Modern Physics for Material Analysis PDF

Part 4 Modern physics for material analysis Quantitative data -> e.g. numerical data Qualitative data -> e.g. picture and colors Outline Scanning electron microscope (SEM) Transmission Electron Microscope (TEM) X-ray fluorescence (XRF) Optical microscope...

Part 4 Modern physics for material analysis Quantitative data -> e.g. numerical data Qualitative data -> e.g. picture and colors Outline Scanning electron microscope (SEM) Transmission Electron Microscope (TEM) X-ray fluorescence (XRF) Optical microscope Grain Size Defect https://www.doitpoms.ac.uk/tlplib/dislocations/observing.php Scanning electron microscope (SEM) Scanning electron microscope (SEM) SEM image of Human Hair SEM image of butterfly wing https://chem.libretexts.org/@go/page/21731 ภาพถ่าย protozoa จาก ภาพถ่าย protozoa กล้ อง กล้ องจุลทรรศน์อิเล็กตรอนแบบส่องกราด กล้ องจุลทรรศน์เชิงแสง จุลทรรศน์อิเล็กตรอนแบบส่อง (Scanning electron microscope, SEM) กราด Scanning electron microscope SEM images of local insects SEM images of various nanomaterials including (A) Gold nanoparticles https://www.jcu.edu.au/advanced-analytical- (B) Nanofibers (C) Carbon nanotubes (D) ZnO nanowire centre/resources/sem-images-of-local-insects-n.queensland International Food Research Journal 23(5): 1849-1856 (2016) Scanning electron microscope (SEM) Assume electron has de Broglie wavelength of 1 𝑥 10!"" 𝑚. Calculate the accelerating voltage that must be used. 1 𝑚𝑣 # = 𝑒𝑉$%% (1) 𝑉$%% = 1.38 𝑥 10( 𝑉 2 1 # 𝑚 𝑚𝑣 , = 𝑒𝑉$%% 𝑉$%% = 13.8 𝑘𝑉 2 𝑚 1 # 𝑝 = 𝑒𝑉$%% 2𝑚 1 ℎ # (focusing and control of ( ) = 𝑒𝑉$%% the electron beam) 2𝑚 𝜆 1 ℎ 𝑉$%% = ( )# 2,𝑚,𝑒 𝜆 1 6.34 𝑥 10!&( # 𝑉$%% = ,( ) 2 , (9.1𝑥 10!&" ) , (1.6𝑥 10!"' ) 1 𝑥 10!"" https://www.matsusada.com/column/sem_basic_knowledg e.html Scanning electron microscope (SEM) https://www.nanoscience.com/products/phenom-desktop-sem/ Scanning electron microscope (SEM): Electron-Matter interactions – Absorption Interaction mechanisms vary with radiation – Diffusion or diffraction nature and energy. – Refraction Reflection Refraction Source Absorption Diffusion Note: Diffusion àThe scattering or random reflection of a wave from a surface. 9 Scanning electron microscope (SEM): Electron-Matter interactions Interaction volume à The volumes involved in the production of secondary electron (SE), backscattered electron (BSE) and X-rays, form into a shape that ranges from a tear-drop to a semi circle within the specimen. à This shape is called an interaction volume and its depth and diameter depends on the kV as well as the density of the specimen. Approximately the top 15 nm of the volume comprises the zone from which SE can be collected, the top 40% is the region from which BSE can be collected and X rays can be collected from the entire region. http://materialsworld.utep.edu/Background/SCANNING%20ELECTR http://www.ammrf.org.au/myscope/sem/background/conc 10 ON%20MICROSCOPY/SccaningElectronMicroscopy.htm epts/interactions.php Scanning electron microscope (SEM): Electron-Matter interactions Interaction volume Incident electron beam 500-40,000 eV < 50 eV > 50 eV to incident beam (Brehmsstrahlung, accelerated e-1 emits radiation) 11 http://eaps4.iap.tuwien.ac.at/~werner/qes_tut_interact.html Scanning electron microscope (SEM): Electron-Matter interactions Electron-matter interactions can be divided into two classes: 1. Elastic scattering (Elastic Diffusion) 2. Inelastic scattering (Inelastic Diffusion) 1. Elastic scattering (Elastic Diffusion) à the electron trajectory within the specimen changes, but its kinetic energy and velocity remains essentially constant. No energy transfer à Low angle diffusion: Coulomb interaction with the electron cloud. à High angle diffusion, or back scattering: Coulomb interaction with nucleus. à Atom is not ionised. 12 Scanning electron microscope (SEM): Electron-Matter interactions 2. Inelastic scattering (Inelastic Diffusion) à An incident electron ejects a bound electron then changes direction, with an energy lowered by the electron bound energy. The incident electron can be slowed down by Coulomb interaction with the There is energy transfer, and the target nucleus. atom can be ionised. The ejected electron, of low energy, is called secondary electron SE. Inelastic interaction 13 Scanning electron microscope (SEM): Electron-Matter interactions à The sample is bombarded by an electron beam (primary electrons) in order to obtain a detailed topographical image of the surface of the sample from the secondary electrons. à Primary electrons can penetrate in the electron shells of the atoms composing the surface of the sample. à The energy (negative charge, mass, velocity) of these incident electrons can be converted to eject local electrons, so-called secondary electrons, from the shells of the atoms in the surface of the specimen. à This information can be utilized to reconstruct a detailed topographical image of the sample (SEI = Secondary Electrons Imaging). 14 Scanning electron microscope (SEM): Electron-Matter interactions Unclear surface structures High More edge effect High Resolution More charge-up More beam damage Accelerating Voltage 1 𝑚𝑣 ! = 𝑒𝑉"## 2 Clear surface structures Less edge effect Less charge-up Low Low Resolution Less beam damage 15 Scanning electron microscope (SEM): Electron-Matter interactions 30 kV, 2500x 5 kV, 2500x 16 http://www.medicine.mcgill.ca/femr/SEM%20Sample%20Prep%20JEOL.pdf Scanning electron microscope (SEM): Electron-Matter interactions Charge built up 4 kV 10 kV Beam Damage 4 kV 10 kV 17 http://www.medicine.mcgill.ca/femr/SEM%20Sample%20Prep%20JEOL.pdf Scanning electron microscope (SEM) Energy-Dispersive X-ray Spectroscopy (EDX) n=2→1 n=3→1 à It is possible to determine which elements are present in the surface layer of the sample (at a depth in the micrometer range) and where these elements are present ("mapping technique"). à Because each element emits an own characteristic energy value, the (Brehmsstrahlung) elements present in the micrometer range depth of the sample can be 18 determined. Scanning electron microscope(SEM) Energy-Dispersive X-ray Spectroscopy (EDX) 19 http://www.sciencedirect.com/science/article/pii/S0304389404001244 Scanning electron microscope (SEM) Energy-Dispersive X-ray Spectroscopy (EDX) Topographical view of the brass disc from secondary electron imaging (SEI), corresponding Mapping view for copper (Zinc mapping is not shown here) obtained by EDS detection, and overlay view of both signal in false color for a more accurate comparison. 20 Scanning electron microscope(SEM) Energy-Dispersive X-ray Spectroscopy (EDX) X-ray mapping is performed using Position- tagged Spectrometry (PTS). 21 http://www.macaulayanalytical.com/electronmicroscopy.php Transmission Electron Microscopy (TEM) Transmission Electron Microscopy (TEM) à In TEM, an image is acquired as a projection of the entire sample (including any internal information); however, due to electron absorption, typically only thin specimen sections are used to produce a two-dimensional image on the viewing screen. 23 https://bsp.med.harvard.edu/node/221 Transmission Electron Microscopy (TEM) Electron Backscattered electrons beam (In SEM instrument) Information on surface structure Secondary electrons (In SEM instrument) Information on surface structure Sample Transmitted electrons (In TEM instrument) Information on internal structure by dark and bright field image. 24 https://bsp.med.harvard.edu/node/221 Transmission Electron Microscopy (TEM) http://www.latech.com.sg/product/1425778447- TEM+Grids+with+Continuous+Film+(Pure+Carbon).html http://www.vcbio.science.ru.nl/en/fesem/tem/ http://emresolutions.com/product-info/tem-grids-gilder-grids/tem-grid-boxes Transmission Electron Microscopy (TEM) ‘The brightness of any specific area seen in the image is proportional to the quantity of electrons that penetrate through the specimen.’ 26 Transmission Electron Microscopy (TEM) High-resolution transmission electron microscopy (HRTEM) Normal TEM d spacing 27 Transmission Electron Microscopy (TEM) SEM TEM Nanomaterials 2018, 8(3), 133 Transmission Electron Microscopy (TEM) Nanoscale Res Lett 11, 186 (2016). X-ray fluorescence ~0.1 − 10 𝑛𝑚 Enclopaedia Britanica, Inc. X-ray interaction with matter Absorbed or trasmitted through the sample Knock out electron in atom and generate XRF Diffraced or scattered from a crystal structure 30 https://medlineplus.gov/xrays.html X-ray fluorescence Primary electron (SEM) (EDX) 31 X-ray fluorescence Note: Some elements do not give XRF signal. Their XRF energy are too low to transmit throught air and the Si-based detectors cannot detect them. In our EDXRF, the minimum is Na. 32 (thermofisher.com/xrf) X-ray fluorescence Mechanisms : (2) a) A primary x-ray generated by an X-ray tube is used to excite the sample. b) The sample, being irradiated by a primary x-ray source, leads to the (1) (3) emission of a fluorescent (or secondary) x-ray. (3) c) The detector detects the elemental composition of the materials. Then, analyzed by a signal processing unit. ~0.1 − 10 𝑛𝑚 (3) Enclopaedia Britanica, Inc. Detector X-ray tube Rhodium, Tungsten, !! of element Molybdenum Target, etc.) Count Fluorescent (secondary) x-ray primary x-ray !" of element sample Energy (KeV) SIMPLE schematic 33 X-ray fluorescence X-ray tube 1. Electrons are emitted from a cathode and Rhodium, Tungsten, accelerated by a voltage induced at the anode. Molybdenum Target, etc.) 2. They undergo deceleration or braking due to interactions with the atomic nuclei. This primary x-ray deceleration process results in the emission of Bremsstrahlung x-rays. sample 3. Bremsstrahlung x-rays can contribute to the background signal in the XRF spectrum. (they can (Roque, Rita. (2018). MsC thesis. be filtered or reduced to improve the signal-to- 10.13140/RG.2.2.16794.49600.) background ratio.) Blackground Bremsstrahlung x−rays Characteristic X−rays 𝑟𝑒𝑙𝑎𝑡𝑖𝑣𝑒 𝑖𝑛𝑡𝑒𝑛𝑠𝑖𝑡𝑦 of metal target Accelerated 𝑒 ! decelerated 𝑒 ! ! Bremsstrahlung x−rays " Characteristic X−rays # 𝑥 − 𝑟𝑎𝑦 𝑒𝑛𝑒𝑟𝑔𝑦 (𝐾𝑒𝑉) of metal target decelerated 𝑒 ! 34 photo 𝑒 ! X-ray fluorescence X-ray tube Rhodium, Tungsten, Detector Molybdenum Target, etc.) primary x-ray Fluorescent (secondary) x-ray sample Blackground (Yoneyama et. al., Scientific Reportsม 9, : 18831 (2019)) Rayleigh scattering (elastic scattering, ) Compton scattering (inelastic scattering) 1. Primary x-rays make elastic interact with electrons in 1. Primary x-ray strikes an electron of the sample. the sample. 2. The incident x-rays are scattered with an unchanged 2. Some energy is transferred to the electron in the collision, the x-ray energy. Rayleigh scattering occurs mostly at low energies leaves the collision with less energy. and for high atomic weight. 3. This can introduce background noise 3. The energy of the Compton-scattered X-ray is inversely proportional to the change in wavelength (Δλ). The larger the 35 scattering angle (θ), the greater the energy loss. X-ray fluorescence Blackground Bremsstrahlung (x-ray tube) https://chem.libretexts.org/Bookshelves/Analytical_Chemistry/Supplemental_Modules_%28Anal ytical_Chemistry%29/Analytical_Sciences_Digital_Library/Courseware/Introduction_to_XRF- (Roque, Rita. (2018). MsC thesis. 36 _An_Analytical_Perspective/2._Interpretation_of_XRF_Spectra 10.13140/RG.2.2.16794.49600.) X-ray fluorescence (O'Hea, Inna. (2015). MSc Thesis " The development of Phase-contrast imaging techniques towards implementation in clinical mammography".) (https://en.wikipedia.org/wiki/Characteristic_X- 37 ray#/media/File:CharacteristicRadiation.svg) X-ray fluorescence XRF Spectrum of Pure Zinc, taken with an Innov-X a-2000 X-Ray Fluorescence spectrometer with a Si-PiN detector (Hardware settings: Source: Ta; Voltage: 40 kV; Current: 24 uA; Filter: 250 uM Cu, Analytical Mode-FP algorithm, acquisition time 34s). 38 (http://www.xrfresearch.com/xrf-spectrum-zinc/) X-ray fluorescence Fig. A comparison of XRF spectra obtained by conventional XRF (Uo et al. (2015), Japanese Dental Science Review, 51 (1), 2-9.) 39 X-ray fluorescence Example 4: Pharmaceuticals 40 (H. Rebiere et al. Talanta 195 (2019) 490–496) X-ray fluorescence Example 5: Forensics A) Optical image of single glass particle. (B) Spectra of float glass chip illustrating the presence of a thin tin layer on one surface. (C) Spectra showing elemental differences of two Gun shot residue analysis from a coloured textile. glass types. 41 (Spectroscopy Europe/World Vol. 21, Issue 3 (2009))