NSOM Modes
Apertureless Non-Interferometric
Apertureless (or scattering s-NSOM) NSOM is an optical method that overcomes optical diffraction limits in order to obtain optical images with nanoscale resolution. Most convential apertureless NSOM systems use sharp metal coated AFM probes illuminated with a far-field optical source. The electrical field is enhanced at the sharp metallized tip (as in the lightning rod effect) and thus the tip acts as the "hot spot". The optical signal scattered from the probe is extracted from the far-field background using probe modulation methods.
Despite of the high optical resolution, this method has some limitations mainly because of the large background signal, artifacts and delicate measurement equipment. For example, for NSOM in collection mode, fluorescence, photo-luminescence and polarization effects cannot be performed using the apertureless technique with one metalized probe and IR far-field illumination. Apertured NSOM can also be a challenge in the IR spectrum.
Nanonics solutions are based on the unique abilities of the single probe and multi-probe scanning microscopes. Nanonics enables one to adopt the system and the probes for specific applications and to meet the researcher’s needs. One example of this is the use of our Thermocouple or Thermo-resistivity probe; by scanning it over the sample, one can probe the IR optical field in the near vicinity of the sample. This is done without the need of introducing illumination on the tip and it allows one to collect a large spectrum of IR. See an application of this technique below.
Our apertureless technique can be combined inside a Cryogenic or High Vacuum chamber along with simultaneous imaging such as in-situ Raman.
Key Features
- Apertureless imaging with photon force (PiFM) in the visible mid-IR & THz
- Apertureless direct temperature mapping of nanoscale plasmonic devices
- Highest force sensitivity
- Apertureless excitation without background using tunnelling can excite luminescence and provides all k vectors and all energies for plasmonic excitation
- Tip Enhanced Raman Scattering
Exemplary Papers
Apertureless Imaging with Photon Force (PiFM) in the Visible mid-IR & THz
Above: Collage of topography with shading photon force amplitude
Nanonics user Aristide Degariu used this picoNewton force sensitivity to image with photon force
Reference: Kohlgraf-Owens, D. C., Greusard, L., Sukhov, S., De Wilde, Y., & Dogariu, A. (2013). Multi-frequency near-field scanning optical microscopy. Nanotechnology, 25(3), 035203.
Read abstract here: http://iopscience.iop.org/article/10.1088/0957-4484/25/3/035203
Measuring the Force of a Single Photon with AFM
Nanonics user Aristide Degariu used this picoNewton force sensitivity to measure the force of a single photon with AFM.
Reference: Kohlgraf-Owens, D. C., Sukhov, S., & Dogariu, A. (2011). Mapping the mechanical action of light. Physical Review A, 84(1), 011807.
Read abstract here: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.84.011807
Apertureless Point Detection of Near-field Photon Flux Without A Large Background With A Point Thermocouple
The thermal probes Linear response at different wavelengths
Reference: Grajower, M., Desiatov, B., Goykhman, I., Stern, L., Mazurski, N., & Levy, U. (2015). "Direct observation of optical near field in nanophotonics devices at the nanoscale using Scanning Thermal Microscopy." Optics express, 23(21), 27763-27775.
Read abstract here: https://www.osapublishing.org/oe/abstract.cfm?uri=oe-23-21-27763
Seen above: Nanonics thermocouple probe
Learn more about Nanonics thermocouple probes:
Apertureless Direct Temperature Mapping of Nanoscale Plasmonic Devices
The steady-state thermal distribution in silicon plasmonic nano-tips is studied numerically and measured experimentally using the approach of scanning thermal microscopy. The Nanonics MV4000 with a Thermal tip was used in order to achieve the high resolution results.
The capability of measuring temperature distribution of plasmonic structures at the nanoscale is shown to be a powerful tool and may be used in future applications related to thermal plasmonic applications such as control liquids heating of, thermal photovoltaic, nanochemistry, medicine, heat-assisted magnetic memories, and nanolithography.
Reference: Desiatov, B., Goykhman, I., & Levy, U. (2014). Direct temperature mapping of nanoscale plasmonic devices. Nano Letters, 14(2), 648–652.
About the Author: Uriel Levy is a Professor in Hebrew University of Jerusalem. He is a world leader in nanophotonics and head of the NanoOpto group. His research is mainly focused on Silicon Photonics, Polarization Optics, Plasmonics and Opto-Fluidics. He is the recipient of The Hebrew University President’s Prize for Outstanding Young Researcher and is a fellow of the Optical Society of America. Professor Levy is an Editor of the journal Optics Express, has published more than 90 scientific articles in leading journals, and serves on the committees of several conferences in the field of opto-electronics.
Read abstract here: https://pubs.acs.org/doi/abs/10.1021/nl403872d
Femto Second PiFM Imaging without Thermal Artifacts
CW laser photon induced force measurements (PiFM) experiments compared with fsec pulsed laser measurements with a Nanonics MV 2000 showing no thermal artifacts.
CW measurements show wavelength dependent PiFM imaging while fsec PiFM is wavelength independent
Reference: Jahng, J., Park, S., Morrison, W. A., Kwon, H., Nowak, D., Potma, E. O., & Lee, E. S. (2017). Nanoscale spectroscopic studies of two different physical origins of the tip-enhanced force in photo-induced force microscopy. arXiv preprint arXiv:1711.02479.
Read abstract here
