Characterization of Thermally Reduced Graphene Oxide by Imaging Ellipsometry

The dispersion functions for the refractive index and the extinction coefficient of single- and multiple-layer graphene oxide samples were measured by imaging spectroscopic ellipsometry in the wavelength range of 350−1000 nm and were compared to previously reported results measured by confocal microscopy. The dispersion functions for thin platelets were also compared to those obtained by standard spectroscopic ellipsometry on a deposit consisting of many overlapping graphene oxide layers. Changes were observed in both the thickness of the deposits and the values of the dispersion parameters following heating. A model is proposed to explain these observations, based on the removal of water between the graphene-oxide layers upon thermal treatment.

[1]  K. Yoshizawa,et al.  The Role of Orbital Interactions in Determining the Interlayer Spacing in Graphite Slabs , 2000 .

[2]  A. Djurišić,et al.  Optical properties of graphite , 1999 .

[3]  S. Stankovich,et al.  Graphene-silica composite thin films as transparent conductors. , 2007, Nano letters.

[4]  Yihong Wu,et al.  Graphene thickness determination using reflection and contrast spectroscopy. , 2007, Nano letters.

[5]  S. Stankovich,et al.  Preparation and characterization of graphene oxide paper , 2007, Nature.

[6]  L. Ward,et al.  The Optical Constants of Bulk Materials and Films , 1988 .

[7]  Albert A. Michelson,et al.  Studies in Optics , 1995 .

[8]  H. Macleod,et al.  Thin-Film Optical Filters , 1969 .

[9]  Kang L. Wang,et al.  A chemical route to graphene for device applications. , 2007, Nano letters.

[10]  Harland G. Tompkins,et al.  A User's Guide to Ellipsometry , 1992 .

[11]  Martina Hausner,et al.  Simple Approach for High-Contrast Optical Imaging and Characterization of Graphene-Based Sheets , 2007, 0706.0029.

[12]  D. Beaglehole,et al.  Performance of a microscopic imaging ellipsometer , 1988 .

[13]  Klaus Kern,et al.  Electronic transport properties of individual chemically reduced graphene oxide sheets. , 2007, Nano letters.

[14]  P. Kim,et al.  Experimental observation of the quantum Hall effect and Berry's phase in graphene , 2005, Nature.

[15]  R. Azzam,et al.  Ellipsometry and polarized light , 1977 .

[16]  Andre K. Geim,et al.  Two-dimensional atomic crystals. , 2005, Proceedings of the National Academy of Sciences of the United States of America.

[17]  N. Wingreen,et al.  Use of dielectric functions in the theory of dispersion forces , 2005 .

[18]  A. Neto,et al.  Making graphene visible , 2007, Applied Physics Letters.

[19]  G. Wallace,et al.  Processable aqueous dispersions of graphene nanosheets. , 2008, Nature nanotechnology.

[20]  Andre K. Geim,et al.  Electric Field Effect in Atomically Thin Carbon Films , 2004, Science.

[21]  S. Stankovich,et al.  Stable aqueous dispersions of graphitic nanoplatelets via the reduction of exfoliated graphite oxide in the presence of poly(sodium 4-styrenesulfonate) , 2006 .

[22]  E. Palik.  Handbook of Optical Constants of Solids , 1997 .

[23]  Masahiro Fujiwara,et al.  Thin-film particles of graphite oxide 1:: High-yield synthesis and flexibility of the particles , 2004 .

[24]  S. Stankovich,et al.  Graphene-based composite materials , 2006, Nature.

[25]  K. Müllen,et al.  Transparent, conductive graphene electrodes for dye-sensitized solar cells. , 2008, Nano letters.