MultiView 4000
Application Notes
Dual Probe NSOM and AFM Excitation and Detection of Surface Plasmons on a Waveguide
Two NSOM probes can be used for illumination and collection on plasmon-polariton waveguides. One probe is a lensed fiber to excite the plasmons in the waveguide, where a laser is coupled into this probe, which is in contact with the launching pad of the waveguide. This probe is for excitation purposes and does not scan. A second NSOM probe scanned across the waveguide at different locations to collect the evanescent field and imaging of the surface plasmons distribution.
Shown on the right are a topography (top) and corresponding NSOM (bottom) images at two magnifications collected with multiple probes. The image on right demonstrates the plasmonic propagation distance and the image on right shows the plasmonic location with high resolution.
Near-field Excitation and Apertureless Collection of SPPs
Multiple probes can be used to independently excite and collect light, enabling optimization of each individual probe. In this example on surface plasmon polaritons (SPPs), the left tip is apertured to provide near-field SPP excitation. The apertureless right tip provides near-field scattering and collection of the SPP.
Right: A schematic of this setup is shown.
The apertured probe is required for excitation so that it can produce an evanescent field with a spectrum of k vectors to effectively excite the SPPs on the surface. However, for detection, the apertureless probe is preferred and can operate in tunneling mode in order to scatter the SPPs and directly collect the photons produced by such scattering.
Right: The resulting data is shown where the NSOM data is overlaid onto the 3D topography showing the SPP mode propagation and associated exponential decay.
Electrical & Chemical Properties of a Graphene Bridge between Electrical Pads
A dual probe MV4000 system integrated with a Raman spectromer studied the electrical and chemical properties of a graphene bridge that was connected between electrical pads. Two cantilever electrical probes (Nanonics) were brought down to the electrical pads. The variable electrical voltage was applied to the substrate and the current between the electrical probes through the graphene was measured. The Raman signal was collected from the graphene simultaneously with the electrical measurements.
