Golzhäuser, A.

Muzik, H.

Naboka, M.

Nefedov, A.

Turchanin, A.

Wöll, Ch.

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In situ UHV growth and XPS/NEXAFS characterization of aromatic self-assembled monolayers on gold substrates A. Nefedov, M. Naboka, Ch. Wöll Karlsruhe Institute of Technology H.Muzik, A. Turchanin,  A. Golzhäuser  University of Bielefeld 58th AVS Symposium, Nashville, Tennessee 2 02.03.2012 Dr. Alexei Nefedov Motivation Preparation Modification Functionalization In situ characterization:  XPS, NEXAFS Janus nanomembranes A. Turchanin, AVS2011,  Talk Thursday  (GR-NS-PS-SS-ThM4) Functional immobilization of protein A. Turchanin et al Adv. Mater. 20 (2008) 471  Electron induced generation of functional groups A. Gölzhäuser et al, Adv. Mater. 13, 806 (2001) A. Turchanin et al, Small 3, 2114 (2007) 58th AVS Symposium, Nashville, Tennessee 3 02.03.2012 SAMs preparation  Dr. Alexei Nefedov manipulator evaporator substrate to in-situ analysis  solution preparation   vapour deposition in vacuum    Immersion of a substrate  (Au, Ag, Si,...)  58th AVS Symposium, Nashville, Tennessee 4 02.03.2012 XPS/NEXAFS endstation @ BESSY II Dr. Alexei Nefedov 58th AVS Symposium, Nashville, Tennessee 5 02.03.2012 NEXAFS Spectroscopy – tool for determination of SAMs molecule orientation Dr. Alexei Nefedov I(,) = A{P(1/3)[1 + (1/2)(3cos2 - 1)(3cos2 - 1)] + + (1 – P)(1/2)sin2} cos() = sin()cos() N. Ballav et al, JACS, 129, 15146, 2007  58th AVS Symposium, Nashville, Tennessee 6 02.03.2012 Coverage determination: thickogram Dr. Alexei Nefedov Is   IO  Ss SO Es EO λO  Intensity substrate Intensity overlayer Intensity infinite substrate Intensity infinite overlayer Kinetic energy Kinetic energy Attenuation length of overlayer electrons 58th AVS Symposium, Nashville, Tennessee 7 02.03.2012 Layout of the experiment Dr. Alexei Nefedov 1. Deposition of NBPT fom Knudsen cell: T=80-100°C, t=1-30min, 1-4 steps , for some samples – additional annealing (T=100°C, t=10 min-10h) 2.   Characterisation   XPS: C1s, N1s, O1s, S2p, Au4f  NEXAFS: C-, N- and O-K edges e- 3.   Irradiation with electrons, E=100 eV, I= 0.5mA, stepwise, t=20 s - 5 min, ttot=20 min, 45 mC/cm2 4.   Characterisation  58th AVS Symposium, Nashville, Tennessee 8 02.03.2012 XPS results Dr. Alexei Nefedov 288 287 286 285 284 283 2821x1062x1063x1064x1065x106 Binding energy, eV   1 ML  0.5 ML   0.25 MLIntensity, a.u.C1s544 542 540 538 536 534 532 530 528 5262x1053x1054x105 Binding energy, eV Intensity, a.u.O1s   1 ML  0.5 ML   0.2 ML410 408 406 404 402 400 398 396 394 392 3906x1057x1058x1059x1051x106  1 ML  0.5 ML   0.25 MLIntensity, a.u.Binding energy, eVN1s58th AVS Symposium, Nashville, Tennessee 9 02.03.2012 C-edge NEXAFS: 0.25ML NBPT/Au Dr. Alexei Nefedov 270 280 290 300 310 320 33001234270 280 290 300 310 320 330-1.5-1.0-0.50.00.51.01.52.02.5 90° 75° 55° 30°  Intensity (arb. units)Photon energy (eV) 90°-55° 75°-55° 30°-55°  Intensity (arb. units)Photon energy (eV)0 10 20 30 40 50 60 70 80 900.00.51.01.52.02.53.03.54.04.55.0 C-edge N-edge  fit @=Intensity, a.u.Incidence angle, 58th AVS Symposium, Nashville, Tennessee 10 02.03.2012 C-edge NEXAFS: 0.5ML NBPT/Au Dr. Alexei Nefedov 270 280 290 300 310 320 33001234270 280 290 300 310 320 330-1.0-0.50.00.51.01.5 90° 75° 55° 30°  Intensity (arb. units)Photon energy (eV) 90°-55° 75°-55° 30°-55°  Intensity (arb. units)Photon energy (eV)0 10 20 30 40 50 60 70 80 901.52.02.53.03.54.04.5  after deposition after annealing  fit @=39Intensity, a.u.Incidence angle, 58th AVS Symposium, Nashville, Tennessee 11 02.03.2012 C-edge NEXAFS: 1ML NBPT/Au Dr. Alexei Nefedov 270 280 290 300 310 320 330012345270 280 290 300 310 320 330-0.50.00.51.0 90° 75° 55° 30°  Intensity (arb. units)Photon energy (eV) 90°-55° 75°-55° 30°-55°  Intensity (arb. units)Photon energy (eV)0 10 20 30 40 50 60 70 80 902.53.03.54.04.5 exp  fit @=61Intensity, a.u.Incidence angle, 58th AVS Symposium, Nashville, Tennessee 12 02.03.2012 Coverage dependence of TDM angle Dr. Alexei Nefedov 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.00102030405060  NBPT Thickness, MLBPT [1] NC-BPT [2] =41°, =39° HS-C7H15 [3] 2. N. Ballav et al, JACS, 129, 15146, 2007  1. A. Turchanin et al, Langmuir, 25, 7342, 2009 3. H.-J. Himmel et al, Langmuir, 13, 602, 1996 flat =90° with =20°  =0°, =39° =41°, =90° 58th AVS Symposium, Nashville, Tennessee 13 02.03.2012 STM study of NBPT on Au(111): from sub-monolayers to 1ML Dr. Alexei Nefedov 0.2 ML  0.5 ML  0.7 ML  0.8 ML  H. Muzik, A. Turchanin, A. Golhäuser , AVS2010  58th AVS Symposium, Nashville, Tennessee 14 02.03.2012 Irradiation: transition from nitro- to amino- functional groups Dr. Alexei Nefedov Bestrahlung: Nitro Amino Umwandlung time nitro amino 58th AVS Symposium, Nashville, Tennessee 15 02.03.2012 1ML NBPT/Au after e-irradiation Dr. Alexei Nefedov 270 280 290 300 310 320 33001234270 280 290 300 310 320 3300.00.5 90° 75° 55° 40° 30°NEXAFS: C1s  Intensity (arb. units)Photon energy (eV) 90°-55° 75°-55° 40°-55° 30°-55°  Intensity (arb. units)Photon energy (eV)0 10 20 30 40 50 60 70 80 903.03.54.0 exp  fit @=50Intensity, a.u.Incidence angle, twist angle =058th AVS Symposium, Nashville, Tennessee 16 02.03.2012 Irradiadion: N- and O-edge NEXAFS results Dr. Alexei Nefedov 400 410 420 430 44002468101214 after deposition after irradiationIntensity, a.u.Photon energy, eVN1s530 540 550 5600.00.51.01.52.02.53.03.54.04.55.0 after deposition after irradiationIntensity, a.u.Photon energy, eVO1s58th AVS Symposium, Nashville, Tennessee 17 02.03.2012 Electron induced generation of functional groups: possible mechanism Dr. Alexei Nefedov F. Haber, Z. Elektrochem. 22, 506 (1898) H.U. Blaser, Science 313, 312 (2006)  58th AVS Symposium, Nashville, Tennessee 18 02.03.2012 Dr. Alexei Nefedov Summary At low coverages NBPT molecules are (almost) parallel to Au substrate, at coverage increase  they start firstly to twist keeping the main molecular axis parallel to the surface. When the twist angle becomes about 40°, NBPT molecules stand up in up-right position forming self-assembled monolayer. After e-irradiation  twist angle becomes 0°, resulting from cross-linking of phenyl rings, but keeping the same tilt angle =39°. At transition from nitro to amino functional groups intermediate functional groups (nitroso, hydroxylamine) are also present.  

In situ UHV growth and XPS/NEXAFS characterization of aromatic self-assembled monolayers on gold substrates

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In situ UHV growth and XPS/NEXAFS characterization of aromatic self-assembled monolayers on gold substrates

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