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 ↓


Electronic Spectroscopy


Electronic spectroscopy is an essential tool in physical chemistry used to study electronic transitions in molecules. It focuses on the absorption and emission of light by electrons in atoms and molecules, providing information about the electronic structure and dynamics of these systems. The field includes a variety of methods, including UV-vis spectroscopy, fluorescence spectroscopy, and photoelectron spectroscopy.

Basic principles

Electronic spectroscopy is based on the quantization of energy levels in molecules. When a molecule absorbs energy, electrons are promoted from a lower energy state to a higher energy state. The energy difference between these states corresponds to the energy of the absorbed light. This can be represented mathematically as:

E = hν = E_2 - E_1

In this formula, E is the energy of the absorbed light, h is the Planck constant, ν is the frequency of the light, E_2 is the energy of the excited state, and E_1 is the energy of the ground state.

E_1 E_2 hν = E_2 - E_1

Electronic transitions involve changes in the distribution of electrons in a molecule, which often affects their chemical behavior. This is important in fields such as photochemistry and materials science, where understanding these transitions can help design better chemical reactions or develop new materials.

Types of electronic spectroscopy methods

UV-visible spectroscopy

UV-Visible Spectroscopy (UV-Vis) measures the absorption of ultraviolet or visible light by molecules. This method is particularly useful for studying conjugated systems, where electrons can easily transition between different delocalized energy states. The wavelength at which maximum absorption occurs provides information about the energy difference between the ground and excited states. For example:

λ_max ≈ 200 - 800 nm

UV-Vis spectroscopy is widely used in the analysis of pigments, biological molecules, and chemical bonding. A typical example is to determine the concentration of a substance in a solution using the Beer-Lambert law:

A = εcl

Here, A is the absorbance, ε is the molar absorptivity, c is the concentration, and l is the path length of the sample cell.

Fluorescence spectroscopy

Fluorescence spectroscopy involves exciting electrons to higher energy levels and then measuring the light emitted as they return to the ground state. This technique is highly sensitive, providing valuable information about molecular environments and processes. The wavelength of the emitted light is usually longer than that of the absorbed light because of energy losses:

λ_em > λ_ex

Applications of fluorescent spectroscopy include studying the dynamics of proteins, nucleic acids, and other biomolecules. By labeling specific components with fluorescent probes, scientists can track interactions and conformations in complex biological systems.

Photoelectron spectroscopy

Photoelectron spectroscopy (PES) investigates the kinetic energy of electrons ejected from a material when irradiated with high-energy photons. This provides detailed information about the electronic structure, particularly the energy of binding electrons in atoms and molecules. The central equation is:

E_kin = hν - E_B

Here, E_kin is the kinetic energy of the ejected electron, hν is the photon energy, and E_B is the binding energy of the electron.

Applications of electronic spectroscopy

The applications of electronic spectroscopy span across various scientific disciplines. In materials science, it helps characterise new materials and explore their electronic properties. In chemistry, it is helpful in reaction monitoring, mechanistic studies and the design of photochemically active compounds. In biology, these techniques are important in studying the structure and dynamics of biomolecules.

Insights into molecular structure and dynamics

Information obtained from electronic spectroscopy can be used to infer molecular structures, such as bond lengths, angles, and electron distributions. Transition energies can also shed light on molecular dynamics, reaction pathways, and energy transfer processes.

Conclusion

Electronic spectroscopy is a cornerstone of physical chemistry, adding to our understanding of light-matter interactions in atoms and molecules. Its wide range of techniques and applications is continually evolving, promising a deeper understanding of chemical and biological systems at the electronic level.


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Electronic Spectroscopy

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