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[9] [10] Researchers in optical physics use and develop light sources that span the electromagnetic spectrum from microwaves to X-rays. The field includes the generation and detection of light, linear and nonlinear optical processes, and spectroscopy. Lasers and laser spectroscopy have transformed optical science.
Photochemical immersion well reactor (50 mL) with a mercury-vapor lamp.. Photochemistry is the branch of chemistry concerned with the chemical effects of light. Generally, this term is used to describe a chemical reaction caused by absorption of ultraviolet (wavelength from 100 to 400 nm), visible (400–750 nm), or infrared radiation (750–2500 nm).
Various sources define visible light as narrowly as 420–680 nm [7] [8] to as broadly as 380–800 nm. [9] [10] Under ideal laboratory conditions, people can see infrared up to at least 1,050 nm; [11] children and young adults may perceive ultraviolet wavelengths down to about 310–313 nm. [12] [13] [14]
Photodissociation, photolysis, photodecomposition, or photofragmentation is a chemical reaction in which molecules of a chemical compound are broken down by absorption of light or photons. It is defined as the interaction of one or more photons with one target molecule that dissociates into two fragments.
Quantum chemistry, a subfield of physical chemistry especially concerned with the application of quantum mechanics to chemical problems, provides tools to determine how strong and what shape bonds are, [2] how nuclei move, and how light can be absorbed or emitted by a chemical compound. [3]
However, the intensity of light drops rapidly with the distance to the light source due to adsorption by the reactants. [12] The influence of the radiation on the reaction rate can often be represented by a power law based on the quantum flow density, i.e. the mole light quantum (previously measured in the unit einstein) per area and time. One ...
The incoming light excites a polarization that can be described with the semiconductor Bloch equations. [8] [9] Once the photons are absorbed, electrons and holes are formed with finite momenta in the conduction and valence bands, respectively. The excitations then undergo energy and momentum relaxation towards the band-gap minimum.
The rotation of light is measured using a polarimeter and is expressed as the optical rotation. Enantiomers can be separated by chiral resolution . This often involves forming crystals of a salt composed of one of the enantiomers and an acid or base from the so-called chiral pool of naturally occurring chiral compounds, such as malic acid or ...