Knowra Ultraviolet–visible spectroscopy Ultraviolet–visible spectroscopy Ultraviolet–visible spectroscopy measures how much ultraviolet and visible light a substance absorbs or transmits across wavelengths. Its spectra reveal electronic transitions and can identify or quantify absorbing species.
Beer–Lambert law : A relation connecting absorbance to concentration, path length, and molar absorptivity for an absorbing substance. It makes absorbance a quantitative measure of concentration under suitable conditions.
Colorimetry : The measurement of color or light absorption, often using selected visible wavelengths to estimate concentration. It is a simpler, often narrower-wavelength approach to measurements that UV–visible instruments can also perform.
Electromagnetic spectrum : The full range of electromagnetic radiation, ordered by frequency or wavelength. Ultraviolet and visible light occupy adjacent regions within this broader spectrum.
Infrared spectroscopy : A technique that studies molecular vibrational transitions by measuring infrared radiation absorbed by a sample. It probes vibrational rather than primarily electronic transitions and generally uses longer wavelengths.
Electronic transition : A change in an electron’s energy state caused by absorption or emission of electromagnetic radiation. Absorbed ultraviolet and visible photons promote electrons between molecular or atomic energy levels.
DNA quantification : The estimation of DNA concentration, commonly from ultraviolet absorbance near 260 nanometers. Nucleic acids absorb ultraviolet light, allowing rapid concentration estimates from a spectrum.
Wavelength : The distance between successive corresponding points of a wave, such as adjacent peaks. Spectra assign absorption measurements to wavelengths, usually reported in nanometers.
Fluorescence spectroscopy : A technique that measures light emitted by a substance after it absorbs excitation light. It detects emitted light, whereas absorption spectroscopy measures the loss of transmitted light.
Chromophore : An atom or group of atoms responsible for a molecule’s characteristic absorption of light. Chromophores determine which wavelengths a molecule absorbs and shape its spectrum.
Protein quantification : The measurement of protein concentration using absorbance or color-forming chemical assays. Direct ultraviolet absorbance and visible colorimetric assays are common spectrophotometric methods.
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