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Wednesday, 29 January 2014 13:55

January 2014 Newsletter

 
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January 2014 - In This Issue:
Research Focus: Tuning fork probes and feedback
User news: Detection of near-field optical forces
Nanonics at Photonics West
Meet our staff member Rimma Dechter
Tuning fork probe

Tuning fork feedback mechanism for ultimate force sensitivity

 

Tuning forks offer significant advantages and increased sensitivity over conventional Si probes in large part due to their high quality factors (Q of 10x and higher.)   Tuning forks in force spectroscopy have especially begun to show exciting results that push the measurement's possibilities.  Over the last decade, Nanonics has developed instruments using a NanoToolKit of such probes that are increasingly being used with on-line force spectroscopy.  A demonstration of the force sensitivity of these probes is the measurement of 1.6 pN for the force of a single photon. [D. C. Kohlgraf-Owens et al "Mapping the mechanical action of light," Phys. Rev. A 84, 011807R (2011)]

 

Besides force sensitivity, tuning forks offer other advantages over optical beam deflection and conventional Si probes.  Tuning forks have much stiffer (spring constant of ~2600 N/m and greater) than standard silicon cantilevers.  As a result, the problem of "jump to contact" instability that limits the optical beam deflection based feedback methods is eliminated, and this permits the study of forces in the proximal 10-20 nm above a surface.  Smooth approach curves together with lack of adhesion ringing upon withdrawal is combined with additional advantages of no feedback laser interference; these features are important for semiconductor electrical probing and combinations of AFM with Raman spectroscopy that Nanonics has pioneered.  Furthermore, tuning forks in force spectroscopy enable the point of contact with the surface to be accurately measured for the first time.  For all these reasons and its ease of use, tuning forks are becoming an ideal choice for new horizons in experiments requiring the ultimate tip-sample control stability and force sensitivity from areas of bioimaging, to physics of devices, and to single molecule and polymer spectroscopy.

 
Topography color coded with ampl. measured at optical driving frequency
USER NEWS - Detection of near-field optical forces
 

The power and sensitivity of tuning fork feedback was demonstrated in a recent groundbreaking publication in high resolution apertureless imaging by Prof. Aristide Dogariu's group at University of Central Florida.  Using a Nanonics Multiview 4000 system, his team mapped near-field optically induced forces with sub wavelength spatial resolution (Kohlgraf-Owens et al., Nanotechnology, 25, 034203 [2014]). The scientists describe a new method, multifrequency NSOM, performed with tuning forks/tuning fork feedback and cantilever probes/optical beam deflection feedback.   By exciting the probe's oscillation at two difference frequencies, they measured the amplitude and phase  at the optical modulation frequency on a gold nanosphere sample (see image on right) revealing  an amplitude that was lowest over the gold pads, moderate over the glass, and highest near the edges.  The method opens a new horizon of apertureless imaging of optical fields with very high spatial resolution over a large range of wavelengths - including far-IR and THz - and it can be accomplished without using photodetectors, a regime that to-date lacks a competitive alternative for detection!  Professor Aristide comments "We are excited about the potential of multi-frequency NSOM for using photonic forces for apertureless imaging of optical fields in a wide variety of wavelength regimes from the visible to the IR."

Nanonics at Photonics West
 
Nanonics founder and CEO Aaron Lewis, a pioneer in near-field optics, will be at Photonics West. Please email us at info@nanonics.co.il to schedule a discussion and time to meet with him.
 
Professor Lewis is presenting on a variety of topics in February in San Francisco:

1) Sunday, 5:50pm, BIOS 8939-11 (ORAL) "Understanding the TERS effect with an on-line tunneling and force feedback using multiprobe AFM/NSOM with Raman integration
2) Monday, 2:50pm, OPTO 8992-24 (ORAL) "Combined far-field and multiprobe near-field imaging of hybrid photonic devices"
3) Monday, 4:20pm, OPTO 9006-16 (ORAL) "Addressing the inverse problem of imaging:  A noniterative exact solution fo rphae in imaging based on microHolography"
4) Wednesday, 6:00pm, OPTO 8988-64 (POSTER) "Piezoforce and contact resonance microscopy correlated with Raman spectroscopy applied to a non-linear optical material and to a lithium battery material"
5) Thursday, 11:30am, OPT 8999-39 (ORAL) "Ultrasensitive force detection of photonic phenomena with tunin fork based frequency modulation"
Meet Nanonics staff!
Welcome to our newest segment in our newsletter where we will be profiling a member of our staff.  We start this month with Dr. Rimma Dechter, a name that is familiar to many Nanonics customers.

Current position at Nanonics:  Manager of Analytical Services. In this role Rimma heads the department that makes measurements on customer samples in the wide variety of characterization needs Nanonics offers from conventional scanning probe microsopy to near field and Raman measurements to multiple probe experiments.
Academic Background:  PhD in Applied Physics from Hebrew University
Family:  married + 3 kids
Hobbies:  genealogy
What I like about working at Nanonics:  The aspect I enjoy the most is the tremendous amount of innovation that goes on in our company to meet customers needs. It is exciting to interact with customers and learn about their instrumentation requirements for their research; I then work with my colleagues to develop new, out of the box solutions to meet their needs.
 
Where are you presenting your research?
Please let us know where you are presenting your research and we will be happy to share the news!
For more information, please contact us at info@nanonics.co.il or call us at +972-2-678-9573, (US toll free 1-800-289-7162)

 way to increase sensitivity in TERS experiments from complicated biological samples by providing another platform for preparing complex biological molecules that can be probed by the ultrasensitive TERS method.

© 2017 Nanonics Imaging Ltd.

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