Friday, 27 February 2015 16:15

February 2015 Newsletter

APS, ImagineNano, Image Contest, and Graphene

Visit with Nanonics at these March events

(1) APS, March 2-6, 2015 San Antonio TX,  Booth #660

 

Correlation of Raman and single and multiple layer graphene conductivity as detected with a cryogenic multiprobe AFM with on-line Raman, NSOM, and other SPM modalities

presented by Prof. Aaron Lewis, CEO of NanonicsImaging

Thursday, March 5, 4:42-4:53pm

More on the meeting can be found here.

(2) ImagineNano, March 10-13, 2015 Bilbao Spain, Israel Pavilion

Multi-dimensional characterization of graphene at ultralow temperatures


 

Thursday March 12th in the NanoSpain Chemistry program.

More on the meeting can be found here

Contact us at info@nanonics.co.il to schedule a meeting to discuss your research and instrumentation needs.

2015 Nanonics Website Image Contest


EXCITING NEWS!  Nanonics is launching a new, redesigned website. To celebrate this exciting milestone, Nanonics Imaging is holding an image contest.  Top submissions will be featured on the title banner of our new homepage.  In addition, winners will receive Itunes gift cards. 

Here are the rules for the image contest (or see contest website):

  • You may submit as many as images as you would like
  • Entries must include the original raw data file and the preferred rendering in .jpg or .tif
  • Please include with each image:  Nanonics system used, image caption, scan size, author(s) and affiliation(s)

Please send your image contest submissions to info@nanonics.co.il by March 15, 2015.  Please write "Image Contest Submissions" in the subject line.

By submitting your image, you grant Nanonics Imaging unlimited non-exclusive permission to adapt and use the image on its website, application notes, and other marketing materials/promotions.

GRAPHENE FOCUS

TERS induces and examines reversible graphene single defect

In a beautiful example of work that approaches the ultimate limits of nano-fabrication, a TERS tip has been used to reversibly tailor a graphene surface by inducing defects.  Defects in graphene can break its hexagonal symmetry and affect its properties, so any ability to control defects is important to improving graphene properties.  Also, controlling graphene defects has application potential in phase transformation, recording information, and nanoscale switching.  Thus the ability to control and even reverse defects in graphene has important practical applications.  


 

In this work exploring the origin of graphene defects, the TERS tip performed a double function both by artificially inducing the defect and detecting it.  A MultiView 4000 equipped with nanoparticle-tipped TERS and AFM-TERS feedback induce a reversible defect in the graphene through interaction with the TERS tip; the defect went away when the TERS tip was retracted. TERS spectra are shown below of the tip on (red) and off (black) the graphene surface show new bands (D,D+G) induced by the TERS probe that created the extrinsic deformation on the graphene surface.
 

                          

Access full publication here  [P. Wang et al, Plasmonics, vol 7, p. 555, 2012]

Understanding Graphene with Raman based methods

Nanonics provides a full suite of powerful tools to characterize graphene

For AFM-Raman characterization, Nanonics systems such as the Multiview 2000 provides transparent integration of AFM and Raman without top or bottom AFM optical interference.  Raman maps at single frequencies can then be collected and overlaid on topography maps for the ultimate topographic-chemical correlation


 On the right, a correlated AFM-Raman map of a graphene flake shows the intensity map of the 2676cm-1 single layer band  overlaid onto the 3D topography.  This image reveals that the highest distribution of the single layer in the triangular red zone in the top half of the image.

However, sometimes more sophisticated measurements are necessary to fully characterize graphene.  Methods such as TERS difference spectroscopy, where the difference spectrum is calculated between a far-field Raman and TERS signal, provide superior enhancement of the Raman signal enabling the most accurate characterization and identification.  Using AFM-TERS feedback based methods, TERS difference spectroscopy is straightforward to perform.

In the example on the right, AFM-TERS measurements were performed on a graphene flake on an insulating silicon oxide substrate with a MultiView 2000 and a unique high dielectric contrast gold nanoparticle probe with a defined plasmon resonance.   TERS difference spectroscopy results are shown where a far-field Raman spectrum (black) is collected in addition to the TERS spectrum (Red).  The two are subtracted resulting in a difference spectrum (green).  The difference spectrum (green) shows a symmetric, well-defined peak that unambiguously identifies that region as a single layer of graphene.  Difference spectra collected at other points of this graphene flake identify double and multiple layers of graphene (see application note below).

Click here to read or download the complete application note on TERS and AFM-Raman imaging of graphene.

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