Spectroscopy is broadly described as a field in physics concerned with recording of spectra, ranging from gamma to X-rays, neutrons, UV, visible, NIR, IR, microwaves, radio frequency, ultrasound, acoustic waves, gravitational, etc.

This is a contributed topic on spectroscopy themes and underlying concepts and theories.

• Electrical fields
• magnetic fields
• Electromagnetic fields and waves
• Biot-Savart equations
• Maxwell's equations
• vector calculus in electrostatics
• Vector and scalar potentials
• Kramers-Kronig relations
• Stokes theorem
• Laplace equation
• Poisson equation
• Einstein's GR equations
• Planck's equation
• Polarization
• Polarizability
• Poynting vector
• Reflection spectroscopy (NIR, vis, electron, etc.)
• Transmission spectroscopy (vis/UV, NIR/IR, etc.)
• Polarized IR and Polarized NIR
• Vibrational Circular Dichroism (VCD)
• Absorption spectroscopy (vis/UV, NIR/IR, NMR, EPR/ESR, FMR etc.)
• Spectroscopy and spectrophotometry
• Coherent spectroscopy of atoms and molecules
• Electron spectroscopy (x-ray photoelectron (XPS), Auger electron spectroscopy (AES), and so on)
• EXAFS and X-ray spectroscopy
• Neutron spectroscopy
• M�ssbauer spectroscopy
• Infrared and Raman spectroscopy
• Hyperspectral (NIR, IR, UV/vis) imaging
• microspectroscopy
• Fluorescence Correlation Spectroscopy (FCS)
• Fresnel equations
• Diffraction equations
• Electric dipoles
• Dipole-dipole interactions
• dipole-induced dipole interactions
• Ion-dipole interactions
• London dispersion forces
• Yang-Mills equations
• Yang-Baxter equations
• Quantum Yang-Baxter equations
• Total intermolecular pair potentials
• Optical constants
• Extinction coefficient
• Refraction and reflection coefficients
• Total internal reflection
• Derivation of the Kramers-Kronig relations
• Lorentz model
• AC and DC conductivity
• Displacement
• Skin depth