Flash photolysis is a pump-probe laboratory technique, in which a sample is first excited by a strong pulse of light from a

pulsed laser Pulsed operation of lasers refers to any laser not classified as continuous wave, so that the optical power appears in pulses of some duration at some repetition rate. Silfvast, William T. (1996). ''Laser Fundamentals'', Cambridge University Press. ...

nanosecond A nanosecond (ns) is a unit of time in the International System of Units (SI) equal to one billionth of a second, that is, of a second, or 10 seconds. The term combines the SI prefix ''nano-'' indicating a 1 billionth submultiple of an SI unit ( ...

, picosecond, or femtosecond pulse width or by another short-pulse light source such as a flash lamp. This first strong pulse is called the pump pulse and starts a

chemical reaction A chemical reaction is a process that leads to the IUPAC nomenclature for organic transformations, chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the pos ...

or leads to an increased population for energy levels other than the ground state within a sample of atoms or molecules. Typically the absorption of light by the sample is recorded within short time intervals (by a so-called test or probe pulses) to monitor relaxation or reaction processes initiated by the pump pulse. Flash photolysis was developed shortly after

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

as an outgrowth of attempts by military scientists to build cameras fast enough to photograph missiles in flight. The technique was developed in 1949 by

Manfred Eigen Manfred Eigen (; 9 May 1927 – 6 February 2019) was a German biophysical chemist who won the 1967 Nobel Prize in Chemistry for work on measuring fast chemical reactions. Eigen's research helped solve major problems in physical chemistry and ...

Ronald George Wreyford Norrish Ronald George Wreyford Norrish FRS (9 November 1897 – 7 June 1978) was a British chemist who was awarded the Nobel Prize in Chemistry in 1967. Education and early life Norrish was born in Cambridge and was educated at The Perse School and Emm ...

and

George Porter George Porter, Baron Porter of Luddenham (6 December 1920 – 31 August 2002) was a British chemist. He was awarded the Nobel Prize in Chemistry in 1967. Education and early life Porter was born in Stainforth, near Thorne, in the then West ...

, who won the 1967

Nobel Prize in Chemistry ) , image = Nobel Prize.png , alt = A golden medallion with an embossed image of a bearded man facing left in profile. To the left of the man is the text "ALFR•" then "NOBEL", and on the right, the text (smaller) "NAT•" then "M ...

for this invention. Over the next 40 years the technique became more powerful and sophisticated due to developments in optics and lasers. Interest in this method grew considerably as its practical applications expanded from chemistry to areas such as biology, materials science, and

environmental science Environmental science is an interdisciplinary academic field that integrates physics, biology, and geography (including ecology, chemistry, plant science, zoology, mineralogy, oceanography, limnology, soil science, geology and physical geograp ...

s. Today, flash photolysis facilities are extensively used by researchers to study light-induced processes in

organic molecule In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. Th ...

polymer A polymer (; Greek '' poly-'', "many" + ''-mer'', "part") is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic a ...

nanoparticle A nanoparticle or ultrafine particle is usually defined as a particle of matter that is between 1 and 100 nanometres (nm) in diameter. The term is sometimes used for larger particles, up to 500 nm, or fibers and tubes that are less than 1 ...

semiconductor A semiconductor is a material which has an electrical resistivity and conductivity, electrical conductivity value falling between that of a electrical conductor, conductor, such as copper, and an insulator (electricity), insulator, such as glas ...

photosynthesis Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored i ...

in plants, signaling, and light-induced conformational changes in biological systems.

References

{{Authority control Photochemistry Chemical kinetics Time-resolved spectroscopy

See also

References