AFM/Raman of Carbon Nanotube

Chemical Mapping Using Raman Microscopy

	AFM Raman of CNT Nanowire on Silicon
The frequency of the Raman band at 1575cm-1 indicates whether the carbon nanotube is at a metallic, semi-conductor, or insulating orientation. Clear difference is observed between the high quality nanotube (red) and the disordered material (green).

	1850 Raman points 180nm distance between points
	Tip IN 405 cm-1
	Tip OUT 405 cm-1
	Difference Raman: 405 cm-1 Peak Intensity

TERS Raman Difference At One Point

3D Stacked View:

Without Interpolation of Z Cross-Sections of 1461cm-1 Raman Band of Polymer Mesas In This Pre-Form of a Contact Lens

The online pixel-by-pixel AFM is invaluable for ultimate correlation of optical sections for correct overlay of Raman optical sections and providing for true chemical distribution as a result of the AFM autofocus which effectively removes topographic contributions to the Raman intensity distribution.

Piezo Force Imaging of Periodically Poled Potassium Titanyl Phosphate PPKTP, using a Doped Diamond Si conductive probe in the contact mode. Contact resonance PFM has been used for imaging of Topographic, Phase and Amplitudes signals.

Height	Phase	Amplitude

Same images in 3D:

Height	Phase	Amplitude

PFM Collage With Topography:

Height-Phase	Height-Amplitude

Nanonics Imaging integrated AFM- micro Raman system highlighted by Azonano staff writers demonstrating the contribution of Negative-Stiffness Vibration Isolators for Improving AFM Measurements.

Nanonics Imaging has been using minus K negative stiffness vibration isolation technologies to provide the ultimate quiet environment for its sensitive combined AFM-Raman systems such as the Nanonics MultiView 4000 AFM system, a sensitive AFM-NSOM that can be combined with micro-Raman imaging capabilities from Renishaw. The basis for the integration of AFM and Raman capabilities is the Nanonics MultiView4000.  The Nanonics integrated AFM-Raman system combines sensitive AFM measurements with relevant chemical information from Raman microscopy, leading to a new era in high-resolution Raman spectroscopy.

We highlight here the work of the group of Prof. Uriel Levy, Hebrew University Israel, showing a simple method for phase mapping characterization of nano photonic structures.  The group showed that by exploiting the intrinsic oscillations of an apertured NSOM probe phase mapping could be achieved.

Typical NSOM measurements reveal the intensity of the light but give no information regarding the complex nature of the measured electromagnetic field.  While other methods allow such measurements they have the drawback of very complicated setups like Hetrodyne and Homodyne setups with complex background removal algorithms.  The proposed method is compact, cost effective, align-free and does not require external modulators. The system can be integrated to an existing NSOM setup in relative ease and has high potential as a characterization tool of various nanophotonic structures.  In this paper, several maps were shown providing significant information about the phase and amplitude of the electromagnetic field within the waveguide.

The figure shows a superimposed Phase NSOM signal on AFM topography.

In the image above we see a phase map of a Si serpentine s-shaped waveguide (blue and red colors). The measurements were obtained with the Nanonics MultiView4000 MultiProbe SPM System integrated with a fiber interferometric setup.   Light is emitted from a laser into a beam splitter sending the majority of light into the silicon waveguide. The NSOM probe was brought into proximity with the waveguide and kept in contact with its surface with intermittent contact. The light was collected by the NSOM tip, combined with the reference beam using a beam splitter and detected by a Photo Detector.

The NSOM probe was modulated at a frequency around 40 KHz, which is the characteristic eigen-frequency of the tuning fork of the tip. Such a relatively low frequency component can be detected and demodulated with relative ease with a standard detector and Lock-In Amplifier.  The demodulated signal is the phase NSOM signal giving the phase map.

The open architecture of the MultiView 4000 combined with the ability to scan the tip are critical elements to the setup.  The ability to keep the sample stationary to the input light while scanning the tip over the structure is a key feature. In this manner the electromagnetic field inside the waveguide is unaffected during the measurement.  This paper is one important example of the key role that NSOM and Nanonics are playing in the field of nano-photonic structure characterization.

For further reading-

Near field phase mapping exploiting intrinsic oscillations of aperture NSOM probe

Liron Stern, Boris Desiatov, Ilya Goykhman, Gilad M. Lerman, and Uriel Levy,

OSA, Optics Express, Vol. 19, Issue 13, pp. 12014-12020 (2011)

Dr. Didier Casse and his team of researchers at the Electronic Materials Research Institute at Northeastern University have recently published Super-Resolution Imaging Using a Three-Dimensional Metamaterials Nanolens, which appeared online in Applied Physics Letters in January, 2010, and went on to become APL's 5th most downloaded paper.