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Electron Driven Reactions in Free and Bound Molecules Eugen Illenberger and coworkers Institut fuer Chemie und Biochemie Physikalische und Theoretische.

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Presentation on theme: "Electron Driven Reactions in Free and Bound Molecules Eugen Illenberger and coworkers Institut fuer Chemie und Biochemie Physikalische und Theoretische."— Presentation transcript:

1 Electron Driven Reactions in Free and Bound Molecules Eugen Illenberger and coworkers Institut fuer Chemie und Biochemie Physikalische und Theoretische Chemie

2 Electron driven reactions in molecules Ionisation Electronic Excitation e - / hv Free Coupled to something Electron capture

3 Sub-excitation: below the threshold of electronic excitation Photon (electromagnetic wave) Electron (m<

4 Dissociation Autodetachment Resonant Capture Dissociative Electron Attachment (DEA )

5 e - ( eV) M-M- X-X- R M-M- e-e- e-e- Isolated molecules (effusive molecular beam) Molecular clusters (supersonic molecular beam) Adsorbed and condensed molecules (UHV) 20 K

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7 Electron Driven Processes Subexcitation Energies Single molecules (effusive beam) Molecular aggregates (supersonic beam expansion) Molecular nanofilm (UHV) Biomolecular systems

8 Electron Monochromator Molecular Beam Quadrupole Faraday Cup Skimmer Detector Nozzle Computer Stagnation Chamber Laser (IR, UV) e - + M  M -#  R + X -

9 F - + SF 4 NCO F + SF 4 NCO - (10 3 ) (2.5x10 3 ) (1) NCO - + SF 5 NCO + SF 5 - Tania Oster, EI Int. J. Mass Spectrom. 85 (1988) 125 e - + SF 5 NCO  SF 5 NCO -#

10 Judith Langer et al. Phys. Chem. Chem. Phys. 4 (2002) 5105 F 3 C-CF 2 I selective C-I bond cleavage at 0 eV  ≈ cm 2 Direct electronic dissociation along a repulsive surface

11 E* = Total Excess Energy TOF analysis of I -

12 CF 3 I - C2F5I-C2F5I- LUMO:  *(C-I)

13  CF 3 -CF 2 -I E trans : 66% E vib : 19% E rot : 15% Judith Langer, Stefan Matejcik, EI PCCP 4 (2002) 5105

14 (CF 3 ) 2 C=N-N=C(CF 3 ) 2 ) HFFA

15 Excision of CN - : Multiple bond cleavages and rearrangement Ilko Bald, Iwona Dabkowska, Oddur Ingólfsson & EI JCP (2007) 2983

16 Energy conservation: CH 3 CH 3 + O - Mario Orzol, Isabel Martin, Judith Langer Jaroslav Kocisek, Iwona Dabkowska & EI (2007)

17 Some Applications

18 STM M e-e- Single Molecule Engineering Selective bond cleavage K.-H. Rieder et al. R. Palmer et al. Selective vibrational excitation J. I. Pascual et al.

19 Scientists from the 's Nanoscale Science Facility have made a breakthrough in manipulating the smallest single molecules and atoms by devising a new technique of molecular dissection which induces the "birth" of a daughter atom from the parent molecule. This breakthrough, which is highlighted in a paper published in the journal, Nature, today (Thursday 17 March). The new method, devised by Professor Richard Palmer and Dr Peter Sloan, uses the tip of a Scanning Tunnelling Microscope (STM) to inject two electrons into the parent chlorobenzine molecule to induce a dissociation event - the first electron sets the molecule into vibration and the second electron breaks the bond between the parent molecule and daughter chlorine atom.

20 e-e- M X-X- h Substrate Induced Photochemistry h Photoabsorption  Fragment ion desorption (John Polanyi et al.) Desorption of neutral molecules (Martin Wolf, Gerhard Ertl. et al.

21 V(z) Distance Molecule-Surface (z) M-M- M Desorption of Neutrals via Resonances P. Antoniewicz, Phys. Rev. B21(1980) 388 G. Ertl, M. Wolf et al.

22 Molecular Aggregates

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24 Dissociation (DEA) Collisional stabilization Van der Waals clusters Electron induced intra- cluster chemistry new anionic products e - + relaxation

25 Dissociative  Associative Attachment Petra Tegeder, Oddur Ingólfsson et al., Z. Phys. Chem. 195 (1996) 217. C 6 F 5 X X=Cl, Br, I

26 Reaction Coordinate Q QcQc C6F5XC6F5X

27 Intracluster Ion-Molecule Reactions X - + RY  [XRY] #-  XR + Y - Nucleophilic Displacement (S N 2) Reaction e.g. : F - + CH 3 Cl  CH 3 F + Cl - (Judith Langer)

28 Binary Clusters (NF 3 ) n (CH 3 Cl) m

29 Single CH 3 Cl e-e- No Ions via DEA Resonant scattering Cl - S N 2 Reaction F-F- Binary Clusters (NF 3 ) n (CH 3 Cl) m F -

30 e - + CH 3 Cl  CH 3 + Cl -  < cm 2 (unmeasurably small) from impurity

31 Judith Langer, Stefan Matejcik & EI Phys. Chem. Chem. Phys. 2 (2000) 1001 DEA to NF 3 S N 2 Reaction

32 Electron attachment to CH 3 COCH 3 (A) Single molecules [CH 3 COCH 2 ] ¯ = [M ¯ H] ¯ Electron energy / eV Ion yield / s -1 HC

33 Clusters Mass / amu p = 0.25 bar, ε = 0 eV, M: Ar 1:50 with M = CH 3 COCH 3 CH 3 COCH 3 (58 amu) Judith Langer, Isabel Martin & EI (2007) Mass spectrum New dissociative channel at ≈ 0 eV: Loss of 2 molecules H 2 a)from acetone dimer anion (112 amu) b)from dimer or trimer anions forming ion- molecules-complexes ( amu) no M ¯ Ion intensity / arbitrary units

34 Condensed Phase Reactions Electron stimulated desorption via DEA (the effect of the medium) Slow Electrons as a Soft Tool for Surface Modifications Substrate Mediated Processes

35 Fritz Weik and EI, J. Chem. Phys. 103 (1995) 1406 ** No fragment ion desorption via DEA F 2 C=CF 2

36 CF 3 I Gas Condensed Phase CPL 296 (1998) 208 Surf. Sci. 528 (2003) 67 6 ML Strong enhancement

37 CF 3 - M M* M* - E M M* M* - 0 Free molecule Bound molecule (E T = 1.5 eV)

38 Biomolecular Systems

39 Radiation Damage Electron driven rections

40 EA(T-H) ≈ eV H. A-Carime, S. Gohlke, EI PRL 92 (2004) Thymine: e - +T  T -#  (T-H) - + H DNA Bases

41 Thymine PRL 92 (2004) eV 1.8 eV

42 Cross section (Å 2 ) Electron energy (eV) ** 1 3 DB state

43

44 Deoxyribose in DNA TAR Ribose Tetrahydrofuran (THF) as model for the sugar unit in DNA ?

45  * Resonance Ilko Bald, Janina Kopyra, Iwona Dabkowska Egill Antonsson & EI, JCP 126 (2007)

46 Electron attachment to the phosphate group

47 DEA to dibutyl phosphate (DBP) Constanze König, Janina Kopyra, Ilko Bald & EI Phys. Rev. Letters 97 (2006) Strand break by single bond cleavage EIPAM fellow

48 DEA to dibutyl phosphate (DBP) EA(PO 3 ) = 4.95 eV EA(PO 2 ) = 3.42 eV Constanze König, Janina Kopyra, IlkoBald & EI Phys. Rev. Letters 97 (2006) SSB via excision of P-containing units

49 R. Barrios, P Skurski and J. Simons, JPC B 106 (2002) 7991 Simons et al. JACS 126 (2004) 6441.

50 No transfer of excess charge initially localised on T H. A.Carime et al., Chem. Phys. Letters 387 (2004) 267. S. Ptasinska et al., Angew. Chem. Int. Ed. 45 (2006) eV

51 T-A Pairing 1 eV 1.8 eV

52 HCOOHformic acid Cluster Experiments (Supersonic beam) CF 3 COOH / CF 3 COOD

53 + H + HF + FCOOH Isabel Martin et al., CPL 419 (2005) 228 CF 3 COOH single molecules Bratislava/Berlin

54 CF 3 COOH clusters in the molecular beam Judith Langer et al., Int. J. Mass Spectrom 249/250 (2006) 477

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56 strong enhancement of electron capture cross section chemical reactions induced at very low energy

57 NBs act as antennas for low energy electrons eventually transfer to the backbone (SSB) Sugar unit is sensitive Phosphate group is sensitive  Different mechanisms contribute to SSBs

58 Future Directions: Model DA immobilised on microarrays Transfer of larger units into the gas phase

59 Hybridization Tihomir Solomun et al. Eur. J. Physics D 35 (2005) 437.

60 Laser induced acoustic desorption (LIAD) (Ilko Bald)  m foil Pulsed laser (Nd Yag) Desorbing neutrals Electrons

61 Paul Scheier, Tilmann Märk, Universität Innsbruck Roger Azria, Anne Lafossse, Robert Abouaf, Université Paris Sud, Orsay Nigel Mason, UCL London/ Open U. Milton Keynes Stefan Matejcik, Michal Stano, Jan D. Skalny, Comenius University, Bratislava Michael Huels, Léon Sanche, Université de Sherbrooke, Québec Hartmut Hotop, Kaiserslautern /Chris Mayhew, Birmingham E. Krishnakumar, S.V. K. Kumar, Tata Institute, Bombay Gregorsz Karwasz, Torun/Trento Franco Gianturco, Rome Oddur Ingólfsson, Reykjavik Sascha GohlkeJanina Kopyra Richard Balog Andrzej Rosa Judith Langer Iwona Dabkowska Esther FischbachConstanze König Ilko BaldTomas Skalicky Isabel MartinMichal Stano Hassan Abdoul-CarimeTihomir Solomun Werner F. SchmidtJessica Scheike Mario OrzolMarie Perot FU Berlin

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64 Deutsche Forschungsgemeinschaft (DFG) European Union, ESF (EPIC, COST, EIPAM) Volkswagen Stiftung Bundesministerium für Wirtschaft und Arbeit (BMWA) INNOVENT Jena Alexander-von-Humboldt-Stiftung Deutscher Akademischer Austausch Dienst (DAAD) Freie Universität Berlin NATO Research Council


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