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Tami Spector on "The Molecular Elusive"

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Tami Spector (USF) on "The Molecular Elusive" at a Berkeley LASER http://www.scaruffi.com/leonardo/feb2015b.html

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Tami Spector on "The Molecular Elusive"

  1. 1. The$Molecular$Elusive$ Time$and$Aesthe5cs$in$Chemistry$ $ $ $ $ $ Tami$I.$Spector$ University$of$San$Francisco,$Dept.$of$Chemistry$ (spector@usfca.edu)$
  2. 2. “The%huge%variety%of%chemical%species,%types%of% reac6ons,%and%the%accompanying%poten6al%energy% surfaces%involved%means%that%the%6mescale%over%which% chemical%reac6ons%occur%covers%many%orders%of% magnitude”%(Claire%Vallance,%“Reac6on%Kine6cs”)%$
  3. 3. Very$Slow$Reac5ons$$
  4. 4. Cai$Guo$Qiang,!Restrained!Violence:!Rainbow:!Project!for!Extraterrestrials!No.! 25,%2002%Johannesburg%Biennial,%Johannesburg,%South%Africa%% Gunpowder:%5%kg,%fuse:%500%meters,%Photo:%Kochi%Watari%$$ % Extremely$Fast$Reac5ons$
  5. 5. Reac5ons$That$Occur$on$a$Percep5ble$Time$Scale$ BriggsNRauscher%“Oscilla6ng%Clock%Reac6on”%
  6. 6. •  Reac6ons%materially%appear%to%go%from%star6ng%material%to% product% •  Along%the%path%from%star6ng%material%to%product%various% transient%(very%short%lived)%molecular%species%are%formed% % Oxida6on%of%Iron%to%Fe%(II)% Oxida6on%of%Fe%(II)%%to%Fe%(III)%in%presence%of%water% Fe%III%combine%with%Oxygen%to%form%Fe%(III)%oxide% Fe%(III)%oxide)%is%hydrated%with%water%
  7. 7. •  Dis5nc5on$between$slow$and$fast$reac5ons$is$based$on$how$oNen$ the$reac5ons$occur$on$a$molecular$level,$not$how$quickly$$ •  Given$enough$energy,$all$reac5ons$on$the$molecular$level$proceed$ very$quickly$through$transient$molecular$species$ •  Time$in$Transi5on$State:$femtosecond$(fs)$5me$scale$(10T15$sec)$ •  Time$as$Intermediate$(Minima):$(10T10$T$10T6$sec)$$
  8. 8. Stable$(low$energy)$/Persistent$(long$life5me)$$
  9. 9. “The$transi5on$state$is$neither$one$thing,$ namely,$chemical$reagents,$nor$the$other,$ reac5on$products.$Instead$it$illustrates$the$ mys5cal$event$of$transTsubstan5a5on.”$ %% (John%C.%%Polanyi%and%Ahmed%H.%Zewail,%“Direct%Observa6on%of%the%Transi6on% State,”%1995)% % The$Transi5on$State$(fs$5mescale)*$$ *One%femtosecond%is%10N15%seconds,%that%is,%0.000000000000001%seconds,%which%is%to%a% second%as%a%second%is%to%32%million%years.%%
  10. 10. “Cyclobutadiene,%(CH)4,%is%the%Mona%Lisa%of%organic%chemistry%in% its%ability%to%elicit%wonder,%s6mulate%the%imagina6on,%and% challenge%interpre6ve%ins6ncts.%No%other%organic%compound% combines%such$a$flee5ng$existence$and%so%many%different% syntheses,%with%such%a%propensity%for%different%chemical% reac6ons,%and%with%the%variety%of%calcula6ons%of%its%structure.”%% (Donald%J.%Cram,%et!al.!“The%Taming%of%Cyclobutadiene”,%1991)% % % The$Intermediate$(10T10$T$10T6$sec$5mescale)$$ $ Fe CO CO OC Ce(IV) E
  11. 11. $ Femtochemistry%has%fundamentally%changed%our%view%of% chemical%reac6ons.%From%a%phenomenon%described%in% rela6vely%vague%metaphors%such%as%'ac6va6on'%and% 'transi6on%state',%we%can%now%see%the%movements%of% individual%atoms%as%we%imagine%them.%They%are%no% longer%invisible.% % % % % % % % Press%release%for$Ahmed%Zewail,%awarded%the%1999%Nobel%Prize%in%Chemistry%“For!his! studies!of!the!transi?on!states!of!chemical!reac?ons!using!femtosecond!spectroscopy”$
  12. 12. ...it%is%the%molecules,%and%only%the%molecules,%for%which% claims%of%beauty%and%ar6s6c%crea6vity%are%jus6fied,%no% mader%what%sensual%quali6es%the%corresponding% materials%have. % %(Joachim%Schummer,%“Aesthe6cs%of%Chemical%Products,”%2003)%
  13. 13. The$Transi5on$State$$$
  14. 14. The$Transi5on$State$$$ Time%Snapshot%
  15. 15. The$Transi5on$State$$$ Time%Snapshot% Twisted%TS% PE%Surface%
  16. 16. Time%Snapshot% Twisted%TS% PE%Surface% “Transi6on%state%theory%allows%the%chemist%in%a%sense%to%visualize%?me!itself…6me% that%is%completely%tethered%to%space”%(Stephen%Weininger,%2000)% % Aesthe5cs$of$Transient$Molecular$Systems$ %
  17. 17. “To%be%concentrated%is%to%be%symbolically%powerful”(Barbara%Maria%Stafford,%Echo! Objects,%2007)% Sta5c$Structures$of$Transi5on$States$and$Intermediates$ Compress$5me,$space$and$energy$into$a$single$structure$ Aesthe5cs$of$Transient$Molecular$Systems$ %
  18. 18. %.30!Bullet!Piercing!an!Apple%(Harold%Edgerton,%1964)% “…we%may%also%think%of%sta5c$pictures$which%only%implicitly$have$a$narra5ve$ func5on.%That%is,%where%a%frozen%scene%in%a%tacit%ac6on%sequence%has%been% chosen,%from%which%what%has%preceded%and%will%follow%has%to%be%inferred%by% the%beholder.”%(Michael%Ranta,%“Narra6vity%and%Time%in%Sta6c%Pictures”,%2001)%% %
  19. 19. “In%the%experience%of%any%change%we%may%iden6fy%a% par6cularly%salient%point,%such%as%the%moment%a%longN distance%runner%crosses%the%finishing%line.%We%might% represent%this%as%a%6meNslice%of%the%ac6on,%but%in%fact%(since% we%perceived%it)%it%has%a%nonNzero%dura6on.%This,%then,%is% what%sta6c%images%are%capable%of%depic6ng:%specious! instants!which%are%parts%of%a%larger%movement%represented% by%the%image.%Images%can%thus%represent%a%movement%by% depic6ng%perceptually%minimum%parts%of%it.”%(“Time%and%the% Sta6c%Image,”%Robin%Le%Poidevin,%1997)%% % Instants$have$no$dura5on$and$therefore$are$impercep5ble$ Specious$instant$=$the$smallest$perceivable$part$of$an$instant$ Timeframes$of$Transi5on$States$and$Intermediates$=$specious$instants$ Depic5ons$of$Transi5on$States$and$Intermediates$express$the$ impercep5bility$of$5me$ %
  20. 20. Fin

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