Electronic spectroscopy

Electronic spectroscopy studies how atoms and molecules absorb, emit, or scatter light during transitions between electronic energy levels, commonly in the ultraviolet and visible regions.

Electronic transition: A change in an atom or molecule from one electronic energy state to another. These changes generate the spectral features measured by electronic spectroscopy.
Electromagnetic radiation: Energy propagated through space as oscillating electric and magnetic fields. Ultraviolet and visible radiation supplies the photons that drive many electronic transitions.
Ultraviolet–visible spectroscopy: An absorption spectroscopy method that measures ultraviolet and visible light absorbed by a sample. It is the most common laboratory technique based on electronic absorption.
Vibrational spectroscopy: Spectroscopy that probes transitions between vibrational energy levels, commonly using infrared or Raman methods. It probes molecular bond vibrations rather than primarily electronic energy changes.
Hydrogen spectral series: Groups of hydrogen emission lines corresponding to electron transitions between quantized atomic energy levels. The series provide a canonical example of discrete electronic emission spectra.
Beer–Lambert law: A relation connecting light absorbance to the concentration of an absorbing species and the distance light travels through it. It converts measured absorption into quantitative concentration estimates.
Quantum state: A mathematical description of the properties and possible measurement outcomes of a quantum system. Electronic spectroscopy compares the energies and populations of quantum states.
Fluorescence spectroscopy: A method that measures light emitted by a sample after optical excitation. It detects electronic emission with high sensitivity in suitable samples.
Nuclear magnetic resonance spectroscopy: Spectroscopy that measures transitions between nuclear spin states in a magnetic field. Its transitions concern nuclear spins, not electronic excitation by ultraviolet or visible photons.
Sodium D lines: A prominent pair of yellow sodium emission lines near 589 nanometres. Their sharp atomic transitions illustrate how electronic spectra identify elements.

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