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Electron induced chemistry – applications from Astrochemistry to cancer therapy Nigel John Mason.

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Presentation on theme: "Electron induced chemistry – applications from Astrochemistry to cancer therapy Nigel John Mason."— Presentation transcript:

1 Electron induced chemistry – applications from Astrochemistry to cancer therapy Nigel John Mason

2 Electron Induced Processes Atmospheric physics and planetary atmospheres

3 Electron Induced Processes Astrochemistry: Formation of molecules in Space

4 Electron Induced Processes Semiconductor plasmas

5 Electron Induced Processes Lighting industry

6 Electron Induced Processes Radiation damage of DNA and cellular material

7 Electron Induced Processing Nanotechnology and surface engineering

8 Electron Induced Chemistry; In this presentation I will describe; The role of low energy electrons in electron driven chemistry Show how such research can be applied to study fundamental problems in natural and industrial world

9 In Europe this research has been developed through collaborative programme Funded by EU 2002 Framework V Network EPIC Electron and Positron Induced Chemistry EU COST Action P9 RADAM Radiation damage ESF Programme Electron Induced Processing at the Molecular Level (EIPAM) EU COST Action CM0601 Electron Controlled Chemical Lithography EU COST Action CM0805 Astrochemistry Electron Based research in Europe

10 How do electrons trigger chemistry ? By Exciting Dissociating or ionising molecules with subsequent products being reactants in collisional chemistry Electron Induced Chemistry; Chemical Control at the Molecular Level

11 Consider for example simple electron induced dissociation through an excited molecular electronic state. e- + M  M#  X + R + e(1) R + AB  AR + B (2) Example 1 Formation of glycine in the Interstellar medium Electron Induced Chemistry; Chemical Control at the Molecular Level

12 Example: Glycine in the ISM ? Kuan et al 2003 –The Astrophysical Journal, 593:848–867, 2003 Searched for interstellar conformer I glycine (NH 2 CH 2 COOH), the simplest amino acid, in the hot molecular cores Sgr B2(N-LMH), Orion KL ALMA will search/dectect for Glycine Kleinman-Low (KL) Region of the Orion Nebula Subaru Telescope, NAOJ

13  To pumping station Continuous flow cryostat Ion gauge Cryogen inlet via transfer line Temperature controller Sources E-gun Synchrotron Ion Source Resistive heater Thermocouples MgF 2 /ZnSe substrate Copper sample mount Detectors - UV-VIS / FTIR detector - Photomultiplier Tube Sources -UV-VIS / FTIR spectrometer -Synchrotron Vacuum chamber to mimic empty space: –P~ mbar Still > a million times higher than ISM! Temperature very cold in space –Continuous flow LHe/LN2 cryostat 12 K < T < 450 K Material to mimic grains Make ice Samples Use spectroscopy to see what you make

14 Experimental Procedure Ice sample was prepared at 10 K by depositing binary gas mixtures of methylamine (CH 3 NH 2 ; and carbon dioxide (CO 2 ) onto a cooled silver crystal. Ice thickness & column densities determined by Beer- Lambert Law Column densities of carbon dioxide and methylamine of 2.0  0.4  cm -2 and 7.2  0.2  cm -2 respectively

15 5 keV Electron irradiation of methylammine and carbon dioxide ice makes glycine simple amino acid

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17 05 th Jan 2006 Chemistry of Planets Electron Induced Chemistry Some examples of laboratory study of electron induced synthesis of molecules under astrochemical conditions. Chemical synthesis in 1:1 Mixture of NH 3 :CO 2 Ice with 1 keV electrons at 30 K

18 05 th Jan 2006 Chemistry of Planets Formation of ammonium carbamate

19 05 th Jan 2006 Chemistry of Planets Electron Induced Chemistry Some examples of laboratory study of electron induced synthesis of molecules under astrochemical conditions. Chemical synthesis in the Irradiation of 1:1 Mixture of NH 3 :CH 3 OH ice with 1 keV electrons at 20 K

20 05 th Jan 2006 Chemistry of Planets Formation of ethylene glycol in pure methanol ice HOH 2 C-CH 2 OH

21 05 th Jan 2006 Chemistry of Planets Formation of methyl formate CH 3 OHCO

22 05 th Jan 2006 Chemistry of Planets Formation of formamide HCONH 2 (Khanna, Lowenthal et al. 2002)

23 Electron Induced Chemistry; Chemical Control at the Molecular Level These are examples of high energy electrons ‘Blasting’ molecules apart or release of secondary electrons !! But at low energies electrons can do surprising things !

24 Electron Induced Chemistry; Chemical Control at the Molecular Level At low energies electrons can do surprising things ! They can ‘stick’ to the molecule To form a negative ion or ‘resonance’ But only for a very short period of time ( s) Then the electron detaches Leaving molecule excited or not (elastic scattering) But this process can also lead to the dissociation of the molecule This is the process of Dissociative Electron Attachment (DEA)

25 Bond Selectivity using Electrons Process of Dissociative Electron Attachment

26 Electron Induced Chemistry; Chemical Control at the Molecular Level Dissociative electron attachment therefore provides a method for breaking up molecules at low energies Energies lower than the chemical bond energy !!! Hence electrons can initiate chemistry

27 Electron Induced chemistry Electrons used to ‘tune’ the products of a reaction Through selective bond dissociation different energy different pathways Electron Induced Chemistry; Chemical Control at the Molecular Level

28 Selective C-Cl bond cleavage at 0 eV Selective C-F bond cleavage at 3.2 eV Illenberger et al Berlin

29 Nucleophilic Displacement (S N 2) Reaction e.g. : F - + CH 3 Cl  CH 3 F + Cl -

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

31 S N 2 Reaction Illenberger et al Berlin

32 (NF 3 ) n (CH 3 Cl) m CH 3 Cl e-e- e-e- e-e- no ions F-F- Cl -

33 Chemical surface transformations using electron induced reactions/ DEA produces products that subsequently react on the surface E.g. Irradiate film of NF 3 and CH 3 Cl Form CH 3 F

34 e-e- F-F- CH 3 Cl CH 3 F Cl-

35 R. Balog and E. Illenberger Phys. Rev. Letters Complete chemical Transformation of thin films e + C2F4Cl2 → C2F4 + Cl2 C2F4 desorbs So surface transformation to 100% Cl 2 film !! Cl 2

36 Basic e - -molecule interactions Resonances E 0 dependence Control via e - -induced chemistry developing electron lithography e - -induced chemistry Cross sections Typical reactions and products Reaction sequences Surface functionalization Reactions at the interface of materials Modification of materials properties - structural - electrical - permeability - optical

37 Functionalization of H-diamond CH 3 CN / H-diamond at 35 K, E 0 = 2 eV C. Jäggle Cooperation: R.Azria and A.Lafosse e - (E 0 ) CH 3 CN H H H H H H H H H H H H H CH 2 CN H H H NCCH 2

38 DEA and biomolecules DEA is a universal process So DEA will occur in biomolecules including those constituents of DNA So can DEA induced fragmentation lead to DNA damage ?

39 In many molecules DEA leads to H atom loss This is most dominant process in DEA to organic acids E.g. acetic, formic and …

40 Relative cross sections of H  channel for Carboxylic acids Electron energy (eV) Ion current

41 O H C C H H O H O H C C H H O D CH 3 COOD CH 3 COOH Prabhudesai et al. PRL (2005)

42 Is this unique for carboxylic acids? CH 3 OH CH 3 CH 2 OH

43 H  from Amine H  / CH 4 H  / NH 3 CH 3 CH 2 CH 2 NH 2

44  or X e-e- < 20 eV Single and double strand breaks may be induced by secondary species: a large number of secondary electron with kinetic energies below about 20 eV, are produced along the radiation track Damage of the genom in living cell by ionising radiation is about 1/3 a direct and 2/3 an indirect processes. Radiation damage to DNA Can electrons damage DNA?

45 super coiled DNA single strand break SSB double strand break DSB DNA damage - strand breaks

46 Mechanisms for ssb and dsb induction at low-energies Boudaiffa et al. (Leon Sanche, Sherbrooke Canada) demonstrated that there apperas tpo be a corrrelation between patterns of ssb and dsb induced in DNA and DEA of constituent molecules Resonant Formation of DNA Strand Breaks by Low- Energy (3 to 20eV) Electrons. Science 287, (2000). B. Boudaiffa, P. Cloutier, D. Hunting, M.A. Huels et L. Sanche.

47 L. Sanche et al. Science, 287 (2000) 1659 and PRL (2004) Strand breaks of DNA  SSB DSB Electron Energy (eV) DNA breaks per 10 4 incident electrons

48 L. Sanche et al. Science, 287 (2000) 1659 and PRL (2004) Strand breaks of DNA  SSB DSB Electron Energy (eV) DNA breaks per 10 4 incident electrons e - + DNA → DNA - * → fragments

49 DNA – deoxyribonucleoside acid

50 ion beam neutral beam electron beam FWHM ~ 100 meV I e ~ few nA Hemispherical electron monochromator oven quadrupole mass spectrometer channeltron ~ 150°C ~ mbar Experimental setup – gas phase Innsbruck

51 Thymine + e - → TNI - * → electron attachment C5H6N2O2-C5H6N2O2- e-e- dissociative electron attachment (T-H) - + H (T-2H) - + neutral(s) C 4 H 5 N 2 O - + neutral(s) C 2 H 3 N 2 O - + neutral(s) C 3 H 2 NO - + neutral(s) CN - + neutral(s) O - + neutral(s) H - + neutral(s) OCN - + neutral(s) → → → → → → C 3 H 4 N - + neutral(s) → → → → Dissociative Electron Attachment 126 amu 125 amu 124 amu 1 amu 16 amu 26 amu 42 amu 54 amu 68 amu 99 amu 73 amu

52 Cross section ( m 2 ) Electron energy (eV) H loss e-e- Electron Attachment to Thymine (M-H) amu

53 Δ #,1 1.4 binding energies of C-H and N-H bonds electron affinities of various (U-H) isomers E min # eV 5.0 eV 4.5 eV 5.8 eV -4.5 eV -3.4 eV -2.9 eV -2.7 eV C C C C O N O N C C C C C O N O N C e-e- Quantum Chemical Calculations

54 Thymine-methyl-d3-6-d 5-methyluracil 1-methylthymine Uracil3-methyluracil Thymine Carbon Nitrogen Oxygen Hydrogen Deuterium Thymine-methyl-d3-6-d 5-methyluracil 1-methylthymine Uracil 3-methyluracil Isotope and site labelling thymine

55 m1T m3U 1 3 Site and bond selectivity in DEA 129 amu

56 GCAT G+C+A+T EA - electron affinity EA(CN)= 3.82 eV EA(CNO)= 3.61 eV DEA to oligomers O P O-O- NH 2 N N N N HO O O O NH 2 O N N P O O O O-O- O O N N N N N N O O O O O O O-O- O OH G C A T oligomer tetramer (1172 amu) P CN - CNO - Gas phase Condensed phase

57 Does DEA explain effectiveness of some radiosensitizers ? Observation of correlation between carcinogens and DEA rates ? Effectiveness of halogenated compounds as radiosensitizers

58 UracilThymine Bromouracil (Radiosensitizer )

59 (UCl) - (UCl-HCl) - (Cl) - Ratios: X - /(U-yl) - = 1.3, 40, 490 (X=Cl,Br,I) Present: Cl - /(U-yl) - =0.47 Halo-uracils measured by Illenberger et al Berlin. UCl + e -  anions

60 + Br.  ≈ 600 Å 2 Freie University Berlin

61 New techniques for electron scattering! The Method of Scanning Tunnel Microscopy Electron current from fine metal tip interacts with (metal) substrate Electron Induced Chemistry; Nanotechnology

62 spm/stm-operation.gif

63 STM M e-e- Single Molecule Engineering

64 Changing environment like temp., pressure or catalyst Coherent pulse sequence –(Potter et.al. Nature 355, 66 (1998)) Optimal control by shaping of fast pulses –(Levis et.al. Science 292, 709 (2001)) Addressing single molecule using STM –(Pascual et al. Nature 2003, Sloan and Palmer, Nature 2005) Optimal control using laser pulse shaping Active control of chemical reactions Nature, 2003

65 Making new molecules Hla et al (Berlin) C 12 H 10 Electron Induced Chemistry; Nanotechnology

66 Electron Induced Chemistry; Nanotechnology Chemical Control at the Molecular Level Nature 434, Two-electron dissociation of single molecules by atomic manipulation at room temperature

67 Electron Induced Chemistry; Nanotechnology Chemical Control at the Molecular Level Electron excitation and dissociation of individual oriented chlorobenzene molecules on a Si(111)-7 7 surface at room temperature by a two-electron mechanism that couples vibrational excitation and dissociative electron attachment steps. The first electron interacts with the chlorobenzene molecule; the molecule is left vibrationally excited (specifically, the C−Cl wag mode is excited); the second electron interacts with the molecule before the C−Cl wag mode has fully relaxed, leading to dissociation of the C−Cl bond by DEA;

68 Electron Induced Chemistry; Nanotechnology Chemical Control at the Molecular Level

69 Focussed Electron and Ion Beam Deposition

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74 So What Next ????? Plans for (in Europe) 1.Negative ions in plasmas. Use to tune fragmentation pathways in semiconductor plasmas. 2.Anions may be used to form radicals for surface chemistry.

75 Electron Induced Chemistry; Plan for (in Europe) 1.Tune fragmentation pathways in semiconductor plasmas. Negative ions in plasmas programme Europe with Japan. 2.DEA as a process for nanolithography (electron/positron and photoelectron processing). Surface engineering using STM to manipulate molecules EU programme

76 Electron Induced Chemistry; Plan for (in Europe) 1.Tune fragmentation pathways in semiconductor plasmas. Negative ions in plasmas programme Europe with Japan. 2.DEA as a process for nanolithography (electron/positron and photoelectron processing). Surface engineering using STM to manipulate molecules 3.Electron damage of biomolecules and DNA (electron transport in DNA nanowires).NEW COST IBCT Action

77 Electron Induced Chemistry; Plan for (in Europe) 1.Tune fragmentation pathways in semiconductor plasmas. Negative ions in plasmas programme Europe with Japan. 2.DEA as a process for nanolithography (electron/positron and photoelectron processing). Surface engineering using STM to manipulate molecules EU programme (with Australia). 3.Electron damage of biomolecules and DNA ( electron transport in DNA nanowires) EU Programme. 4.Astrochemistry; low temperature electron processing of ices to probe molecular formation in space;

78 Electron Induced Chemistry; Collaborative programmes (Europe) ESF/COST Electron Controlled Chemical Lithography ESF/COST The Chemical Cosmos ESF/COST IBCT EU Research Infrastructure Europlanet EU Initial Training Network LASSIE VAMDC atomic and molecular database

79 COST is supported by the EU RTD Framework Programme ESF provides the COST Office through an EC contract VAMDC A database of Atomic and molecular data for applications including astronomy.

80 Role for Quantemol This range of applications requires a lot of data !

81 Data overload ? Databases Databases Assembly, intercomparison, error/sensitivity analysis Assembly, intercomparison, error/sensitivity analysis

82 Quantemol N Calculate cross sections ! But low energy so.. Calculate cross sections ! But low energy so.. Combine with higher energy (India, Vinodkumar. Joshipure, Antony) Combine with higher energy (India, Vinodkumar. Joshipure, Antony) Zero to 1000s eV Zero to 1000s eV

83 COST is supported by the EU RTD Framework Programme ESF provides the COST Office through an EC contract

84 COST is supported by the EU RTD Framework Programme ESF provides the COST Office through an EC contract

85 Quantemol Ca n estiamte cross sections for targets experimrntalists don’t want to touch ! Or cant do Ca n estiamte cross sections for targets experimrntalists don’t want to touch ! Or cant do Radicals ( CF x SiH x OH CCCH etc) Radicals ( CF x SiH x OH CCCH etc) But challenge for larger systems DyI 3 But challenge for larger systems DyI 3

86 The team – with thanks UCL and OU Sarah Barnett, Julia Davies, Jon Gingell, Andy Birrell, Nykola Jones, Petra Tegeder Paulo Vieira, Samuel Eden, Paul Kendall, Anita Dawes Philip Holtom, Robin Mukerji, Dagmar Jaksch, Mike Davis, Sarah Webb, Liz Drage, Eva Vasekova, Gosia Smialek, Bhala Sivaraman, Sohan Jeetha Patrick Cahillane, William Stevens. Sylwia Ptasinska, Sam Eden, Jimena Gorfinkiel, Radmila Panajatovic

87 And finally to all my colleagues– with thanks Tilmann Märk, Paul Scheier et al, Universität Innsbruck, Austria David Field, Nykola Jones,Soren Hoffmann University Aarhus, Denmark Eugen Illenberger and group Frei University Berli Stefan Matejcik, Jan D. Skalny, Comenius University, Bratislava Gustavo Garcia, Madrid, Spain Paulo Vieira Lisbon. Portugal Marie Jeanne Hubin Franskin, Jacques Delwishe, Liege, Belgium K Joshipura and M Vinodkumar Sarad Patel university India B Raja Sekhar CAT Indore and BARC India H Tanaka Sophia Univeristy Tokyo and Y Itikawa, Japan And all those others in our EU Collaborations


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