Mostafa El-Sayed | |
|---|---|
 El-Sayed in March 2016 | |
| Born | (1933-05-08)8 May 1933 (age 92) |
| Alma mater | Ain Shams University Florida State University |
| Known for | Nanotechnology Spectroscopy El-Sayed rule |
| Awards | King Faisal International Prize 1990 Irving Langmuir Award 2002 National Medal of Science 2007 Glenn T. Seaborg Medal 2009 Priestley Medal 2016 |
| Scientific career | |
| Fields | Chemical physicist |
| Institutions | Georgia Institute of Technology Harvard University University of California at Los Angeles |
| Doctoral advisor | Michael Kasha[1] |
Mostafa A. El-Sayed (Arabic:مصطفى السيد) is anEgyptian-American physical chemist, nanoscience researcher, member of theNational Academy of Sciences andUS National Medal of Science laureate. He is known for the spectroscopy rule named after him, theEl-Sayed rule.[2][3][4]
El-Sayed was born in Zifta, Egypt and spent his early life in Cairo. He earned hisB.Sc. in chemistry fromAin Shams University Faculty of Science,Cairo in 1953.[5] El-Sayed earned his doctoral degree in chemistry fromFlorida State University working withMichael Kasha, the last student of the legendaryG. N. Lewis.[citation needed] While attending graduate school he met and married Janice Jones, his wife of 48 years. He spent time as a post-doctoral researcher atHarvard University,Yale University and theCalifornia Institute of Technology before joining the faculty of theUniversity of California at Los Angeles in 1961. In 1994, he retired from UCLA and accepted the position of Julius Brown Chair and Regents Professor of Chemistry and Biochemistry at theGeorgia Institute of Technology. He led theLaser Dynamics Lab there until his full retirement in 2020.
El-Sayed is a former editor-in-chief of theJournal of Physical Chemistry (1980–2004).[6][7]
El-Sayed's research interests include the use ofsteady-state andultra fast laser spectroscopy to understand relaxation, transport and conversion of energy inmolecules, insolids, inphotosynthetic systems, semiconductorquantum dots and metalnanostructures. The El-Sayed group has also been involved in the development of new techniques such as magnetophotonic selection, picosecondRaman spectroscopy and phosphorescence microwave double resonance spectroscopy. A major focus of his lab is currently on the optical and chemical properties ofnoble metalnanoparticles and their applications in nanocatalysis,nanophotonics andnanomedicine. His lab is known for the development of thegold nanorod technology. As of 2021, El-Sayed has produced over 1200 publications in refereed journals in the areas ofspectroscopy,molecular dynamics andnanoscience, with over 130,000 citations.[8]
For his work in the area of applyinglaser spectroscopic techniques to study of properties and behavior on thenanoscale, El-Sayed was elected to theNational Academy of Sciences in 1980. In 1989 he received theTolman Award, and in 2002, he won theIrving Langmuir Award in Chemical Physics. He has been the recipient of the 1990King Faisal International Prize ("Arabian Nobel Prize") in Sciences,Georgia Tech's highest award, "The Class of 1943 Distinguished Professor", an honorary doctorate of philosophy from theHebrew University, and several other awards including some from the differentAmerican Chemical Society local sections. He was aSherman Fairchild Distinguished Scholar at theCalifornia Institute of Technology and an Alexander von Humboldt Senior U.S. Scientist Awardee. He served as editor-in-chief of theJournal of Physical Chemistry from 1980 to 2004 and has also served as the U.S. editor of theInternational Reviews in Physical Chemistry. He is a Fellow of theAmerican Academy of Arts and Sciences, a member of theAmerican Physical Society, theAmerican Association for the Advancement of Science and theThird World Academy of Science. Mostafa El-Sayed was awarded the 2007 USNational Medal of Science "for his seminal and creative contributions to our understanding of theelectronic andoptical properties ofnanomaterials and to their applications in nanocatalysis andnanomedicine, for hishumanitarian efforts of exchange among countries and for his role in developing the scientific leadership of tomorrow."[9] Mostafa was also announced to be the recipient of the 2009Ahmed Zewail prize in molecular sciences. In 2011, he was listed #17 in Thomson-Reuters listing of the Top Chemists of the Past Decade.[10] Professor El-Sayed also received the 2016Priestley Medal, theAmerican Chemical Society’s highest honor, for his decades-long contributions to chemistry.[11]
The rate of intersystem crossing is relatively large if the radiationless transition involves a change of orbital type.
— Mostafa El-Sayed,[12]
This rule pertains tophosphorescence and similar phenomena. Electrons vibrate and resonate around molecules in differentmodes (electronic state), usually depending on the energy of the system of electrons. This law states that constant-energy flipping between two electronic states happens more readily when the vibrations of the electrons are preserved during the flip: any change in thespin of an electron is compensated by a change in its orbital motion (spin-orbit coupling).
Intersystem crossing (ISC) is a photophysical process involving an isoenergetic radiationless transition between twoelectronic states having different multiplicities. It often results in a vibrationally excited molecular entity in the lower electronic state, which then usually decays to its lowestmolecular vibrational level. ISC is forbidden by rules of conservation ofangular momentum. As a consequence, ISC generally occurs on very long time scales. However, the El-Sayed rule states that the rate of intersystem crossing, e.g. from the lowestsinglet state to the triplet manifold, is relatively large if the radiationless transition involves a change ofmolecular orbital type.[13][14] For example, a (π,π*) singlet could transition to a (n,π*)triplet state, but not to a (π,π*) triplet state and vice versa. Formulated by El-Sayed in the 1960s, this rule found in mostphotochemistry textbooks as well as theIUPACGold Book.[15] The rule is useful in understandingphosphorescence, vibrational relaxation,intersystem crossing,internal conversion and lifetimes of excited states in molecules.
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