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Researchers from the nanoscience research center NanoGUNE (San Sebastian, Spain), the university of Munich (LMU, Germany) and Neaspec GmbH (Martinsried, Germany) present a new instrumental development that solves a prime question of materials science and nanotechnology: how to chemically identify materials at the nanometer scale (F. Huth et al., Nano Letters, 2012, DOI: 10.1021/nl301159v).

An ultimate goal in modern chemistry and materials science is the non-invasive chemical mapping of materials with nanometer scale resolution. A variety of high-resolution imaging techniques exist (e.g. electron microscopy or scanning probe microscopy), however, their chemical sensitivity cannot meet the demands of modern chemical nano-analytics. Optical spectroscopy, on the other hand, offers high chemical sensitivity but its resolution is limited by diffraction to about half the wavelength, thus preventing nanoscale resolved chemical mapping.

Nanoscale chemical identification and mapping of materials now becomes possible with nano-FTIR, an optical technique that combines scattering-type scanning near-field optical microscopy (s-SNOM) and Fourier transform infrared (FTIR) spectroscopy. By illuminating the metalized tip of an atomic force microscope (AFM) with a broadband infrared laser, and analyzing the backscattered light with a specially designed Fourier Transform spectrometer, the researchers could demonstrate local infrared spectroscopy with a spatial resolution of less than 20 nm. “Nano-FTIR thus allows for fast and reliable chemical identification of virtually any infrared-active material on the nanometer scale”, says Florian Huth, who performed the experiments.

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