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Chemistry LibreTexts

Electronic Spectroscopy

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  • Electron spectroscopy is an analytical technique to study the electronic structure and its dynamics in atoms and molecules. In general an excitation source such as x-rays, electrons or synchrotron radiation will eject an electron from an inner-shell orbital of an atom.

    • Circular Dichroism
      Circular Dichroism, an absorption spectroscopy, uses circularly polarized light to investigate structural aspects of optically active chiral media. It is mostly used to study biological molecules, their structure, and interactions with metals and other molecules.
    • Electronic Spectroscopy: Application
      Electronic Absorption and Fluorescence spectroscopy are both analytical methods that center around the idea that when one perturbs a known or unknown solution with a spectrum of energetic photons, those photons that have the correct energy to interact with the molecules in solution will do so, and those molecules under observation will always interact with photons of energies characteristic to that molecule.
    • Electronic Spectroscopy: Interpretation
      Electronic Spectroscopy relies on the quantized nature of energy states. Given enough energy, an electron can be excited from its initial ground state or initial excited state (hot band) and briefly exist in a higher energy excited state. Electronic transitions involve exciting an electron from one principle quantum state to another. Without incentive, an electron will not transition to a higher level. Only by absorbing energy, can an electron be excited.
    • Electronic Spectroscopy Basics
      Explains the origin of UV-visible absorption spectra, how they are measured, and how they can be used in the analysis of organic compounds.
    • Fluorescence and Phosphorescence
      Fluorescence and phosphorescence are types of molecular luminescence methods. A molecule of analyte absorbs a photon and excites a species. The emission spectrum can provide qualitative and quantitative analysis. The term fluorescence and phosphorescence are usually referred as photoluminescence because both are alike in excitation brought by absorption of a photon.
    • Jablonski diagram
      A Jablonski diagram is basically an energy diagram, arranged with energy on a vertical axis. The energy levels can be quantitatively denoted, but most of these diagrams use energy levels schematically. The rest of the diagram is arranged into columns. Every column usually represents a specific spin multiplicity for a particular species. However, some diagrams divide energy levels within the same spin multiplicity into different columns.
    • Metal to Ligand and Ligand to Metal Charge Transfer Bands
      In the field of inorganic chemistry, color is commonly associated with d–d transitions. If this is the case, why is it that some transition metal complexes show intense color in solution, but possess no d electrons? In transition metal complexes a change in electron distribution between the metal and a ligand gives rise to charge transfer (CT) bands when performing Ultraviolet-visible spectroscopy experiments. A brief introduction to electron transfer reactions and Marcus-Hush theory is given.
    • Radiative Decay
      Spontaneous emission is the process in which a quantum mechanical system (such as an atom, molecule or subatomic particle) transitions from an excited energy state to a lower energy state (e.g., its ground state) and emits a quantum in the form of a photon.
    • Selection Rules for Electronic Spectra of Transition Metal Complexes
      The Selection Rules governing transitions between electronic energy levels.
    • Spin-orbit Coupling
      Spin-orbit coupling refers to the interaction of a particle's "spin" motion with its "orbital" motion.
    • Two-photon absorption
      Two-photon absorption is one of a variety of two-photon processes. In this specific process, two photons are absorbed by a sample simultaneously. Neither photon is at resonance with the available energy states of the system, however, the combined frequency of the photons is at resonance with an energy state.