Quantitative Measurement of Local Infrared Absorption and Dielectric Function with Tip-Enhanced Near-Field Microscopy.

Scattering-type scanning near-field optical microscopy (s-SNOM) and Fourier transform infrared nanospectroscopy (nano-FTIR) are emerging tools for nanoscale chemical material identification. Here, we push s-SNOM and nano-FTIR one important step further by enabling them to quantitatively measure local dielectric constants and infrared absorption. Our technique is based on an analytical model, which allows for a simple inversion of the near-field scattering problem. It yields the dielectric permittivity and absorption of samples with 2 orders of magnitude improved spatial resolution compared to far-field measurements and is applicable to a large class of samples including polymers and biological matter. We verify the capabilities by determining the local dielectric permittivity of a PMMA film from nano-FTIR measurements, which is in excellent agreement with far-field ellipsometric data. We further obtain local infrared absorption spectra with unprecedented accuracy in peak position and shape, which is the key to quantitative chemometrics on the nanometer scale.

[1]  F. Keilmann,et al.  Effect of tip modulation on image contrast in scattering-type near-field optical microscopy , 2005 .

[2]  Oliver G Schmidt,et al.  Intersublevel spectroscopy on single InAs-quantum dots by terahertz near-field microscopy. , 2012, Nano letters.

[3]  R. Carminati,et al.  Image formation in near-field optics , 1997 .

[4]  Xiaoji G. Xu,et al.  Pushing the Sample-Size Limit of Infrared Vibrational Nanospectroscopy: From Monolayer toward Single Molecule Sensitivity. , 2012, The journal of physical chemistry letters.

[5]  R. Hillenbrand,et al.  Enhanced resolution in subsurface near-field optical microscopy. , 2012, Optics express.

[6]  Fritz Keilmann,et al.  Mid-infrared near-field spectroscopy. , 2009, Optics express.

[7]  G. Scoles,et al.  Detection of Hybridization on Nanografted Oligonucleotides Using Scanning Near-Field Infrared Microscopy , 2010 .

[8]  Byung-Gyu Chae,et al.  Mott Transition in VO2 Revealed by Infrared Spectroscopy and Nano-Imaging , 2007, Science.

[9]  Fritz Keilmann,et al.  Mid-infrared Frequency Comb Spanning an Octave Based on an Er Fiber Laser and Difference-Frequency Generation , 2013, 2013 Conference on Lasers & Electro-Optics Europe & International Quantum Electronics Conference CLEO EUROPE/IQEC.

[10]  K. Kern,et al.  Full simulations of the apertureless scanning near field optical microscopy signal: achievable resolution and contrast. , 2009, Optics express.

[11]  Christoph Lienau,et al.  Apertureless near-field optical microscopy: Tip–sample coupling in elastic light scattering , 2003 .

[12]  F. Keilmann,et al.  Near-field probing of vibrational absorption for chemical microscopy , 1999, Nature.

[13]  F. Keilmann,et al.  Complex optical constants on a subwavelength scale. , 2000, Physical review letters.

[14]  D. Lynch,et al.  Handbook of Optical Constants of Solids , 1985 .

[15]  J. Aizpurua,et al.  Substrate-enhanced infrared near-field spectroscopy. , 2008, Optics express.

[16]  J. Aizpurua,et al.  Terahertz near-field nanoscopy of mobile carriers in single semiconductor nanodevices. , 2008, Nano letters.

[17]  F. Keilmann,et al.  Phonon-enhanced light–matter interaction at the nanometre scale , 2002, Nature.

[18]  M. Schnell,et al.  Infrared-spectroscopic nanoimaging with a thermal source. , 2011, Nature materials.

[19]  R. Hillenbrand,et al.  Analytical model for quantitative prediction of material contrasts in scattering-type near-field optical microscopy. , 2007, Optics express.

[20]  Yohannes Abate,et al.  Nanoscale infrared absorption spectroscopy of individual nanoparticles enabled by scattering-type near-field microscopy. , 2011, ACS nano.

[21]  E. Korte,et al.  Infrared Spectroscopic Ellipsometry , 2006 .

[22]  F. Keilmann,et al.  Performance of visible and mid‐infrared scattering‐type near‐field optical microscopes , 2003, Journal of microscopy.

[23]  F. Keilmann,et al.  Broadband-infrared assessment of phonon resonance in scattering-type near-field microscopy , 2011 .

[24]  Thomas Taubner,et al.  Nanoscale-resolved subsurface imaging by scattering-type near-field optical microscopy. , 2005, Optics express.

[25]  K. Gaikovich,et al.  Subsurface near-field scanning tomography. , 2007, Physical review letters.

[26]  F. Keilmann,et al.  Nanoscale polymer recognition by spectral signature in scattering infrared near-field microscopy , 2004 .

[27]  Yusuke Kajihara,et al.  Nano-FTIR chemical mapping of minerals in biological materials , 2012, Microscopy and Microanalysis.

[28]  M. Allegrini,et al.  Artifact-free near-field optical imaging by apertureless microscopy , 2000 .

[29]  Antonio H. Castro Neto,et al.  Near-field spectroscopy of silicon dioxide thin films , 2011, 1110.4927.

[30]  Gilbert C. Walker,et al.  Imaging secondary structure of individual amyloid fibrils of a β2-microglobulin fragment using near-field infrared spectroscopy. , 2011, Journal of the American Chemical Society.

[31]  Thomas Taubner,et al.  Infrared spectroscopic mapping of single nanoparticles and viruses at nanoscale resolution. , 2006, Nano letters.

[32]  E. Bakkers,et al.  Nanoscale free-carrier profiling of individual semiconductor nanowires by infrared near-field nanoscopy. , 2010, Nano letters.

[33]  A full quantum theory of parametric down conversion and its application to coincidence measurements , 2005 .

[34]  A. Zayats,et al.  Nano-optics and near-field optical microscopy , 2009 .

[35]  T. Taubner,et al.  Quasi-analytical model for scattering infrared near-field microscopy on layered systems. , 2012, Optics express.

[36]  P. Griffiths.  Fourier Transform Infrared Spectrometry , 2007 .

[37]  F. Keilmann,et al.  Nano-FTIR absorption spectroscopy of molecular fingerprints at 20 nm spatial resolution. , 2012, Nano letters.

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

[39]  George C. Schatz,et al.  The journal of physical chemistry letters , 2009 .