Graduate
  1. Physical Chemistry  1.1. Thermodynamics  1.1.1. Laws of Thermodynamics  1.1.2. Enthalpy and heat capacity  1.1.3. Entropy and free energy  1.1.4. Phase Equilibrium  1.1.5. Statistical thermodynamics  1.1.6. Thermodynamic cycle  1.1.7. Fugacity and activity  1.2. Quantum Chemistry  1.2.1. Principles of quantum mechanics  1.2.2. Schrödinger Equation  1.2.3. Particle in a box  1.2.4. Operators and eigenvalues  1.2.5. Atomic orbitals  1.2.6. Molecular orbital theory  1.2.7. Perturbation theory  1.2.8. Valence bond theory  1.2.9. Hybridization and chemical bonding  1.3. Chemical kinetics  1.3.1. Rate laws and reaction mechanisms  1.3.2. Collision theory  1.3.3. Transition state theory  1.3.4. Enzyme Kinetics  1.3.5. Chain Reactions and Polymerization  1.3.6. Photochemical reactions  1.4. Statistical mechanics  1.4.1. Partitioning functions  1.4.2. Molecular distribution functions  1.4.3. Boltzmann Distribution  1.4.4. Bose–Einstein and Fermi–Dirac statistics  1.5. Spectroscopy  1.5.1. Rotational Spectroscopy  1.5.2. Vibrational Spectroscopy  1.5.3. Electronic Spectroscopy  1.5.4. Nuclear magnetic resonance spectroscopy  1.5.5. Mass Spectrometry  1.5.6. Raman Spectroscopy  1.5.7. Electron paramagnetic resonance spectroscopy  1.6. Surface and colloidal chemistry  1.6.1. Absorption isotherm  1.6.2. Surface tension and wetting  1.6.3. Colloidal Stability  1.6.4. Catalysis  1.6.5. Emulsions and micelles  1.7. Electrochemistry  1.7.1. Nernst equation  1.7.2. Electrochemical cells  1.7.3. Conductivity and mobility  1.7.4. War  1.7.5. Fuel cells  1.7.6. Electrolysis
  2. Organic chemistry  2.1. Reaction mechanism  2.1.1. Nucleophilic substitution reactions  2.1.2. Electrophilic addition reactions  2.1.3. Elimination reactions  2.1.4. Rearrangement reactions  2.1.5. Radical reactions  2.1.6. Pericyclic reactions  2.2. Spectroscopy and structural determination  2.2.1. UV-Vis Spectroscopy  2.2.2. IR Spectroscopy  2.2.3. NMR Spectroscopy  2.2.4. Mass Spectrometry  2.2.5. X-ray crystallography  2.3. Stereoscopic  2.3.1. Chirality and optical activity  2.3.2. Structural analysis  2.3.3. Geometrical isomerism  2.3.4. Dynamic Stereochemistry  2.4. Organometallic Chemistry  2.4.1. Organolithium and organomagnesium reagents  2.4.2. Palladium-catalyzed cross-coupling reactions  2.4.3. Transition Metal Complexes  2.4.4. Metal–carbon bond  2.5. Polymer chemistry  2.5.1. Polymerization mechanism  2.5.2. Polymer Characteristics  2.5.3. Biodegradable Polymer  2.5.4. Conducting polymer  2.5.5. Supramolecular polymers  2.6. Medicinal chemistry  2.6.1. Drug design and development  2.6.2. Pharmacokinetics and pharmacodynamics  2.6.3. Structure-activity relationships  2.6.4. Molecular docking and drug screening
  3. Inorganic chemistry  3.1. Coordination chemistry  3.1.1. Crystal field theory  3.1.2. Ligand field theory  3.1.3. Spectrochemical Series  3.1.4. Chelation and stability  3.2. Organometallic Chemistry  3.2.1. Metal Carbonyls  3.2.2. Catalysis by organometallic complexes  3.2.3. Metallocenes  3.3. Bio-inorganic chemistry  3.3.1. Metalloproteins and enzymes  3.3.2. The role of metals in biological systems  3.3.3. Metal ion transport and storage  3.4. Solid state chemistry  3.4.1. Crystal Structures  3.4.2. Band theory of solids  3.4.3. Superconductors  3.4.4. Defects in the crystal  3.5. Lanthanides and Actinides  3.5.1. Electronic configuration in lanthanides and actinides  3.5.2. Coordination chemistry of the lanthanides  3.5.3. Magnetic Properties of Lanthanides
  4. Analytical chemistry  4.1. Chromatography  4.1.1. Gas Chromatography  4.1.2. High Performance Liquid Chromatography  4.1.3. Thin Layer Chromatography  4.2. Spectroscopic Techniques  4.2.1. Atomic absorption spectroscopy  4.2.2. X-ray diffraction  4.2.3. Inductively coupled plasma spectroscopy  4.3. Electroanalytical methods  4.3.1. Potentiometry  4.3.2. Voltammetry  4.3.3. Colometry  4.4. Mass Spectrometry  4.4.1. Ionization Technique  4.4.2. Fragmentation Pattern  4.5. Chemometrics  4.5.1. Multidisciplinary analysis  4.5.2. Machine Learning in Chemistry
  5. Theoretical and Computational Chemistry  5.1. Molecular dynamics simulation  5.1.1. Force fields and energy minimization  5.1.2. Monte Carlo simulation in molecular dynamics simulations  5.2. Quantum chemical methods  5.2.1. Hartree–Fock theory  5.2.2. Density functional theory  5.2.3. Semi-empirical methods  5.3. Computational drug design  5.3.1. Molecular Docking  5.3.2. QSAR Modeling  5.3.3. Virtual Screening
  6. Biochemistry  6.1. Enzyme Kinetics  6.1.1. Michaelis-Menten kinetics  6.1.2. Inhibition mechanism  6.2. Metabolism and Bioenergetics  6.2.1. Glycolysis  6.2.2. Citric acid cycle  6.2.3. Electron transport chain  6.3. molecular Biology  6.3.1. DNA replication and repair  6.3.2. Protein synthesis  6.3.3. Gene Regulation  6.4. Structural Biochemistry  6.4.1. Protein Folding  6.4.2. Membrane Biophysics
  7. Environmental Chemistry  7.1. Atmospheric Chemistry  7.1.1. Greenhouse gases  7.1.2. Ozone depletion  7.1.3. Air pollutants and smoke  7.2. Water Chemistry  7.2.1. pH and water hardness  7.2.2. Wastewater treatment  7.2.3. Aquatic Chemistry  7.3. Soil Chemistry  7.3.1. Heavy metal contamination  7.3.2. Soil pH and Buffering  7.3.3. Nutrient cycling  7.4. Toxicology and Chemical Safety  7.4.1. Toxicokinetics  7.4.2. Risk Assessment in Toxicology and Chemical Safety in Environmental Chemistry  7.4.3. Effects of pollutants on the environment

Graduate → Physical Chemistry ↓


Spectroscopy


Spectroscopy is a fundamental tool used in physical chemistry to study the interaction between matter and electromagnetic radiation. This technique is valuable in identifying the structure and composition of molecules. By analyzing the spectrum of a substance, one can infer various properties such as energy levels, molecular motion, and even the environment surrounding the substance within the sample.

Introduction to spectroscopy

Spectroscopy involves the study of how light interacts with matter. The term "light" covers a wide range of electromagnetic radiation, from gamma rays to radio waves. These interactions provide a great deal of information about the atomic and molecular structure of substances. Basically, when matter absorbs or emits electromagnetic radiation, it does so at different energy levels, which can be observed as a spectrum.

Electromagnetic spectrum

The electromagnetic spectrum includes various types of radiation, each with its own characteristic wavelengths and frequencies. The spectrum can be divided into several regions, which are ordered by wavelength:

  • Gamma Rays
  • X-rays
  • Ultraviolet (UV) radiation
  • Visible light
  • Infrared (IR) radiation
  • Microwave
  • Radio waves

The interaction of these different regions of the electromagnetic spectrum with matter forms the basis of various spectroscopic techniques. For example, UV-visible spectroscopy focuses on the UV and visible regions, while IR spectroscopy focuses on the infrared region.

Fundamentals of spectroscopy

At the core of spectroscopy are transitions between different energy levels within atoms or molecules. When a photon of electromagnetic radiation is absorbed by a molecule, it can be promoted from a lower energy state to a higher energy state. This change can be described by the equation:

ΔE = E_high - E_low

Here, ΔE is the energy difference between the high and low states, corresponding to the energy of the absorbed photon. According to Planck's equation, the energy of a photon is related to its frequency (ν) and wavelength (λ) by this relation:

E = hν = hc/λ

where h is the Planck constant, ν is the frequency of the radiation, c is the speed of light, and λ is the wavelength. This relation forms the basis for identifying the type of transition occurring during spectroscopic measurements.

Types of spectroscopy

A variety of spectroscopic methods have been developed to investigate different types of molecular and atomic interactions. Each technique focuses on a particular interaction characterized by the energy of the electromagnetic radiation being used:

Ultraviolet-visible (UV-Vis) spectroscopy

UV-Vis spectroscopy measures the absorption of light in the UV and visible regions of the electromagnetic spectrum. This technique is often used to determine the concentration of a substance in solution using the Beer-Lambert law:

A = εlc

where A is the absorbance, ε is the molar absorbance, l is the path length of the cuvette, and c is the concentration of the solution.

incident light Sample transmitted light

Infrared (IR) spectroscopy

IR spectroscopy is used to investigate vibrational and rotational transitions in molecules, providing information about molecular structure. Functional groups within a molecule absorb specific frequencies of IR radiation, resulting in a spectrum that acts like a molecular fingerprint.

Molecule

IR spectroscopy is highly effective in characterizing functional groups such as carbonyl, hydroxyl, and alkene due to their characteristic absorption peaks.

Nuclear magnetic resonance (NMR) spectroscopy

NMR spectroscopy is based on the absorption of radiofrequency radiation by nuclei in a magnetic field. The resulting spectrum provides valuable information about the environment of the nucleus (usually hydrogen or carbon), helping to elucidate molecular structure and dynamics.

Magnetic Field radio waves

Mass spectrometry (MS)

Although not a form of spectroscopy by the strict definition, mass spectrometry has similar principles. This technique measures the mass-to-charge ratio of ions. By ionizing chemical compounds and analyzing their mass spectra, one can determine molecular weight and structure.

Applications of spectroscopy

Spectroscopy has a wide range of applications in diverse areas of research and industry:

Chemical analysis

Spectroscopy provides a powerful method for qualitative and quantitative chemical analysis. For example, UV-Vis spectroscopy is used to measure the concentration of substances in solution, while FTIR (Fourier-transform infrared) spectroscopy identifies organic and inorganic compounds based on their functional groups.

Biochemistry and medicine

NMR spectroscopy plays an important role in elucidating the structure of biomolecules such as proteins and nucleic acids. Additionally, MRI (magnetic resonance imaging), derived from NMR principles, is an important tool in medical diagnosis.

Environmental science

Spectroscopy is used in the monitoring of environmental pollutants. For example, spectroscopy methods are used to detect the amount of metals and organic pollutants in water, soil, and air samples.

Conclusion

Spectroscopy is an essential technique in physical chemistry and related fields, providing detailed information about the structural and dynamic properties of matter. Its ability to provide precise, detailed information makes it an invaluable tool for researchers from a variety of disciplines.


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Spectroscopy

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