PHD
  1. Inorganic chemistry  1.1. Coordination chemistry  1.1.1. Ligand field theory  1.1.2. Crystal field theory  1.1.3. Molecular Orbital Theory for Coordination Compounds  1.1.4. Stability of Coordination Compounds  1.1.5. Electronic spectra of coordination compounds  1.1.6. Isomerism in Coordination Compounds  1.1.7. Kinetics and mechanism of coordination reactions  1.2. Organometallic Chemistry  1.2.1. Metal Carbonyls  1.2.2. Metal alkyl and aryl  1.2.3. Fischer and Schrock carbonaceans  1.2.4. Oxidative Addition and Reductive Elimination  1.2.5. Metal Hydrides  1.2.6. Catalysis by organometallic compounds  1.2.7. Metallocenes and Sandwich Complexes  1.2.8. CH activation  1.3. Solid state chemistry  1.3.1. Crystal structures and lattices  1.3.2. Band theory and electrical properties  1.3.3. Defects in the crystal  1.3.4. Synthesis of solid state materials  1.3.5. Magnetic and optical properties of solids  1.3.6. Superconductivity  1.3.7. Solid state ionics  1.4. Bio-inorganic chemistry  1.4.1. Metalloproteins and enzymes  1.4.2. Metal ion transport and storage  1.4.3. The role of metals in medicine  1.4.4. Bioinspired catalysis  1.4.5. Metal–DNA interactions  1.4.6. Metal Complexes in Medical Science  1.5. Lanthanides and Actinides  1.5.1. Electronic configuration and oxidation states in lanthanides and actinides  1.5.2. Spectral and Magnetic Properties in Lanthanides and Actinides  1.5.3. Separation and Extraction of Lanthanides and Actinides  1.5.4. Coordination chemistry of f-block elements  1.6. Main Group Chemistry  1.6.1. Chemistry of boron compounds  1.6.2. Chemistry of Silicon and Germanium Compounds  1.6.3. Chemistry of Phosphorus and Sulfur Compounds  1.6.4. Organosilicon chemistry  1.6.5. Noble Gas Chemistry
  2. Organic chemistry  2.1. Reaction mechanism  2.1.1. Nucleophilic substitution reactions  2.1.2. Electrophilic addition and substitution reactions  2.1.3. Elimination reactions  2.1.4. Rearrangement reactions  2.1.5. Radical reactions  2.1.6. Pericyclic Reactions  2.1.7. Photochemical reactions  2.2. Stereoscopic  2.2.1. Chirality and optical activity  2.2.2. Structural analysis  2.2.3. Stereoelectronic effects  2.2.4. Asymmetric synthesis  2.2.5. Dynamic Stereochemistry  2.3. Organometallic Chemistry in Organic Synthesis  2.3.1. Organolithium and organomagnesium reagents  2.3.2. Transition metal catalyzed coupling reactions  2.3.3. Palladium-catalyzed reactions  2.3.4. Olefin Metathesis  2.3.5. Gold and silver catalysis  2.4. Natural products chemistry  2.4.1. Alkaloids and terpenoids  2.4.2. Steroids and Flavonoids  2.4.3. Total synthesis of natural products  2.4.4. Biosynthesis of natural products  2.5. Supramolecular Chemistry  2.5.1. Host-Guest Chemistry  2.5.2. Self-assembly and molecular recognition  2.5.3. Supramolecular Catalysis  2.5.4. Molecular Machines
  3. Physical Chemistry  3.1. Thermodynamics  3.1.1. Laws of Thermodynamics  3.1.2. Chemical Potential and Equilibrium  3.1.3. Statistical thermodynamics  3.1.4. Non-equilibrium thermodynamics  3.2. Quantum Chemistry  3.2.1. Schrödinger equation and its applications  3.2.2. Molecular orbital theory  3.2.3. Density functional theory  3.2.4. Post-Hartree–Fock methods  3.3. Chemical kinetics  3.3.1. Reaction rate theory  3.3.2. Mechanism and rate laws  3.3.3. Catalysis and enzyme kinetics  3.3.4. Reaction dynamics  3.4. Spectroscopy and molecular structure  3.4.1. Infrared Spectroscopy  3.4.2. UV-visible spectroscopy  3.4.3. Nuclear Magnetic Resonance Spectroscopy  3.4.4. Mass Spectrometry  3.4.5. Raman Spectroscopy  3.5. Surface and Colloid Chemistry  3.5.1. Absorption and Catalysis  3.5.2. Surfactants and micelles  3.5.3. Colloidal Stability  3.5.4. Nanomaterials and Interfaces
  4. Analytical chemistry  4.1. Chromatography  4.1.1. Gas Chromatography  4.1.2. High Performance Liquid Chromatography  4.1.3. Thin Layer Chromatography  4.1.4. Ion Chromatography  4.2. Electroanalytical techniques  4.2.1. Voltammetry and Polarography  4.2.2. Conductometry and potentiometry  4.2.3. Colometry  4.3. Spectroscopic Methods  4.3.1. Atomic absorption spectroscopy  4.3.2. Fluorescence Spectroscopy  4.3.3. X-ray diffraction  4.3.4. Electron paramagnetic resonance spectroscopy  4.4. Chemometrics  4.4.1. Data processing and statistical methods  4.4.2. Multidisciplinary analysis  4.4.3. Machine Learning in Analytical Chemistry
  5. Theoretical and Computational Chemistry  5.1. Molecular dynamics simulation  5.2. Quantum chemistry methods  5.3. Computational drug design  5.4. Machine Learning in Chemistry  5.5. Ab initio molecular dynamics
  6. Biophysics and Medicinal Chemistry  6.1. Drug discovery and design  6.2. Enzyme kinetics and inhibition  6.3. Chemical biology approach  6.4. Protein-ligand interactions  6.5. Bioorthogonal chemistry
  7. Materials chemistry  7.1. Polymer chemistry  7.1.1. Polymerization mechanism  7.1.2. Functional Polymers  7.1.3. Biodegradable Polymer  7.1.4. Conducting and semiconducting polymers  7.2. Nano Chemistry  7.2.1. Nanoparticles and nanostructures  7.2.2. Carbon-based nanomaterials  7.2.3. Quantum dots  7.3. Energy and Environmental Chemistry  7.3.1. Battery and Fuel Cell Chemistry  7.3.2. Green chemistry and sustainable materials  7.3.3. Photocatalysis

PHD → Analytical chemistry ↓


Spectroscopic Methods


Spectroscopy is an important method in analytical chemistry, used to study the interaction between matter and electromagnetic radiation. It is a fundamental tool for analyzing the composition and structure of substances. Spectroscopy has evolved considerably, with many techniques available to analyze various properties of substances.

Introduction to spectroscopy

Spectroscopy involves measuring the absorption, emission or scattering of electromagnetic radiation by atoms or molecules. This measurement provides information about the energy levels, structure and dynamics of these entities. The main idea is to monitor the intensity of radiation as a function of wavelength, frequency or energy, which can provide a "spectral fingerprint" for different substances.

Types of spectroscopic methods

There are many types of spectroscopic methods, each suitable for a specific type of analysis. Some of the main types are as follows:

  1. Ultraviolet-visible (UV-Vis) spectroscopy
  2. Infrared (IR) spectroscopy
  3. Raman spectroscopy
  4. Nuclear magnetic resonance (NMR) spectroscopy
  5. Mass spectrometry (MS)
  6. X-ray spectroscopy

Ultraviolet-visible (UV-Vis) spectroscopy

UV-Vis spectroscopy is used to determine the absorption of UV or visible light by a substance. It is widely used to measure the concentration of analytes in solution based on Beer's law:

A = εlc

Where:

  • A is the absorption.
  • ε is the molar absorption capacity.
  • l is the path length of the sample cell.
  • c is the concentration of the compound in the solution.

For example, consider the absorption of light by a colored compound in water. By measuring the absorption at a specific wavelength, one can determine the concentration of this compound. This is particularly useful for studying transition metal complexes or organic compounds containing conjugated systems.

Wavelength (nm)Absorptionλ max

Infrared (IR) spectroscopy

Infrared spectroscopy involves the study of molecular vibrations that occur when IR radiation is absorbed by a substance. It is particularly useful for identifying functional groups and studying molecular structures.

When a molecule absorbs IR radiation, vibrational changes occur in it. The IR spectrum is plotted as a graph of transmittance or absorbance versus wave number (cm -1). Each peak corresponds to a specific vibration in the molecule.

An example of an IR spectroscopy application is to identify organic compounds. Common functional groups such as alcohols, amines, ketones, and carboxylic acids have characteristic absorption peaks.

Wave number (cm -1)Communication (%)Oh Stretch

Raman spectroscopy

Raman spectroscopy is based on the inelastic scattering of light, known as Raman scattering. This spectroscopy is complementary to IR spectroscopy and is particularly useful for studying molecular vibrations in symmetric molecules, which may be weak in the IR region.

In Raman spectroscopy, the shift in the energy of the scattered light gives information about the vibration modes of molecules. It is useful in studying inorganic and organic compounds, biological systems, and materials science.

For example, in the study of carbon materials, Raman spectroscopy can distinguish between different forms of carbon, such as graphite, diamond, and amorphous carbon.

Nuclear magnetic resonance (NMR) spectroscopy

NMR spectroscopy is a powerful technique based on the interaction between nuclear spins and an external magnetic field. This method provides detailed information about the structure, dynamics, reaction state, and chemical environment of molecules.

In a typical NMR experiment, nuclei absorb radio frequency radiation in the presence of a magnetic field. The resulting NMR spectrum is a plot of the intensity of this radiation against frequency.

δ = (ν - ν ref ) / ν ref × 10 6 ppm

Where:

  • δ is the chemical shift in parts per million (ppm).
  • ν is the sampling frequency.
  • νref is the reference frequency.

For example, in the analysis of organic compounds, NMR can provide information about the number of proton environments, the electronic environments, and the connectivity of different groups within the molecule.

Mass spectrometry (MS)

Mass spectrometry is a technique based on measuring the mass-to-charge ratio of ions. This method is used to determine the molecular weight of compounds, identify compounds, and elucidate chemical structures.

In MS, chemical compounds are ionized to produce charged molecules or molecular fragments. Ions are detected by their mass-to-charge ratio (m/z).

In a typical mass spectrum, the x-axis represents m/z values, while the y-axis represents the relative abundance of the detected ions. Key features include the molecular ion peak and the fragmentation pattern.

Mass spectrometry is widely used in organic and inorganic chemistry, biochemistry, and environmental analysis. For example, in drug development, MS helps to identify and quantify potential drug candidates.

X-ray spectroscopy

X-ray spectroscopy is a group of techniques used to determine the elemental composition, electronic structure, and chemical bonding of substances using X-ray radiation.

Two common types are X-ray fluorescence (XRF) and X-ray photoelectron spectroscopy (XPS). XRF is used for elemental analysis, while XPS provides information about the chemical state and surface structure.

The analysis often involves generating X-rays, which excite core electrons in atoms. Subsequent measurements of the X-ray light emitted during relaxation reveal the structure and chemical state.

An example of X-ray spectroscopy application is in materials science for the study of metal alloys and semiconductor materials.

Conclusion

Spectroscopic methods are indispensable in modern analytical chemistry, providing detailed insight into the compositional and structural aspects of materials. Each technique has its own unique advantages and specific applications, making them invaluable to researchers across a variety of scientific disciplines. As technology advances, the capabilities of these spectroscopic methods continue to grow, providing even more powerful tools for scientific discovery.


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Spectroscopic Methods

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