Femtochemistry is the area of physical chemistry that studies chemical reactions on extremely short timescales (approximately 10−15 seconds or one femtosecond, hence the name) in order to study the very act of atoms within molecules (reactants) rearranging themselves to form new molecules (products). In a 1988 issue of the journal Science, Ahmed Hassan Zewail published an article using this term for the first time, stating "Real-time femtochemistry, that is, chemistry on the femtosecond timescale...".[1] Later in 1999, Zewail received the Nobel Prize in Chemistry for his pioneering work in this field showing that it is possible to see how atoms in a molecule move during a chemical reaction with flashes of laser light.[2]
Pump-probe techniques
Application of femtochemistry in biological studies has also helped to elucidate the conformational dynamics of stem-loop RNA structures.[3][4]
Many publications have discussed the possibility of controlling chemical reactions by this method,[clarification needed] but this remains controversial.[5] The steps in some reactions occur in the femtosecond timescale and sometimes in attosecond timescales,[6] and will sometimes form intermediate products. These reaction intermediates cannot always be deduced from observing the start and end products.
The simplest approach and still one of the most common techniques is known as pump–probe spectroscopy. In this method, two or more optical pulses with variable time delay between them are used to investigate the processes happening during a chemical reaction. The first pulse (pump) initiates the reaction, by breaking a bond or exciting one of the reactants. The second pulse (probe) is then used to interrogate the progress of the reaction a certain period of time after initiation. As the reaction progresses, the response of the reacting system to the probe pulse will change. By continually scanning the time delay between pump and probe pulses and observing the response, workers can reconstruct the progress of the reaction as a function of time.
Examplesedit
Bromine dissociationedit
Femtochemistry has been used to show the time-resolved electronic stages of bromine dissociation.[7] When dissociated by a 400 nm laser pulse, electrons completely localize onto individual atoms after 140 fs, with Br atoms separated by 6.0 Å after 160 fs.
^Zewail, A. H. (1988-12-23). "Laser Femtochemistry". Science. 242 (4886): 1645–1653. Bibcode:1988Sci...242.1645Z. doi:10.1126/science.242.4886.1645. ISSN 0036-8075. PMID 17730575. S2CID 220103588.
^The 1999 Nobel Prize in Chemistry, article on nobelprize.org
^Kadakkuzha, B. M.; Zhao, L.; Xia, T. (2009). "Conformational Distribution and Ultrafast Base Dynamics of Leadzyme". Biochemistry. 48 (22): 3807–3809. doi:10.1021/bi900256q. PMID 19301929.
^Lu, Jia; Kadakkuzha, Beena M.; Zhao, Liang; et al. (2011). "Dynamic Ensemble View of the Conformational Landscape of HIV-1 TAR RNA and Allosteric Recognition". Biochemistry. 50 (22): 5042–5057. doi:10.1021/bi200495d. PMID 21553929.
^"Femtochemistry: Past, present, and future". A. H. Zewail, Pure Appl. Chem., Vol. 72, No. 12, pp. 2219–2231, 2000.
^Kling, Matthias F.; Vrakking, Marc J. J. (1 May 2008). "Attosecond Electron Dynamics". Annual Review of Physical Chemistry. 59 (1): 463–492. Bibcode:2008ARPC...59..463K. doi:10.1146/annurev.physchem.59.032607.093532. PMID 18031218.
^Li, Wen; et al. (November 23, 2010). "Visualizing electron rearrangement in space and timeduring the transition from a molecule to atoms". PNAS. 107 (47): 20219–20222. Bibcode:2010PNAS..10720219L. doi:10.1073/pnas.1014723107. PMC2996685. PMID 21059945.
Femtochemistry: Ultrafast Dynamics of the Chemical Bond, Ahmed H Zewail, World Scientific, 1994
External linksedit
Controlling and probing atoms and molecules with ultrafast laser pulses, PhD Thesis
January 01, 1970
femtochemistry, area, physical, chemistry, that, studies, chemical, reactions, extremely, short, timescales, approximately, seconds, femtosecond, hence, name, order, study, very, atoms, within, molecules, reactants, rearranging, themselves, form, molecules, pr. Femtochemistry is the area of physical chemistry that studies chemical reactions on extremely short timescales approximately 10 15 seconds or one femtosecond hence the name in order to study the very act of atoms within molecules reactants rearranging themselves to form new molecules products In a 1988 issue of the journal Science Ahmed Hassan Zewail published an article using this term for the first time stating Real time femtochemistry that is chemistry on the femtosecond timescale 1 Later in 1999 Zewail received the Nobel Prize in Chemistry for his pioneering work in this field showing that it is possible to see how atoms in a molecule move during a chemical reaction with flashes of laser light 2 source source source source source source source source Pump probe techniques Application of femtochemistry in biological studies has also helped to elucidate the conformational dynamics of stem loop RNA structures 3 4 Many publications have discussed the possibility of controlling chemical reactions by this method clarification needed but this remains controversial 5 The steps in some reactions occur in the femtosecond timescale and sometimes in attosecond timescales 6 and will sometimes form intermediate products These reaction intermediates cannot always be deduced from observing the start and end products Contents 1 Pump probe spectroscopy 2 Examples 2 1 Bromine dissociation 3 See also 4 References 5 Further reading 6 External linksPump probe spectroscopy editThe simplest approach and still one of the most common techniques is known as pump probe spectroscopy In this method two or more optical pulses with variable time delay between them are used to investigate the processes happening during a chemical reaction The first pulse pump initiates the reaction by breaking a bond or exciting one of the reactants The second pulse probe is then used to interrogate the progress of the reaction a certain period of time after initiation As the reaction progresses the response of the reacting system to the probe pulse will change By continually scanning the time delay between pump and probe pulses and observing the response workers can reconstruct the progress of the reaction as a function of time Examples editBromine dissociation edit Femtochemistry has been used to show the time resolved electronic stages of bromine dissociation 7 When dissociated by a 400 nm laser pulse electrons completely localize onto individual atoms after 140 fs with Br atoms separated by 6 0 A after 160 fs See also editAttosecond physics 1 attosecond 10 18 s Femtotechnology Ultrafast laser spectroscopy Ultrashort pulse Flash photolysisReferences edit Zewail A H 1988 12 23 Laser Femtochemistry Science 242 4886 1645 1653 Bibcode 1988Sci 242 1645Z doi 10 1126 science 242 4886 1645 ISSN 0036 8075 PMID 17730575 S2CID 220103588 The 1999 Nobel Prize in Chemistry article on nobelprize org Kadakkuzha B M Zhao L Xia T 2009 Conformational Distribution and Ultrafast Base Dynamics of Leadzyme Biochemistry 48 22 3807 3809 doi 10 1021 bi900256q PMID 19301929 Lu Jia Kadakkuzha Beena M Zhao Liang et al 2011 Dynamic Ensemble View of the Conformational Landscape of HIV 1 TAR RNA and Allosteric Recognition Biochemistry 50 22 5042 5057 doi 10 1021 bi200495d PMID 21553929 Femtochemistry Past present and future A H Zewail Pure Appl Chem Vol 72 No 12 pp 2219 2231 2000 Kling Matthias F Vrakking Marc J J 1 May 2008 Attosecond Electron Dynamics Annual Review of Physical Chemistry 59 1 463 492 Bibcode 2008ARPC 59 463K doi 10 1146 annurev physchem 59 032607 093532 PMID 18031218 Li Wen et al November 23 2010 Visualizing electron rearrangement in space and timeduring the transition from a molecule to atoms PNAS 107 47 20219 20222 Bibcode 2010PNAS 10720219L doi 10 1073 pnas 1014723107 PMC 2996685 PMID 21059945 Further reading editAndrew M Weiner 2009 Ultrafast Optics Wiley ISBN 978 0 471 41539 8 Femtochemistry Ultrafast Dynamics of the Chemical Bond Ahmed H Zewail World Scientific 1994External links editControlling and probing atoms and molecules with ultrafast laser pulses PhD Thesis Retrieved from https en wikipedia org w index php title Femtochemistry amp oldid 1211818183 Pump probe spectroscopy, wikipedia, wiki, book, books, library,
