With c as the speed of light, which in a vacuum is c 0= 2.99793 x 1010 cm s -1. Wavelength and frequency are correlated through the following equation: The typical unit is oscillations per second (s -1), or Hz. The frequency ν describes the number of oscillations of the electric (or magnetic) radiation vector per unit of time. The energy E (in kJ/mol or eV) is related to frequency ν or wavelength λ according to the equation E = hν = hc/λ, where h is the Planck constant (6.626 x 10 -34 Js) and c is the speed of light in vacuum.Įlectromagnetic radiation can also be characterized by its wavelength λ with the base unit m, but typically expressed in µm or nm.ġ µm = 10 -6 m = 10 -4 cm = 10 -3 mm = 10 3 nm Parameters and Unitsĭepending on the application either energies, wavelengths, frequencies, or wavenumbers are used. 
Įnergy differences between ground and excited energy levels cover a wide range of the electromagnetic spectrum from radio waves to gamma rays, a wide range of transitions, such as nuclear spin level transitions, vibrations of molecular groups or electron transitions. However, they scatter the higher-energy blue wavelengths more effectively than the red wavelengths, so the sky looks blue. When the sunlight passes through the atmosphere the gas molecules in the atmosphere scatter the sunlight, which is breaking up into its parts. Red light has a long wavelength and a lower energy, whereas blue light has a short wavelength and a higher energy. Different colors of light have different energies or wavelengths. All these processes take place when the incident radiation induces changes in energy levels, which can be of electronic, vibrational or nuclear nature.Īn example for the scattering process is the interaction of sunlight with the atmosphere: Sunlight consists of all the colors of the electromagnetic spectrum: red, orange, yellow, green, blue, and violet. When light interacts with a material, different processes can occur, reflection of light, transmission, scattering, absorption or fluorescence. Various types of radiation differ in wavelength or frequency but are physically identical. Different types of radiation can be used to study local structural environments of atoms in crystals, and therewith chemical and physical material properties.Ģ) elementary particles (e.g., electrons, neutrons, protons) Spectroscopy studies the interaction of radiated energy and matter. By Sylvia-Monique Thomas, University of Nevada Las Vegas Outline Introduction
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