Spectroscopic Near-Field Imaging from Cancer to Graphene Plasmons

William S.Hart
July 26th, 2018 WILLIAM S. HART Imperial College London

Mid-IR spectroscopy (λ ≈ 5 to 12μm) is widely used to identify chemicals. It exploits the fact that molecules absorb light at certain frequencies that are particular to their structure. Traditional methods have high spectral resolution, but are diffraction limited to large spatial resolutions of ~10μm, and so can only allow for the study of e.g. groups of cells. Scattering-type Scanning Near-field Optical Microscopy (s-SNOM) offers a way of beating the dif-fraction limit. S-SNOM uses an extremely sharp probe to scatter incident light in such a way that the information of the optical near-field is collected in a region only ~10nm in diameter. The tip is raster scanned to produce an optical image with resolution of ~λ/1000 in the mid-IR. Typically, this has been used only in solid state or highly controlled biological systems, such as isolated proteins on sili-con.

This talk presents the first near-field images of single cells, and the ability to map chemical compo-sition of unaltered samples at unprecedented (nanoscale) spatial resolution. This talk will include ex-amples of nanoscale mapping of the anti-cancer drug bortezomib within a single human myeloma cell, as well as infrared nano-imaging of sub-cellular organelles. The possibility of live-cell nano-imaging utilizing metamaterial superlenses will also be discussed.

Finally, the application of s-SNOM to graphene plasmonics will be discussed with demonstration of wide-band, fine-coverage measurements of plasmon dispersion and intriguing “hotspots” around bi-layer graphene strips.

Seminar, July 26, 2018, 12:00. ICFO’s Seminar Room

Hosted by Prof. Frank Koppens