Sincrotrón ALBA
Rainer Hillenbrand from CIC nanoGUNE Consolider, San Sebastian
Cuándo
Información de contacto
Salvador Ferrer
With the development of scattering-type scanning near-field optical microscopy (s-SNOM) [1] and nanoscale-resoved FTIR spectroscopy [2,3], the analytical power of visible, infrared and THz imaging has been brought to the nanometer scale. The spatial resolution of about 10 - 20 nm opens a new era for modern nano-analytical applications such as chemical identification, free-carrier profiling and plasmonic vector near-field mapping.
s-SNOM is based on elastic light scattering from atomic force microscope tips. Acting as an optical antenna, the tip convert the illuminating light into strongly concentrated near fields at the tip apex (nanofocus), which provides a means for localized excitation of molecule vibrations, plasmons or phonons in the sample surface. Recording the tip-scattered light subsequently yields nanoscale-resolved optical images, beating the diffraction limit in the infrared spectral range by more than two orders of magnitude.
Using broadband IR illumination and Fourier-transform spectroscopy of the tip-scattered light [2,3], we recorded IR spectra with 20 nm spatial resolution (nano-FTIR). Near-field images and near-field absorption spectra of molecular vibrations in mid-infrared fingerprint region allow for chemical mapping, identification of polymer [3] and protein [4] nanostructures, and for quantitative measurement of the complex-valued local dielectric function, among others. In the field of nanophotonics, we apply s-SNOM for launching and mapping of ultra-confined electromagnetic waves (plasmons) in graphene [5,6].
[1] F. Keilmann, R. Hillenbrand, Phil. Trans. R. Soc. Lond. A 362, 787 (2004)
[2] F. Huth, et al., Nature Mater. 10, 352 (2011)
[3] F. Huth, et al., Nano Lett. 12, 3973 (2012)
[4] I. Amenabar, et al., Nat. Commun. 4:2890 (2013)
[5] J. Chen et al., Nature 487, 77 (2012)
[6] P. Alonso Gonzalez et al., Science 344, 1369 (2014)