Researchers from the nanoscience research center NanoGUNE (San Sebastian, Spain), the University of Munich (LMU, Germany) and Neaspec GmbH (Martinsried, Germany) have developed a new method for fast and reliable chemical identification of virtually any infrared-active material on the nanometer scale.
An ultimate goal in modern chemistry and materials science is the non-invasive chemical mapping of materials with nanometer scale resolution. Although a variety of high-resolution imaging techniques currently exist, such as electron microscopy or scanning probe microscopy, their chemical sensitivity cannot meet the demands of modern chemical nano-analytics. And despite the high chemical sensitivity offered by optical spectroscopy, its resolution is limited by diffraction to about half the wavelength, preventing nano-scale-resolved chemical mapping.
The team developed an optical technique termed nano-FTIR, 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.
Notably, the nano-FTIR spectra match extremely well with conventional FTIR spectra. The spatial resolution is increased by more than a factor of 300 compared to conventional infrared spectroscopy.
Rainer Hillenbrand, group leader from nanoGUNE, concludes: “The high sensitivity to chemical composition combined with ultra-high resolution makes nano-FTIR a unique tool for research, development and quality control in polymer chemistry, biomedicine and pharmaceutical industry.”
The biodefense and diagnostics world increasingly look to microelectromechanical system (MEMS) and nanotechnology for development of biodetection systems and advanced optical biosensing technology. The nano-scale chemical mapping capabilities demonstrated with Nano-FTIR may help create new materials and devices that can be applied to the fields of medicine, electronics and biomaterials.