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10/31/10

Measuring instruments in nanotechnology

Major testing and metrology instruments for nano materials are the following:
Testing/ Characterization instruments:
i) Nano-Indenter/Hardness tester
ii) Spectroscopy to ascertain the chemical composition of nanomaterials
Metrology instruments:(see old posts of this blog for a detailed report)
i) Atomic Force Microscopy (AFM)
ii) Transmission Electron Microscopy (TEM)
iii) Scanning Electron Microscopy (SEM)
The procedure of sample preparation is a critical step for AFM, SEM and TEM but every single step makes a difference.
TEM: Here sample preparation is very time-consuming and complicated.
SEM: Here samples are easier to prepare, however the requirement for conductivity adds some difficulty. Scanning electron microscope has a magnification range from 15x to 200,000x (reached in 25 steps) and a resolution of 5 nanometers.
AFM: The AFM is similar to electron microscope techniques, SEM and TEM, where proper sample preparation is the key to get reliable data. Here sample preparation is easier because samples do not have to be conductive. However, there are very important criteria to be met in order to do AFM imaging.
Nano-Indenter/Hardness tester(NanoTest nanoindentation module of Micro Materials Ltd )
To measure nanomechanical properties, a very small calibrated diamond probe is brought into contact with the sample surface and a load is applied by means of a coil and magnet located at the top of the pendulum. The resultant displacement of the probe into the surface is monitored with a sensitive capacitive transducer and displayed in real time as a function of load. This produces accurate nano-hardness and modulus results.
Measurable properties are:
• Adhesive failure
• Creep and relaxation
• Contact fatigue
• Fracture toughness
• Impact resistance
• Loss and storage moduli
• Nanoscale wear resistance
• Stress-strain data
• Surface friction and topography
• True thin film hardness and modulus
NanoSpectralyzer (ANF)
NanoSpectralyzer is a unique automated fluorimetric analyzer manufactured by Applied NanoFluorescence (ANF) based on the most advanced research in nanotube spectroscopy. The near-infrared emission spectra of nanotube samples serve as compositional "fingerprints." One can therefore use spectrofluorimetry to deduce detailed information about the compositions of bulk samples, which invariably contain mixtures of (n,m) species.
Applications
This instrument combines a specialized optical system with custom software to enable efficient, turn-key analyses of bulk SWNT samples. The NanoSpectralyzer is valuable for tuning the process conditions in SWNT growth reactors, for quality control, for guiding nanotube sorting and separation methods, and for a wide range of research applications that require detailed compositional data on a rapid time scale
Compositional analysis
The sample can be prepared in a few minutes by ultrasonically dispersing ca. 0.01 mg of a raw solid SWNT specimen into a small volume of aqueous surfactant solution. A few drops of this suspended specimen are then placed into the NanoSpectralyzer’s sample cell. An automated sequence of data collection and interpretation quickly provides the operator with a detailed compositional analysis.
Semiconducting content and diameter distribution
The sample is first irradiated with light from diode lasers of pre-selected wavelengths, and the resulting fluorescence emission is collected by specialized optics, dispersed in a spectrograph, detected by a multichannel near-IR sensor, and recorded by the instrument’s computer. The resulting spectral data are automatically analyzed, using established findings in SWNT optical spectroscopy, to provide a detailed description of the semiconducting SWNT content of the sample. Specific (n,m) species are identified along with their apparent relative abundances. The findings are also displayed in the form of a diameter distribution.
Sample purity
The NanoSpectralyzer also records near-infrared absorption spectra, which are automatically compared to emission data to characterize the sample purity in terms of unbundled and undamaged SWNT.
Spectrofluorometer (NanoLog)
Nanotechnology requires specialized fluorescence spectroscopy for nanomaterials when irradiated under visible or near-IR light. The spectrofluorometers are specifically designed for research in nanotechnology and the frontiers of nanomaterials and detects fluorescence in the near-IR from 800 to 1700 nm (optional multi-channel detection to 2 µm, single-channel detection to 3 µm), with visible and UV options possible. Classifications of SWNTs and energytransfer calculations can be carried out. Complete spectrum can be scanned as fast as a few milliseconds, and a full excitation-emission matrix scan can be taken in as little as seconds. Can be used to resolve mixtures of quantum dots simultaneously.
Raman Microscopy (HORIBA Jobin Yvon range)
Raman spectrometers and microscopes give highest definition images for a broadest range of samples and high resolution options probe subtle phase and structural properties listed below.
• Nano-materials - SWCNT, Boron Nitride, breathing mode, chirality, purity
• Polymers - homogeneity and phase
• SAM and LB films - structure and composition
• True confocality
• High resolution
• Multi-wavelength
• Raman and NIR PL
• Combined micro Raman and FTIR
• Raman at extreme conditions
Particle Size Analyser (HORIBA LB550)
Nanomaterials particle size characterization from nm to micron scale, analysis of emulsions or suspensions within a large range of concentration without dilution can be done using unique built-in viscometer probe with a high degree of accuracy.
Various applications include:
• Inks, painting pigments
• Ceramics, material sciences
• Cosmetics, Pharmaceuticals
• Bio materials
• Polymers
• Food

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