Nanoparticles Characterization Techniques PDF

Vs By Dr. Bishoy Samy Fall 2024/2025  COURSE CONTENTS ❑ Defining nanoparticles, nanocrystals and nanomaterials ❑ Bonding and band structure ❑ Characterization of nanomaterials ❑ Top- Down fabrication of nanomaterials ❑ Bottom-up (chemical) fabrication of nanomaterials and their self...

Vs By Dr. Bishoy Samy Fall 2024/2025  COURSE CONTENTS ❑ Defining nanoparticles, nanocrystals and nanomaterials ❑ Bonding and band structure ❑ Characterization of nanomaterials ❑ Top- Down fabrication of nanomaterials ❑ Bottom-up (chemical) fabrication of nanomaterials and their self assembly ❑ Properties of nanocrystals ❑ Examples of applications of nanocrystals and nanoparticles  NANOPARTICLES CHARACTERIZATION TECHNIQUES Microscopy techniques SEM TEM – HRTEM – Cryo TEM In-situ techniques (ex, environmental TEM) Surface probing techniques Scanning tunneling microscope Atomic force microscope Spectroscopy Techniques Absorption Luminescence IR Raman X Dynamic light scattering, and time-resolved spectroscopy X Mass Spectrometry X SIMS X X-ray spectroscopy techniques XRD, XPS Nuclear Magnetic Resonance (NMR) Spectroscopy X ELECTROMAGNETIC SPECTROSCOPY TECHNIQUES ELECTROMAGNETIC SPECTROSCOPY TECHNIQUES In spectrophotometry, several processes occur after the material absorbs energy; these are changes in the electronic energy, vibrational and rotational relaxations, intersystem crossings, as well as internal. Owing to the quantum nature of molecules, their energy distribution at any given moment can be defined as the sum of energy terms: Visible, UV electromagnetic radiations ELECTROMAGNETIC SPECTROSCOPY TECHNIQUES ELECTROMAGNETIC SPECTROSCOPY TECHNIQUES IR Microwave Thermal ELECTROMAGNETIC SPECTROSCOPY TECHNIQUES UV-Visible Spectroscopy Electromagnetic Photoluminescence Spectroscopy Spectroscopy Infrared Spectroscopy ELECTROMAGNETIC SPECTROSCOPY TECHNIQUES UV-visible spectroscopy  Widely utilized to quantitatively characterize organic and inorganic nanosized molecules.  A sample is irradiated with electromagnetic waves in the ultraviolet and visible ranges and the absorbed light is analyzed through the resulting spectrum. ELECTROMAGNETIC SPECTROSCOPY TECHNIQUES UV-visible spectroscopy ELECTROMAGNETIC SPECTROSCOPY TECHNIQUES UV-visible spectroscopy  It can be employed to identify the constituents of a substance, determine their size and concentrations, and to identify functional groups in molecules. ELECTROMAGNETIC SPECTROSCOPY TECHNIQUES UV-visible spectroscopy ELECTROMAGNETIC SPECTROSCOPY TECHNIQUES Photoluminescence Spectroscopy ELECTROMAGNETIC SPECTROSCOPY TECHNIQUES Photoluminescence Spectroscopy  Concerns monitoring the light emitted from atoms or molecules after they have absorbed photons.  Absorption, Nonradiative relaxation, and luminescence.  Suitable for materials that exhibit photoluminescence (organic or inorganic). ELECTROMAGNETIC SPECTROSCOPY TECHNIQUES Infrared Spectroscopy  Popular characterization technique in which a sample is placed in the path of an IR radiation source and its absorption of different IR frequencies is measured.  IR photons energies, in a range between 1 to 15 kcal/mol, are insufficient to excite electrons to higher electronic energy states, but transitions in vibrational energy states.  These states are associated with a molecule’s bonds, and consequently each molecule has its own unique signatures. ELECTROMAGNETIC SPECTROSCOPY TECHNIQUES Infrared Spectroscopy  Popular characterization technique in which a sample is placed in the path of an IR radiation source and its absorption of different IR frequencies is measured. ELECTROMAGNETIC SPECTROSCOPY TECHNIQUES Infrared Spectroscopy  These states are associated with a molecule’s bonds, and consequently each molecule has its own unique signatures. ELECTROMAGNETIC SPECTROSCOPY TECHNIQUES Infrared Spectroscopy  Useful to identify the functional groups attached to NPs surface and consequently the organic ligands attached to nanoparticles surface.  Because IR spectroscopy is quantitative, the number of a type of bond may be determined.  X-RAY SPECTROSCOPY TECHNIQUES X-Ray Diffraction (XRD):  XRD involves monitoring the diffraction of X-rays after they interact with the sample. It is a crystallographic technique used for identifying and quantifying various crystalline phases present in solid materials and powders.  In XRD the crystal structure can be determined as well as the size of grains and nanoparticles.  When X-rays are directed at a regular crystalline sample, a proportion of them are diffracted to produce a pattern. From such a pattern the crystal phases can be identified by comparison to those of internationally recognized databases (such as International Center of Diffraction Data - ICDD). X-RAY SPECTROSCOPY TECHNIQUES X-Ray Diffraction (XRD): X-RAY SPECTROSCOPY TECHNIQUES X-Ray Diffraction (XRD): X-RAY SPECTROSCOPY TECHNIQUES X-Ray Diffraction (XRD):  The crystal to be characterized by XRD has a space lattice with an ordered three-dimensional distribution (cubic, rhombic, etc.) of atoms. These atoms form a series of parallel planes separated by a distance d, which varies according to the nature of the material.  For any crystal, planes have their own specific d- spacing. When a monochromatic X-ray beam with wavelength λ is irradiated onto a crystalline material with spacing d, at an angle θ, diffraction occurs only when the distance traveled by the rays reflected from successive planes differs by an integer number n of wavelengths to produce constructive interference. Such constructive interference patterns only occur when incident angles fulfill the Bragg condition.  X-RAY SPECTROSCOPY TECHNIQUES X-Ray Diffraction (XRD):  By varying the angle θ, the Bragg Law condition is satisfied for different d-spacings in polycrystalline materials. Plotting the angular positions versus intensities produces a diffraction pattern, which is characteristic of the sample. fcc gold NPs X-RAY SPECTROSCOPY TECHNIQUES X-Ray Diffraction (XRD):  Scherrer equation: to get information about the size of the NP ( grain size)  t: Crystal thickness  K: Constant that depends on the crystallite shape  B: Full width at half maximum of the broadened peak. X-RAY SPECTROSCOPY TECHNIQUES X-Ray Diffraction (XRD):  Limitations:  The materials must have ordered structure, and it cannot be used directly to study amorphous materials.  Mixtures of phases that have low symmetry are difficult to differentiate between because of the larger number of diffraction peaks.  XRD is not so useful for very small NPs (for ex, 5 nm). In that case, other X-rays techniques are required.  X-RAY SPECTROSCOPY TECHNIQUES X-Ray Photoelectron Spectroscopy (XPS):  XPS can quantify the chemical and electronic states of the elements within the first few atomic layers of a surface.  It can be used to identify elements, their chemical bonds, and hence the chemical composition and empirical formulae (ex, differentiate between metal oxides, sulfides, carbides, …. etc).  X-RAY SPECTROSCOPY TECHNIQUES X-Ray Photoelectron Spectroscopy (XPS):  The XPS is based on the photoelectric effect, in which X- rays cause photoelectrons to be ejected from a surface. X-RAY SPECTROSCOPY TECHNIQUES X-Ray Photoelectron Spectroscopy (XPS):  The X-rays strike the sample surface and interact with the atomic electrons in the sample, via photon absorption.  The focused X-ray beam incoming to the sample has energy of approximately 1.5 keV while the reflected photoelectrons have smaller energies that can be measured (kinetic energy).  The binding energy of the reflected electrons can be measured as the difference between those 2 energies and is plotted as a function of their intensities (numbers). X-RAY SPECTROSCOPY TECHNIQUES X-Ray Photoelectron Spectroscopy (XPS):  The acquired spectrum is compared with spectra from known databases.  The peak positions and shapes correspond to the material’s electronic configuration, and therefore elements and compounds show their own unique characteristic peaks. X-RAY SPECTROSCOPY TECHNIQUES X-Ray Photoelectron Spectroscopy (XPS):  Ex, XPS for Zn0.67Cu0.33O X-RAY SPECTROSCOPY TECHNIQUES X-Ray Photoelectron Spectroscopy (XPS):  Main limitation:  XPS is limited to just the first 5-10 nm beneath the surface despite the incoming X-rays being able to penetrate microns into the surface.  This is because the ejected electrons must travel through the sample and yet retain enough energy to reach and excite the detector. Only electrons that are emitted by atoms near the surface have a chance to leave the sample. X-RAY SPECTROSCOPY TECHNIQUES X-Ray Photoelectron Spectroscopy (XPS):  Advanced technique to resolve this limitation:  When the XPS instrument is combined with ion beam sputtering, atomic layers can be continuously removed from the surface. After sputtering, the XPS may be performed once again on these layers, and as a result compositional depth profiles can be obtained down to a few micrometers. X-RAY SPECTROSCOPY TECHNIQUES X-Ray Photoelectron Spectroscopy (XPS):  Other limitations:  As XPS involves monitoring emitted photoelectrons, the experiments must be conducted under ultra high vacuum and therefore the sample should not outgas (non-volatile).  Furthermore, exposure to the X-ray beam can damage certain materials, mainly organic molecules and polymers, and they may degrade during the measurement (destructive technique).