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Title: Quantitative resonant soft x-ray reflectivity of ultrathin anisotropic organic layers: Simulation and experiment of PTCDA on Au

Abstract

Resonant soft X-ray reflectivity at the carbon K edge, with linearly polarized light, was used to derive quantitative information of film morphology, molecular arrangement, and electronic orbital anisotropies of an ultrathin 3,4,9,10-perylene tetracarboxylic dianhydride (PTCDA) film on Au(111). The experimental spectra were simulated by computing the propagation of the electromagnetic field in a trilayer system (vacuum/PTCDA/Au), where the organic film was treated as an anisotropic medium. Optical constants were derived from the calculated (through density functional theory) absorption cross sections of the single molecule along the three principal molecular axes. These were used to construct the dielectric tensor of the film, assuming the molecules to be lying flat with respect to the substrate and with a herringbone arrangement parallel to the substrate plane. Resonant soft X-ray reflectivity proved to be extremely sensitive to film thickness, down to the single molecular layer. The best agreement between simulation and experiment was found for a film of 1.6 nm, with flat laying configuration of the molecules. The high sensitivity to experimental geometries in terms of beam incidence and light polarization was also clarified through simulations. The optical anisotropies of the organic film were experimentally determined and through the comparison with calculations, it wasmore » possible to relate them to the orbital symmetry of the empty electronic states.« less

Authors:
; ; ; ;  [1];  [2];  [3]
  1. IOM-CNR, s.s. 14, Km. 163.5 in AREA Science Park, Basovizza, 34149 Trieste (Italy)
  2. Elettra, s.s. 14, km 163.5 in AREA Science Park, Basovizza, 34149 Trieste (Italy)
  3. Department of Physics, University of Johannesburg, P.O. Box 524, Auckland Park 2006 (South Africa)
Publication Date:
OSTI Identifier:
22675924
Resource Type:
Journal Article
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 145; Journal Issue: 2; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0021-9606
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ANISOTROPY; CROSS SECTIONS; DENSITY FUNCTIONAL METHOD; DIELECTRIC MATERIALS; EXPERIMENTAL DATA; FILMS; GOLD; LAYERS; SIMULATION; SOFT X RADIATION

Citation Formats

Capelli, R., Koshmak, K., Giglia, A., Mukherjee, S., Nannarone, S., Mahne, N., Doyle, B. P., Pasquali, L., E-mail: luca.pasquali@unimore.it, Department of Physics, University of Johannesburg, P.O. Box 524, Auckland Park 2006, and Dipartimento di Ingegneria “Enzo Ferrari,” Università di Modena e Reggio Emilia, Via Vignolese 905, 41125 Modena. Quantitative resonant soft x-ray reflectivity of ultrathin anisotropic organic layers: Simulation and experiment of PTCDA on Au. United States: N. p., 2016. Web. doi:10.1063/1.4956452.
Capelli, R., Koshmak, K., Giglia, A., Mukherjee, S., Nannarone, S., Mahne, N., Doyle, B. P., Pasquali, L., E-mail: luca.pasquali@unimore.it, Department of Physics, University of Johannesburg, P.O. Box 524, Auckland Park 2006, & Dipartimento di Ingegneria “Enzo Ferrari,” Università di Modena e Reggio Emilia, Via Vignolese 905, 41125 Modena. Quantitative resonant soft x-ray reflectivity of ultrathin anisotropic organic layers: Simulation and experiment of PTCDA on Au. United States. doi:10.1063/1.4956452.
Capelli, R., Koshmak, K., Giglia, A., Mukherjee, S., Nannarone, S., Mahne, N., Doyle, B. P., Pasquali, L., E-mail: luca.pasquali@unimore.it, Department of Physics, University of Johannesburg, P.O. Box 524, Auckland Park 2006, and Dipartimento di Ingegneria “Enzo Ferrari,” Università di Modena e Reggio Emilia, Via Vignolese 905, 41125 Modena. Thu . "Quantitative resonant soft x-ray reflectivity of ultrathin anisotropic organic layers: Simulation and experiment of PTCDA on Au". United States. doi:10.1063/1.4956452.
@article{osti_22675924,
title = {Quantitative resonant soft x-ray reflectivity of ultrathin anisotropic organic layers: Simulation and experiment of PTCDA on Au},
author = {Capelli, R. and Koshmak, K. and Giglia, A. and Mukherjee, S. and Nannarone, S. and Mahne, N. and Doyle, B. P. and Pasquali, L., E-mail: luca.pasquali@unimore.it and Department of Physics, University of Johannesburg, P.O. Box 524, Auckland Park 2006 and Dipartimento di Ingegneria “Enzo Ferrari,” Università di Modena e Reggio Emilia, Via Vignolese 905, 41125 Modena},
abstractNote = {Resonant soft X-ray reflectivity at the carbon K edge, with linearly polarized light, was used to derive quantitative information of film morphology, molecular arrangement, and electronic orbital anisotropies of an ultrathin 3,4,9,10-perylene tetracarboxylic dianhydride (PTCDA) film on Au(111). The experimental spectra were simulated by computing the propagation of the electromagnetic field in a trilayer system (vacuum/PTCDA/Au), where the organic film was treated as an anisotropic medium. Optical constants were derived from the calculated (through density functional theory) absorption cross sections of the single molecule along the three principal molecular axes. These were used to construct the dielectric tensor of the film, assuming the molecules to be lying flat with respect to the substrate and with a herringbone arrangement parallel to the substrate plane. Resonant soft X-ray reflectivity proved to be extremely sensitive to film thickness, down to the single molecular layer. The best agreement between simulation and experiment was found for a film of 1.6 nm, with flat laying configuration of the molecules. The high sensitivity to experimental geometries in terms of beam incidence and light polarization was also clarified through simulations. The optical anisotropies of the organic film were experimentally determined and through the comparison with calculations, it was possible to relate them to the orbital symmetry of the empty electronic states.},
doi = {10.1063/1.4956452},
journal = {Journal of Chemical Physics},
issn = {0021-9606},
number = 2,
volume = 145,
place = {United States},
year = {2016},
month = {7}
}