Test sample TSD01 is intended for:
TSD01 consists of large variety of densely packed particles with average diameter around 60 nm. Particles’ shape is not ideally round. Some of them are rather cylindrical, some ones have got vertical walls and sharp corners (like as on the REM photo). These features are necessary to collect enough statistics for further “blind” tip estimation using Deconvolution algorithm.
Qualitative tip’s shape estimation with TSD01
Qualitative tip’s shape estimation could be done by comparison of AFM images of TSD01 surface of different AFM probes. Below you may find AFM images of TSD01, performed by two cantilevers of the same model.
Looking at images’ scales, the one may notice that particles’ height on the left image is more than on the right one. That means that tip #1 penetrates deeper into gaps between particles during the scan. And the tip #1 is just the sharpest one between them both.
Quantitative tip's shape estimation: “Blind” reconstruction of AFM tip’s shape using Deconvolution algorithm
Deconvolution algorithm for AFM surface reconstruction was suggested by J.S. Villarrubia in 1997 and now it is implemented in many different AFM-image-processing programs. It also includes the part, that allows so-called "blind" tip's estimation, when analysing a scan of specific surface program draws tip's profile.
For better understanding of this method let’s imagine an ideal vertical bulk (on the image below) which width is equal to “0”. It’s not difficult to calculate that when a probe passes such an object, its image on AFM topography scan will be just the inverted probe’s shape (a dotted line).
Thus, every particle of topography imaged, which size is comparable to a tip, should hold some information about its real shape. The algorithm of “blind reconstruction” compares shapes of all particles (local maximums) of the topography scan and finds common features between them. On the basis of such comparison it outputs approximated tip’s shape. Reliability of the result depends on particles amount (it should be enough to collect statistics) and their shape (then closer to an “ideal bulk” – than better, as we have seen previously).
Knowing details of "blind" tip's estimation algorithm we could formulate the next criteria to the test sample that could be used for its realization:
Quantitative tip’s shape estimation with TSD01
TSD01 manufacture process determines its physical properties: all particles are being grown chaotically around small, several nanometers, cores. Thus, they have got similar, but very irregular shapes. Some of them may have got sections, close to cylindrical, some of them look to be rounder. They have got many sharp corners too. Writing several dozens of such particles during the same AFM image a tip leaves much information about its true shape from each side. And usually this statistic is enough to get reasonable tip’s images after tip’s “blind” estimation by standard deconvolution procedure.
Below you may find the results of “blind” tip’s shape reconstruction from the AFM scans of TSD01 test structure, which were posted previously:
As the one may notice, the results of tip’s shape estimation correspond to our previously-made suggestion that the probe #1 is sharper than the probe #2.
Full Diamond (FD) cantilevers HA_NC/FD consist of standard polysilicon chips and consoles and high quality single crystal diamond needle grown in CVD process and fixed on a lever. Manufacturing a diamond tip with tip's curvature radius less than 10nm and attaching this tip to our own-made polysilicon lever, together with our partners we're glad to present on the market the very special offer: the highest quality AFM tips for routine measurements for the reasonable prices! Our new probes are remarkable for the next features:
Great utility of FD AFM cantilevers for precise measurements is accompanied by a detailed quality control. After gluing a tip to a lever each cantilever is being observed by SEM before shipment. Thus only good probes reach the customers.
Applications: Scanning sticky biological samples
|Our colleague from University of Nebraska Medical Center, Mohtadin Hashemi, have reported about outstanding FD probes utility for measurements of sticky biological samples. He tried both FD and Si probes for scanning of fibril and globular amyloid aggregates. When standard Si tip could be used only for 2-3 hours (then its surface became too dirty, catching sample's material), FD cantilever didn't show any degradation during 7 hours continous repeated scan of the same area. Images from the both sides were taken with 3 hours difference - no tip's or sample's degradation can be noticed.|
Applications: Less sensitivity to surface charges
|Our experiment have showed that FD cantilevers are less sensitive to effect of image distortion due to surface charges. To the left you may find an image of silver nanoparticles on mica by a standard Si cantilever in low humidity conditions. It took around 1 hour of parameters' adjustment to get this image. The engineer had to decrease contact amplitude of cantilever's oscillation 10 times in respect to free oscillations. To the right you may find a scan of the same surface, obtained by FD probe without any special adjustments. Image is more sharp and particles' sizes are much lower, as they should be in accordance to non-AFM investigation of this sample.|
Chip thickness H: 0,4mm.
Reflective side coating: Au.
Tip's cone angle: < 25 degrees.
Tip's aspect ratio: > 1:5.
Tip's curvature radius: < 10 nm.
Chip has one rectangular spring.
|Cantilever type||A||Typical dispersion|
|Length, L (µm)||124||± 2|
|Width, W (µm)||34||± 3|
|Thickness, H (µm)||1.85||± 0.15|
|Force Constant (N/m)||3.5||±20%|
|Resonant frequency (kHz)||140||± 10%|
***HA_C/FD probe could be produced with another type of HA_NC lever (235 kHz resonance frequency) by request.
Having many-years experience of work in Atomic Force Microscopy field, we know very well how important good environmental conditions are. And today we're glad to present in our assortment the new product line: vibration control equipment from our partners, Ostec-Instruments.
This product line is really new, and not only for ScanSens. While most of present-day vibration isolation platforms are based on piezo- actuators as active elements, our products utilize electromagnetic coils principle. This progressive technology avoids several problems, such as non-linear response and hard construction, peculiar to piezo- based devices. It allows intelligent integration of a vibration control platform depending on building and environmental properties. The same time specially developed construction provides active isolation in all six degrees of freedom.
Already being sold in several institutes, AVOS platforms have showed excellent vibration protection for various AFM and SEM models. During examination at NT-MDT SI in 2017 the engineer could easily get atomic resolution on Solver NEXT device, placed on AVOS AR module, without any additional protection.
Please, don't hesitate to contact us if any questions will appear. Basing on conditions and possible vibration sources of your laboratory we will be glad to find the best solution that will remove noise from your scans.
It's already 7 years have passed since we manufactured our first TERS-active cantilevers, - and their characteristics and results constantly grow up and improve all this time. Just recently NT-MDT SI engineers have showed TERS in liquid on an opaque sample, using our cantilevers.
And now we're glad to present the new product - TERS demonstration, - which would be interesting so for new AFM-Raman researchers as for experienced specialists.
To detect Tip-Enhanced Raman Scattering is a tricky task, which becomes a deal of the independent research for every new type of sample. Before to start such a difficult investigation with the sample targeted it could be reasonable to polish metodology of the experiment with something more simple and reliable. As a starting point the one could took a combination of our TERS-activated cantilevers and specially prepared TERS_S sample. Using this couple experienced engineers from NT-MDT SI get Raman signal enhancement with almost 100% probability.
What could be better to start working with TERS? Only to speak with an experienced AFM-Raman engineer and to see how he gets Raman signal enhancement directly in your lab!
You may find more info about our new product here.
Here at ScanSens GmbH we allways think about how to make recent acheivements in nanoscience more clear and available to everyone. We hope that the new service of TERS demonstration will help our customers to get excellent results in AFM and Raman using other our products, TERS cantilevers and test sample. If any questions appear, please, don't hesitate to contact our sales manager, Evgeniy Lisov (firstname.lastname@example.org).
You're always welcome!