Tools of the Trade: Common Characterization Techniques in Nanomaterial Synthesis
- 1. Tools of the Trade Advancements in Nanotechnology
- 2. Common Nano Characterization Techniques Spectroscopy • Fourier Transform Infrared Spectroscopy (FT-IR) • X-ray Photoelectron Spectroscopy (XPS) • Auger Electron Spectroscopy (AES) • X-ray Diffraction (XRD) Microscopy • Atomic Force Microscopy (AFM) • Scanning Tunneling Microscopy (STM) • Transmission Electron Microscopy (TEM) • Scanning Electron Microscopy (SEM)
- 3. Fourier Transforms (FT) and Advancement of Analytical Techniques Image and information reproduced from https://chem.rutgers.edu/images/murali/coursematerials/Chem_542_Spring2010_Lecture_3.pdf Key advancements in mathematics – Fourier Transform discovered by J.W. Cooley and J.W. Tukey in 1965
- 4. 1. Emission of Radiation 2. Absorption of Radiation 3. Scattering of Radiation 4. Refraction of Radiation 5. Diffraction of Radiation 6. Rotation of Radiation 7. Electrical Potential 8. Electrical Current 9. Electrical Resistance 10. Mass-to-charge Ratio 11. Reaction Rate 12. Thermal Properties 13. Mass 20 μm vs Electronic Image Diffraction of Radiation Types of Signals
- 5. Signal carries information about the analyte that is of interest to us. Noise is made up of extraneous information that is unwanted because it degrades the accuracy and precision of an analysis Signal-to-Noise Ratio S/N = (mean)/(Standard deviation) = Signal-to-noise (S/N) is much more useful figure of merit than noise alone for describing the quality of an analytical method. The magnitude of the noise is defined as the standard deviation s of numerous measurements, and the signal is given by the mean x of the measurements. S/N is the reciprocal of the relative standard deviation. S/N < 2 or 3 impossible to detect a signal. A x s RSD 1 Instrumental Signals and Noise
- 6. Fourier Transform Infrared Spectroscopy (FTIR) • In 1881, Albert Michelson invented the interferometer • Known as the Michelson interferometer • Simple technique capable of providing high-resolution quantitative and qualitative analysis • Detection of functional groups (must have a dynamic dipole) • Sample can be in a solid, liquid, or gas state • Acquires broadband Near InfraRed (NIR) to Far InfraRed (FIR) spectra • Infrared spectra are obtained by collecting an interferogram of a sample signal using an interferometer and performing a Fourier Transform (FT) on the interferogram to obtain the spectrum. • Key advancements in mathematics: • Multiplex (Fellgett) Advantage • The Throughput Advantage (called the Jacquinot Advantage) • Wide array of applications, from monitoring processes to identifying compounds to determining components in a mixture. Typical Michelson Interferometer Setup
- 7. Fourier Transform Infrared Spectroscopy Michelson Interferometer
- 8. X-ray Photoelectron Spectroscopy (XPS) • In 1967, Siegbahn published a comprehensive study of XPS • Based on the photoelectric effect (Heinrich Rudolf Hertz in 1887) • Surface-sensitive quantitative technique (depth of 2 to 5 nanometers) • Can give chemical state, and the overall electronic structure and density of the electronic states • Uses photoionization and energy-dispersive analysis of the emitted photoelectrons to establish the composition and electronic state of a sample. • Sample type: Usually solid since UHV is required (< 10-8 torr) • Single generated: Photo emitted electrons (< 1.5 kV) • Detector: Electron Energy Analyzer (< 0 to 1.5 kV). Electrons escape from or 70 to 110 Angstroms – the very top surface of the sample. • Wide field of application. Inorganic compounds, metal alloys, polymers, elements, catalysts, glasses, ceramics, paints, papers, inks, woods, plant parts, makeup, teeth, bones, medical implants, bio- materials, coatings, viscous oils, glues, ion-modified materials, and many others Typical XPS Spectrometer Setup
- 9. X-ray Photoelectron Spectroscopy (XPS) Typical XPS Spectrometer Setup
- 10. X-ray Diffraction (XRD) Spectrscopy • In 1914, Max von Laue discovered X-ray diffraction by crystals • Capable of determining a sample's composition or crystalline structure • Sample type: Usually solid crystals but polymers that have crystalline regions can be analyzed • No vacuum is required • Detection of X-ray diffraction patterns • For very small crystal sizes, it can determine sample composition, crystallinity, and phase purity. • Operates by sending X-ray beams through the sample and monitoring the angle of diffraction due to the spacing of atoms in a molecule. • Primarily used for phase identification of a crystalline material and can provide information on unit cell dimensions. X-ray Diffractometer Setup
- 11. X-ray Diffraction (XRD) Spectrscopy X-ray Diffractometer Setup 0 250 500 750 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 2 2 0 2 0 0 1 1 1 2 Theta (Degree) Intensity (arb. units) CuNi Bimetallic nanoparticles
- 12. Scanning Tunneling Microscopy (STM) • Scanning probe microscopes started with the original invention of the STM in 1981. Gerd Binnig and Heinrich Rohrer developed the first STM while working at IBM Zurich Research Laboratories in Switzerland • Works by scanning a very sharp metal wire tip over a surface. STM tips have one atom at the tip and can resolve individual atoms giving extremely high surface accuracy (imaging at extremely small scales) • Operates using several principles – quantum mechanical effect of tunneling, the piezoelectric effect, and feedback loops – to produce a topographical image • Major advantage: Captures atom by atom with ultra-high resolution, without the use of electron beams or light • Major disadvantage: samples must be conductive limiting the type of materials for analysis Typical STM Microscope Setup
- 13. Atomic Force Microscopy (AFM) • In 1985, IBM scientists Binnig, Quate, and Gerber invented the AFM Microscope. Invented to replace the shortcomings of STM. • AFM has three major abilities: force measurement, topographic imaging, and manipulation. • Three modes of operation: Contact, Tapping, and Noncontact • Detection: Depends on the mode of operation. In general, monitors the change in the surface topography and can be used to monitor changes in force along the surface • Typically use a laser beam deflection system where a laser is reflected from the back of the reflective AFM lever onto a position-sensitive detector • AFM has the advantage of imaging almost any surface type, including polymers, ceramics, composites, glass, and biological samples. • Widely used in the advancement of nanotechnology Typical AFM Microscope Setup
- 14. Scanning Tunneling Microscopy (STM)
- 15. Atomic Force Microscopy (AFM) Typical AFM Microscope Setup
- 16. Transmission Electron Microscopy (TEM) • In 1931, TEM was demonstrated by Max Knoll and Ernst Ruska (first commercial TEM was in 1939) • Transmits a beam of high-energy electrons transmitted through the solid to image the internal structure of solids • Solids must be sufficiently thin to allow the transmittance of electrons • Other techniques must be used to thin sample areas of interest such as ion milling, electropolishing, focused ion beams, etc • Detects energy-loss electrons and characteristic X-rays • Widely used in areas of cancer research, virology, materials science, nanotechnology, semiconductor research, and beyond • Major drawbacks: Requires large spaces for operation and higher purchase price tags high-end research grade TEM (approx. $10 million) Typical TEM Microscope Setup
- 17. Transmission Electron Microscopy (TEM) Typical TEM Microscope Setup
- 18. Scanning Electron Microscopy (SEM) • The invention of the SEM principle cannot be pinpointed to only one contributor in history. However, it was the German scientist Max Knoll who built the first “scanning microscope” in 1935 • Known as the Michelson interferometer • Scans a sample with an electron beam to produce a magnified image for analysis • Detection: Secondary and primary scattered electrons. • Sample must be conductive or coated with a conductive layer, fit into the standard TEM grid holder, and should be less than 1 mm in height. Samples are supported either by a TEM grid or LVEM5 SEM stubs. • Vacuum required (> 10-4 Torr) • Allow analysis of surface features at 5 to 300,000X magnification, providing high-quality, depth-of-field images. • Highly used in the determination and characterization of materials failure analysis, dimensional analysis, contaminant analysis, particle analysis, and reverse engineering Typical SEM Microscope Setup
- 19. Scanning Electron Microscopy (SEM) Typical SEM Microscope Setup