elektron kedadeyan sing padha karo pola kristal tinamtu, bisa nyukupi pola panyebaran dimensi siji-dimensi sing dituduhake ing Gambar 2 (b) ( distribusi simetris babagan titik pangiriman) pola Penyebaran). Ing pola bedakan iki, gambar résolusi sing dhuwur sing ditrapake miturut kondhisi fokus optimal beda karo pinggir kisi, lan gambar struktur siji-dimensi ngemot informasi struktur kristal, yaiku, gambar struktur siji-dimensi, kaya sing dituduhake ing Gambar 3 (gambar struktural siji-dimensi resolusi dhuwur saka Biografi superconduktor adhedhasar Biografi sing dituduhake.
Two-dimensional lattice image: If the electron beam is incident parallel to a certain crystal axis, a two-dimensional diffraction pattern can be obtained (two-dimensional symmetric distribution with respect to the central transmission spot, shown in Fig. 2(c)). For such an electron diffraction pattern. In the vicinity of the transmission spot, a diffraction wave reflecting the crystal unit cell appears. In the two-dimensional image generated by the interference between the diffracted wave and the transmitted wave, a two-dimensional lattice image showing the unit cell can be observed, and this image contains information on the unit cell scale. However, information that does not contain an atomic scale (into atomic arrangement), that is, a two-dimensional lattice image is a two-dimensional lattice image of single crystal silicon as shown in Fig. 3(d).
Two-dimensional structure image: a diffraction pattern as shown in Fig. 2(d) is obtained. When a high-resolution electron microscope image is observed with such a diffraction pattern, the more diffraction waves involved in imaging, the information contained in the high-resolution image is also The more. A high-resolution two-dimensional structure image of the Tl2Ba2CuO6 superconducting oxide is shown in Fig. 3(e). However, the diffraction of the high-wavelength side with higher resolution limit of the electron microscope is unlikely to participate in the imaging of the correct structure information, and becomes the background. Therefore, within the range allowed by the resolution. By imaging with as many diffracted waves as possible, it is possible to obtain an image containing the correct information of the arrangement of atoms within the unit cell. The structure image can only be observed in a thin region excited by the proportional relationship between the wave participating in imaging and the thickness of the sample.

Gambar khusus: Ing pola bedakan pesawat fokus mburi, sisipan aperture mung milih imaging gelombang khusus supaya bisa mirsani gambar kontras informasi struktural spesifik. Conto sing khas yaiku struktur sing dhawuh kaya. Pola panyebaran elektron sing cocog dituduhake ing Gambar 2 (e) minangka pola panyebaran elektron saka Au, Cd menehi aloi. Struktur sing diprentahake adhedhasar struktur kubik sing dipusatake kanthi larutan atom Cd kanthi teratur. Gambar 2 (e) pola bedhah elektron saya ringkih kajaba refleksi pola kisi dhasar (020) lan (008). Renungan kisi sing mrentah, nggunakake lensa objektif kanggo nggambarake refleksi kisi dhasar, nggunakake gelombang transmisi lan imaging refleksi kisi, mung atom Cd sing duwe poin utawa titik peteng kayata resolusi dhuwur kaya sing dituduhake ing Gambar 4.

Minangka ditampilake ing Gambar 4, gambar résolusi sing dhuwur beda-beda gumantung karo kekandelan sampel sing cedhak karo resolusi dhuwur sing paling dhuwur. Dadi, nalika entuk gambar resolusi sing dhuwur, kita ora bisa ngerteni apa gambar resolusi dhuwur. Sampeyan kudu nindakake simulasi komputer dhisik kanggo ngetung struktur materi ing ngisor kekandelan sing beda. Gambar resolusi sing dhuwur kanggo zat kasebut. Serangkaian gambar resolusi dhuwur sing diwilang saka komputer dibandhingake karo gambar resolusi dhuwur sing dipikolehi dening eksperimen kasebut kanggo nemtokake gambar resolusi dhuwur sing dipikolehi dening eksperimen kasebut. Gambar simulasi komputer sing dituduhake ing Gambar 5 dibandhingake gambar resolusi dhuwur sing dipikolehi dening eksperimen kasebut.

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