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Characterization of nanoparticles

Introduction
Nanoparticle characterization techniques
Electron Microscope
Scanning electron microscope
Transmission electron Microscope
X-ray powder diffraction
Nuclear Magnetic Resonance

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Characterization of nanoparticles

  1. 1. 1 Characterization of Nanoparticles Dr. Anil Pethe Shobhaben Pratapbhai Patel School of Pharmacy & Technology Management, SVKM’S NMIMS, Mumbai
  2. 2.  Introduction  Nanoparticle characterization techniques  Electron Microscope  Scanning electron microscope  Transmission electron Microscope  X-ray powder diffraction  Nuclear Magnetic Resonance Contents
  3. 3.  Characterization refers to the study of material’s features such as its composition, structure,& various properties like physical, electrical, magnetic etc. Nano = 10-9 (extremely small) Particle = Small piece of matter  Nanoparticle is a microscopic particle whose size is measured in nanometers (nm).  These particles can be spherical, tubular, or irregularly shaped and can exist in fused, aggregated or agglomerated forms.
  4. 4. Scale of Nano particles
  5. 5. Optical (Imaging) Probe Characterization Techniques Electron Probe Characterization Techniques Scanning Probe Characterization Techniques Photon(Spectroscopic) Probe Characterization Techniques Ion-particle probe Characterization Techniques Thermodynamic Characterization Techniques Nano particles Characterization Techniques
  6. 6. Optical(Imaging) Probe Characterization Techniques Optical (Imaging) Probe Characterization Techniques Acronym Technique Utility CLSM Confocal laser-scanning microscopy Imaging/ultrafine morphology SNOM Scanning near-field optical microscopy Rastered images 2PFM Two-photon fluorescence microscopy Fluorophores/biological systems DLS Dynamic light scattering Particle sizing BAM Brewster angle microscopy Gas-liquid interface Imaging
  7. 7. Electron Probe Characterization Techniques Acronym Technique Utility SEM Scanning Electron Microscopy Imaging/ topology morphology EPMA Electron Probe Microanalysis Particle size/ local chemical analysis TEM Transmission Electron Microscopy Imaging/ Particle size shape HRTEM High Resolution Transmission Electron Microscopy Imaging structure chemical analysis LEED Low Energy Electron Diffraction Surface/ adsorbate bonding EELS Electron Energy Loss Spectroscopy Inelastic electron interaction AES Auger Electron Spectroscopy Chemical surface analysis
  8. 8. Scanning Probe Characterization Techniques Acronym Technique Utility AFM Atomic Force Microscopy Imaging/ topology/ surface structure CFM Chemical Force Microscopy Chemical/surface analysis MFM Magnetic Force Microscopy Magnetic material analysis STM Scanning Tunnelling Microscopy Topology/Imaging /surface APM Atomic Probe Microscopy Three dimensional Imaging FIM Field Ion Microscopy Chemical profiles/ atomic spacing APT Atomic probe tomography Position sensitive lateral location of atoms
  9. 9. Photon(Spectroscopic) Probe Characterization Techniques Acronym Technique Utility UPS Ultraviolet photoemission spectroscopy Surface analysis UVVS UV Visible spectroscopy Chemical analysis AAS Atomic absorption spectroscopy Chemical analysis ICP Inductively coupled plasma spectroscopy Elemental analysis FS Fluorescence spectroscopy Elemental analysis LSPR Localized surface plasmon resonance Nanosized particle analysis
  10. 10. Ion-particle probe Characterization Techniques Acronym Technique Utility RBS Rutherford back scattering Quantitative- Qualitative elemental analysis SANS Small angle neutron scattering Surface characterization NRA Nuclear reaction analysis Depth profiling of solid thin film RS Raman Spectroscopy Vibration analysis XRD X-ray diffraction Crystal structure EDX Energy dispersive X-ray spectroscopy Elemental analysis SAXS Small angle X-ray scattering Surface analysis/ particle sizing (1-100 nm) CLS Cathodoluminescence Characteristics emission NMR Nuclear magnetic resonance spectroscopy Analysis of odd no. of nuclear species
  11. 11. Thermodynamic Characterization Techniques Acronym Technique Utility TGA Thermal gravimetric analysis Mass loss Vs. Temperature DTA Differential thermal analysis Reaction heat capacity DSC Differential scanning calorimetry Reaction heat phase changes NC Nanocalorimetry Latent heats of fusion BET Brunauer-Emmett-Teller method Surface area analysis Sears Sears method Colloid size, specific surface area
  12. 12.  Light microscopes cannot resolve structures closer than 200 nm  Electron microscopes have greater resolving power and magnification  Magnifies objects 10,000X to 100,000X  Detailed views of bacteria, viruses, internal cellular structures, molecules, and large atoms  Two types • Transmission electron microscopes • Scanning electron microscopes The Electron Microscope
  13. 13. • Energy source is a beam of electrons • Image is created and viewed on a monitor • TEM (transmission electron microscope) utilizes staining procedures prior to use • SEM (scanning electron microscope) adds three-dimensional viewing The Electron Microscope
  14. 14. • Beams of electrons are used to produce images • Wavelength of electron beam is much shorter than light, resulting in much higher resolution The Electron Microscope
  15. 15. • In transmission electron microscopy electrons pass through thin specimens (50-1000 nm). BULK BEAM • In scanning electron microscopy signals emitted from the surface of thick specimens. NARROW BEAM Physical Limitations
  16. 16. • Uses electrons reflected from the surface of a specimen to create image • Produces a 3-dimensional image of specimen’s surface features Scanning Electron Microscope (SEM)
  17. 17. Scanning Electron Microscope (SEM)
  18. 18. Light Microscopy Vs. Electron Microscopy
  19. 19.  The SEM is an instrument that produces a largely magnified image by using electrons instead of light to form an image.  A beam of electrons is produced at the top of the microscope by an electron gun.  The electron beam follows a vertical path through the microscope, which is held within a vacuum.  The beam travels through electromagnetic fields and lenses, which focus the beam down toward the sample.  Once the beam hits the sample, electrons and X-rays are ejected from the sample.  Detectors collect these X-rays, backscattered electrons, and secondary electrons and convert them into a signal that is sent to a screen similar to a television screen. This produces the final image. Working of SEMWorking of Scanning Electron Microscope (SEM)
  20. 20. (Emiliania huxleyi, a haptophyte alga) http://starcentral.mbl.edu/ SEM IMAGE
  21. 21. SEM IMAGES
  22. 22. Transmission Electron Microscope (TEM)
  23. 23. • Electrons scatter when they pass through thin sections of a specimen • Transmitted electrons (those that do not scatter) are used to produce image • Denser regions in specimen, scatter more electrons and appear darker Transmission Electron Microscope (TEM)
  24. 24. Working of Transmission Electron Microscope (TEM)  Unlike SEM that bounces electrons off the surface of a sample to produce an image, Transmission Electron Microscopes (TEMs) shoot the electrons completely through the sample.  TEMs work by using a tungsten filament to produce an electron beam in a vacuum chamber.  The emitted electrons are accelerated through an electromagnetic field that also narrowly focuses the beam. The beam is then passed through the sample material. The specially prepared sample is a very thin (less than 100nm) slice of material. The electrons that pass through the sample hit a phosphor screen, CCD or film and produce an image. Where the sample has less density, more electrons get through and the image is brighter. A darker image is produced in areas where the sample is more dense and therefore less electrons pass through.  TEMs can produce images with resolution down to 0.2nm. This resolution is smaller than the size of most atoms and therefore images can be produced using TEM that show the true structural arrangement of atoms in the sample material.
  25. 25. • X-ray diffraction is used to obtain structural information about crystalline solids. • Useful in biochemistry to solve the 3D structures of complex biomolecules. • Bridge between physics, chemistry, and biology. • X-ray diffraction is important for  Solid-state physics  Biophysics  Medical physics  Chemistry and Biochemistry Introduction of X-ray Diffraction
  26. 26. • Most useful in the characterisation of • Crystalline materials; • Ceramics, • Metals, • Intermetallic, • Minerals, • Inorganic compounds • Rapid and non destructive techniques • Provide information on unit cell dimension Structural Analysis • X-ray diffraction provides most definitive structural information • Interatomic distances and bond angles What is X-ray Diffraction
  27. 27. • Beams of electromagnetic radiation • *smaller wavelength than visible light, • *higher energy • *more penetrative
  28. 28. • (1895) X-rays discovered by Roentgen • (1914) First diffraction pattern of a crystal made by Knipping and von Laue • (1915) Theory to determine crystal structure from diffraction pattern developed by Bragg. • (1953) DNA structure solved by Watson and Crick • Now Diffraction improved by computer technology; methods used to determine atomic structures and in medical applications History of X-ray Diffraction
  29. 29. • The prime component in X-Ray tube are filament (cathode), vacuum room, anode, and high voltage • When high energy electrons strike an anode in a sealed vacuum, x-rays are generated. Anodes are often made of copper, iron or molybdenum. • High energy electron come from heated filament in X-Ray tube. • X-rays are electromagnetic radiation. • They have enough energy to cause ionization. X-ray Production
  30. 30. • English physicists Sir W.H. Bragg and his son Sir W.L. Bragg developed a relationship in 1913 to explain why the cleavage faces of crystals appear to reflect X-ray beams at certain angles of incidence (theta, θ). • d is the distance between atomic layers in a crystal, • lambda λ is the wavelength of the incident X-ray beam; • n is an integer. • This observation is an example of X-ray wave interference (Roentgen strahl interferenzen), commonly known as X-ray diffraction (XRD), and was direct evidence for the periodic atomic structure of crystals postulated for several centuries. Bragg’s Law nλ = 2d sin θ
  31. 31. • Wave Interacting with a Single Particle • Incident beams scattered uniformly in all directions • Wave Interacting with a Solid • Scattered beams interfere constructively in some directions, producing diffracted beams • Random arrangements cause beams to randomly interfere and no distinctive pattern is produced • Crystalline Material • Regular pattern of crystalline atoms produces regular diffraction pattern. • Diffraction pattern gives information on crystal structure How Diffraction Works
  32. 32. • X-ray source • Device for restricting wavelength range “goniometer” • Sample holder • Radiation detector • Signal processor and readout Components of X-ray Diffraction
  33. 33. X-ray Diffraction Instrumentation  X-ray diffractometers consist of three basic elements:  an X-ray tube,  a sample holder,  an X-ray detector.  X rays are generated in a cathode ray tube by heating a filament to produce electrons, accelerating the electrons toward a target by applying a voltage, and bombarding the target material with electrons.  When electrons have sufficient energy to dislodge inner shell electrons of the target material, characteristic X-ray spectra are produced. These spectra consist of several components, the most common being Kα and Kβ.  Kαconsists, in part, of Kα1 and Kα2.  Kα1 has a slightly shorter wavelength and twice the intensity as Kα2.  The specific wavelengths are characteristic of the target material (Cu, Fe, Mo, Cr). Filtering, by foils or crystal monochrometers, is required to produce monochromatic X- rays needed for diffraction. Kα1and Kα2 are sufficiently close in wavelength such that a weighted average of the two is used.
  34. 34. X-ray Diffraction Instrumentation  Copper is the most common target material for single-crystal diffraction, with CuKα radiation = 1.5418Å.  These X-rays are collimated and directed onto the sample.  As the sample and detector are rotated, the intensity of the reflected X-rays is recorded.  When the geometry of the incident X-rays impinging the sample satisfies the Bragg Equation, constructive interference occurs and a peak in intensity occurs.  A detector records and processes this X-ray signal and converts the signal to a count rate which is then output to a device such as a printer or computer monitor.  The geometry of an X-ray diffractometer is such that the sample rotates in the path of the collimated X-ray beam at an angle θ while the X-ray detector is mounted on an arm to collect the diffracted X-rays and rotates at an angle of 2θ.  The instrument used to maintain the angle and rotate the sample is termed a goniometer.  For typical powder patterns, data is collected at 2θ from ~5° to 70°, angles that are present in the X-ray scan.
  35. 35. • A continuous beam of X-rays is incident on the crystal • The diffracted radiation is very intense in certain directions • These directions correspond to constructive interference from waves reflected from the layers of the crystal • The diffraction pattern is detected by photographic film How X-ray Diffraction works
  36. 36. NaCl How Diffraction Works: Schematic
  37. 37. NaCl How Diffraction Works: Schematic
  38. 38. Used to determine • Crystal structure • Orientation • Degree of crystalline perfection/imperfections Sample is illuminated with monochromatic radiation • Easier to index and solve the crystal structure because it diffraction peak is uniquely resolved Single Crystal X-ray Diffraction
  39. 39.  A single crystal at random orientations and its corresponding diffraction pattern.  Just as the crystal is rotated by a random angle, the diffraction pattern calculated for this crystal is rotated by the same angle Single Crystal X-ray Diffraction
  40. 40.  More appropriately called polycrystalline X-ray diffraction, because it can also be used for sintered samples, metal foils, coatings and films, finished parts, etc.  Used to determine  phase composition (commonly called phase ID)-what phases are present?  quantitative phase analysis-how much of each phase is present?  unit cell lattice parameters, crystal structure  average crystallite size of nanocrystalline samples  crystallite microstrain and texture  residual stress (really residual strain) X-ray Powder Diffraction
  41. 41. Fundamental Principle of X-ray Powder Diffraction This law relates the wavelength of electromagnetic radiation to the diffraction angle and the lattice spacing in a crystalline sample. These diffracted X-rays are then detected, processed and counted. By scanning the sample through a range of 2θangles, all possible diffraction directions of the lattice should be attained due to the random orientation of the powdered material.  Conversion of the diffraction peaks to d-spacings allows identification of the mineral because each mineral has a set of unique d-spacings. Typically, this is achieved by comparison of d-spacings with standard reference patterns. All diffraction methods are based on generation of X-rays in an X-ray tube. These X-rays are directed at the sample, and the diffracted rays are collected. A key component of all diffraction is the angle between the incident and diffracted rays.
  42. 42. Single crystal Vs. Powder crystal XRD  Although the single crystal and powder crystal XRD patterns essentially contain the same Information, but in the former case the information is distributed in three dimensional space whereas In the latter case the three dimensional data are “compressed” into one dimension
  43. 43. X-ray Powder Diffraction Applications  Characterization of crystalline materials  Identification of fine-grained minerals such as clays and mixed layer clays that are difficult to determine optically  Determination of unit cell dimensions  Measurement of sample purity  Determine of modal amounts of minerals (quantitative analysis)  Characterize thin films samples by:  determining lattice mismatch between film and substrate and to inferring stress and strain  determining dislocation density and quality of the film by rocking curve measurements  measuring superlattices in multilayered epitaxial structures  determining the thickness, roughness and density of the film  make textural measurements, such as the orientation of grains, in a polycrystalline sample
  44. 44. Strength of X-ray Powder Diffraction 1. Powerful and rapid (< 20 min) technique for identification of an unknown mineral 2. In most cases, it provides an unambiguous mineral determination 3. Minimal sample preparation is required 4. XRD units are widely available 5. Data interpretation is relatively straight forward

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