Many recent studies have highlighted the possibility to tailor the physical and chemical properties of porphyrin at the molecular level to design novel catalysts, sensors and devices with applications in electronics, opto-electronics, and so forth. In the present work, we study the electronic properties of 2H-Tetraphenylporphyrin (2H-TPP) on iron (Fe) and iron silicide (Fe3Si) onto Si (100) substrate using X-ray and Ultraviolet photoelectron spectroscopy (XPS & UPS). The results revealed that the iron atom is coordinated by TPP molecules on Fe/Si as well as on Fe3Si/Si. XPS results provide evidence of the iron coordination with TPP molecules. The UPS analysis evidenced the fine structure in the electronic spectra related to HOMO states below the Fermi level. 1. Introduction The adsorption of functional molecules on solid substrates has become important in the field of nanoscience and, hence, to exploit the potential of bottom-up strategies the nanostructures are grown in a controlled way. It is known that the position and dimension of the molecular assemblies can be tuned and controlled with high precision down to the atomic level on metals [1–3] and semiconductors [4–7]. Developing technologically robust families of adsorbed assemblies on semiconductor surfaces is challenging, especially because the electronic skeleton of molecules is slightly altered after the adsorption [8, 9]. Organic/inorganic interfaces are intriguing and challenging because of the wide variety of phenomena they exhibit, and these interfaces have evolved as a potential alternative to conventional electronic devices. The flexibility afforded by organic molecular films in terms of modes of deposition, chemical functionalization, molecular mixing, and doping opens a number of routes to tailor the interface properties, which would not be possible with inorganic materials [10]. Porphyrins are a flexible class of molecules with a square symmetry planar core conformation (macrocycle) and two-dimensional conjugated π electron delocalization [11–13]. These organic molecules are one of the most studied systems because of their ability to absorb light, to interact with gases, and their involvement in many biological systems. However, they combine a structure-forming element the porphyrin framework with an active site of the porphyrin core. The intrinsic functionality of porphyrins is given by their ability to bind 1st transition row metal atoms at the centre of the macrocycle to form a metalloporphyrin. Many of these molecules are commercially available or can be produced via metalation
References
[1]
B. C. Stipe, M. A. Rezaei, and W. Ho, “Localization of inelastic tunneling and the determination of atomic-scale structure with chemical specificity,” Physical Review Letters, vol. 82, no. 8, pp. 1724–1727, 1999.
[2]
C. Santato and F. Rosei, “Organic/metal interfaces: seeing both sides,” Nature Chemistry, vol. 2, no. 5, pp. 344–345, 2010.
[3]
M. El Garah, F. Palmino, F. Chérioux et al., “Adsorption of zwitterionic assemblies on Si(111)- : a joint tunneling spectroscopy and ab initio study,” Physical Review B, vol. 85, no. 3, Article ID 035425, 2012.
[4]
G. P. Loplnski, D. D. M. Wayner, and R. A. Wolkow, “Self-directed growth of molecular nanostructures on silicon,” Nature, vol. 406, no. 6791, pp. 48–51, 2000.
[5]
R. J. Hamers, S. K. Coulter, M. D. Ellison, et al., “Cycloaddition chemistry of organic molecules with semiconductor surfaces,” Accounts of Chemical Research, vol. 33, no. 9, pp. 617–624, 2000.
[6]
M. El Garah, Y. Makoudi, F. Palmino et al., “STM and DFT investigations of isolated porphyrin on a silicon-based semiconductor at room temperature,” ChemPhysChem, vol. 10, no. 18, pp. 3190–3193, 2009.
[7]
J.-C. Lin, J.-H. Kim, J. A. Kellar, M. C. Hersam, S. T. Nguyen, and M. J. Bedzyk, “Building conjugated organic structures on Si(111) surfaces via microwave-assisted sonogashira coupling,” Langmuir, vol. 26, no. 6, pp. 3771–3773, 2010.
[8]
K. R. Harikumar, J. C. Polanyi, P. A. Sloan, S. Ayissi, and W. A. Hofer, “Electronic switching of single silicon atoms by molecular field effects,” Journal of the American Chemical Society, vol. 128, no. 51, pp. 16791–16797, 2006.
[9]
K. R. Harikumar, T. Lim, I. R. McNab et al., “Dipole-directed assembly of lines of 1,5-dichloropentane on silicon substrates by displacement of surface charge,” Nature Nanotechnology, vol. 3, no. 4, pp. 222–228, 2008.
[10]
C. W？ll, Ed., Physical and Chemical Aspects of Organic Electronics, Wiley-VCH, Weinheim, Germany, 2009.
[11]
J. L. Hoard, “Some aspects of metalloporphyrin stereochemistry,” Annals of the New York Academy of Sciences, vol. 206, pp. 18–31, 1973.
[12]
K. M. Kadish, K. M. Smith, and R. Gillard, Eds., The Porphyrin Handbook, Academic Press, San Diego, Calif, USA, 2000.
[13]
P. Vilmercati, C. Castellarin-Cudia, R. Gebauer et al., “Mesoscopic donor—acceptor multilayer by ultrahigh-vacuum codeposition of Zn-tetraphenyl-porphyrin and C70,” Journal of the American Chemical Society, vol. 131, no. 2, pp. 644–652, 2009.
[14]
E. Baciocchi, O. Lanzalunga, A. Lapi, and L. Manduchi, “Kinetic deuterium isotope effect profiles and substituent effects in the oxidative N-demethylation of N,N-dimethylanilines catalyzed by tetrakis(pentafluorophenyl)porphyrin iron(III) chloride,” Journal of the American Chemical Society, vol. 120, no. 23, pp. 5783–5787, 1998.
[15]
D. Woehrle, “Porphyrins, phthalocyanines and related systems in polymer phases,” Journal of Porphyrins and Phthalocyanines, vol. 4, no. 4, pp. 418–424, 2000.
[16]
J. M. Gottfried, K. Flechtner, A. Kretschmann, T. Lukasczyk, and H.-P. Steinrück, “Direct synthesis of a metalloporphyrin complex on a surface,” Journal of the American Chemical Society, vol. 128, no. 17, pp. 5644–5645, 2006.
[17]
F. Buchner, V. Schwald, K. Comanici, H.-P. Steinrück, and H. Marbach, “Microscopic evidence of the metalation of a free-base porphyrin monolayer with iron,” ChemPhysChem, vol. 8, no. 2, pp. 241–243, 2007.
[18]
A. Weber-Bargioni, J. Reichert, A. P. Seitsonen, W. Auw？rter, A. Schiffrin, and J. V. Barth, “Interaction of cerium atoms with surface-anchored porphyrin molecules,” Journal of Physical Chemistry C, vol. 112, no. 10, pp. 3453–3455, 2008.
[19]
F. Buchner, K. Flechtner, Y. Bai et al., “Coordination of iron atoms by tetraphenylporphyrin monolayers and multilayers on Ag(111) and formation of iron-tetraphenylporphyrin,” Journal of Physical Chemistry C, vol. 112, no. 39, pp. 15458–15465, 2008.
[20]
G. K. Wertheim and P. H. Citrin, “Fermi surface excitations in X-ray photoemission line shapes from metals,” in Photoemission in Solids I, vol. 26 of Topics in Applied Physics, pp. 197–236, Springer, New York, NY, USA, 1978.
[21]
D. R. Miquita, J. C. González, M. I. N. da Silva et al., “Identification and quantification of iron silicide phases in thin films,” Journal of Vacuum Science and Technology A, vol. 26, no. 5, pp. 1138–1148, 2008.
[22]
V. Kinsinger, I. Dézsi, P. Steiner, and G. Langouche, “XPS investigations of FeSi, FeSi2 and Fe implanted in Si and Ge,” Journal of Physics: Condensed Matter, vol. 2, no. 22, p. 4955, 1990.
[23]
B. Egert and G. Panzner, “Bonding state of silicon segregated to -iron surfaces and on iron silicide surfaces studied by electron spectroscopy,” Physical Review B, vol. 29, no. 4, pp. 2091–2101, 1984.
[24]
M. Pessa, P. Heimann, and H. Neddermeyer, “Photoemission and electronic structure of iron,” Physical Review B, vol. 14, no. 8, pp. 3488–3493, 1976.
[25]
U. Starke, W. Meier, C. Rath, J. Schardt, W. Wei？, and K. Heinz, “Phase transition and atomic structure of an Fe3Si(100) single crystal surface,” Surface Science, vol. 377–379, pp. 539–543, 1997.
[26]
U. Starke, J. Schardt, W. Weiss et al., “Structural and compositional reversible phase transitions on low-index Fe3Si surfaces,” Europhysics Letters, vol. 56, no. 6, pp. 822–828, 2001.
[27]
D. K. Sarkar, X. J. Zhou, A. Tannous, M. Louie, and K. T. Leung, “Growth of self-assembled copper nanostructure on conducting polymer by electrodeposition,” Solid State Communications, vol. 125, no. 7-8, pp. 365–368, 2003.
[28]
D. H. Aue, H. M. Webb, and M. T. Bowers, “Photoelectron spectrum and gas-phase basicity of manxine. Evidence for a planar bridgehead nitrogen,” Journal of the American Chemical Society, vol. 97, no. 14, pp. 4136–4137, 1975.
[29]
Y. Bai, F. Buchner, M. T. Wendahl et al., “Direct metalation of a phthalocyanine monolayer on Ag(111) with coadsorbed iron atoms,” Journal of Physical Chemistry C, vol. 112, no. 15, pp. 6087–6092, 2008.
[30]
J. Xiao, S. Ditze, M. Chen et al., “Temperature-dependent chemical and structural transformations from 2H-tetraphenylporphyrin to copper(II)-tetraphenylporphyrin on Cu(111),” The Journal of Physical Chemistry C, vol. 116, no. 22, pp. 12275–12282, 2012.
[31]
N. Ueno and S. Kera, “Electron spectroscopy of functional organic thin films: deep insights into valence electronic structure in relation to charge transport property,” Progress in Surface Science, vol. 83, pp. 490–557, 2008.
[32]
J. Repp, G. Meyer, S. M. Stojkovic, A. Gourdon, and C. Joachim, “Molecules on insulating films: scanning-tunneling microscopy imaging of individual molecular orbitals,” Physical Review Letters, vol. 94, no. 2, Article ID 026803, 4 pages, 2005.
[33]
P. Panchmata, B. Sanyal, and P. Oppeneer, “GGA + U modeling of structural, electronic, and magnetic properties of iron porphyrin-type molecules,” Chemical Physics, vol. 343, no. 1, pp. 47–60, 2008.
[34]
H. Ishii, K. Sugiyama, E. Ito, and K. Seki, “Energy level alignment and interfacial electronic structures at organic/metal and organic/organic interfaces,” Advanced Materials, vol. 11, no. 8, pp. 605–625, 1999.
[35]
J. C. Rivière, Solid State Surface Science, Vol. 1, edited by M. Green, Marcel Dekker, New York, NY, USA, 1969.
[36]
G. H？lzl and F. K. Schulte, “Work functions of metals,” in Solid Surface Physics, vol. 85-86 of Springer Tracts in Modern Physics, Springer, Berlin, Germany, 1979.
[37]
X. Crispin, V. Geskin, A. Crispin et al., “Characterization of the interface dipole at organic/metal interfaces,” Journal of the American Chemical Society, vol. 124, no. 27, pp. 8131–8141, 2002.
[38]
L. Lindell, M. P. de Jong, W. Osikowicz et al., “Characterization of the interface dipole at the paraphenylenediamine-nickel interface: a joint theoretical and experimental study,” Journal of Chemical Physics, vol. 122, no. 8, Article ID 084712, 2005.
[39]
M. Capone, M. Fabrizio, C. Castellani, and E. Tosatti, “Strongly correlated superconductivity and pseudogap phase near a multiband mott insulator,” Physical Review Letters, vol. 93, no. 4, Article ID 047001, 2004.
