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The emission spectrum of a chemical element or chemical compound is the spectrum of frequencies of electromagnetic radiation emitted due to electrons making a transition from a high energy state to a lower energy state.
The infrared absorption spectrum of NASA laboratory sulfur dioxide ice is compared with the infrared absorption spectra of ices on Jupiter's moon, Io credit NASA, Bernard Schmitt, and UKIRT. Absorption spectroscopy is useful in chemical analysis [5] because of its specificity and its quantitative nature. The specificity of absorption spectra ...
The plot for vapor is a transformation of data Synthetic spectrum for gas mixture ' Pure H 2 O ' (296K, 1 atm) retrieved from Hitran on the Web Information System. [6] Liquid water absorption spectrum across a wide wavelength range [missing source] The absorption of electromagnetic radiation by water depends on the state of the water.
Jablonski diagram including vibrational levels for absorbance, non-radiative decay, and fluorescence. When a molecule absorbs a photon, the photon energy is converted and increases the molecule's internal energy level. Likewise, when an excited molecule releases energy, it can do so in the form of a photon.
The classical example of a discrete spectrum (for which the term was first used) is the characteristic set of discrete spectral lines seen in the emission spectrum and absorption spectrum of isolated atoms of a chemical element, which only absorb and emit light at particular wavelengths. The technique of spectroscopy is based on this phenomenon.
Nevertheless, the absorbance unit or AU is commonly used in ultraviolet–visible spectroscopy and its high-performance liquid chromatography applications, often in derived units such as the milli-absorbance unit (mAU) or milli-absorbance unit-minutes (mAU×min), a unit of absorbance integrated over time.
Emission spectrum of a fluorescent light, exhibiting many spectral lines. Each line corresponds to an energy level in one of the elements inside the light. A spectral line can result from an electron transition in an atom, molecule or ion, which is associated with a specific amount of energy, E. When this energy is measured by means of some ...
Stokes fluorescence is the emission of a longer-wavelength photon (lower frequency or energy) by a molecule that has absorbed a photon of shorter wavelength (higher frequency or energy). [6] [7] [8] Both absorption and radiation (emission) of energy are distinctive for a particular molecular structure. If a material has a direct bandgap in the ...