Summary of TEM Technique :

Principle :

• A high velocity electron beam is generated and accelerated under high vacuum, it is focused by condenser lens (electromagnetic bending of electron beam) onto specimen.
• Electrons are transmitted through the specimen.
• On the way through the specimen some parts of the material stop or deflect electrons more than other parts.
• The electrons are collected from below the sample onto a phosphorescent screen or through a camera for viewing images. The regions in which electrons do not pass through the specimen the image is dark.
• Where electrons are un-scattered, the image is brighter, and there are a range of greys in between depending on the way the electrons interact with and are scattered by the sample.

Summary of Technique :

• The technique determine the size distribution profile of small particles in suspension or polymers in solution.
• A monochromatic light source is shot through a polarizer and into a sample. The scattered light goes through a second polarizer and is collected by a photomultiplier.
• By repeating the process in short-time interval, the scattered pattern can be analyzed by an autocorrelator to analyze the light intensity profile of each spot.

Summary of Technique :

• Single particle Inductively Coupled Plasma Mass Spectrometry (sp-ICP-MS) is a special type of Inductively Coupled Plasma Mass Spectrometry (ICP-MS) technique developed for the characterization of individual nanoparticles (NPs) in suspension.
• By flowing solutions containing single NPs or their agglomerates at appropriate concentration (about 10​6 particles/mL) into the inductively coupled plasma (6000-10000 K), each NP will produce an ion cloud which will cause a pulse of mass signal related to the diameter of a NP.
• The sp-ICP-MS can overcome limitations of electron microscopy which requires dry samples, by directly analyzing NPs in liquid suspensions with high throughput to provide composition, mass, and diameter information for thousands of NPs. Moreover, by directly measuring mass of each NP, the sp-ICP-MS minimizes environmental parameters (e.g., temperature and vibration) often observed in other NP characterization methods based on the brownian motion of NPs, such as NTA and DLS

Summary of Technique :

• Nanoparticle Tracking Analysis (NTA) ​tracks light signals from small particles in the suspension using a microscope equipped with charge-coupled device (CCD) or in the suspension using a microscope equipped with charge-coupled device (CCD) or scientific complementary metal-oxide-semiconductor (sCMOS) camera over multiple frames.
• Nanoparticles (NPs) in suspension move under ​Brownian motion​. This motion is related to the particle size based on the ​Stokes-Einstein equation​.
• NTA software adopts this equation to estimate the size distribution and concentration of all types of nanoparticles at 10 nm to 2000 nm in diameter and 10​6 to 10​9 particles per mL. For bimodal mixture samples, NTA ​can distinguish size differences of 25% ​(1:1.25 ratio). Thus, compared to the more commonly used DLS (​Dynamic Light Scattering​) technique, NTA is able to measure the ​hydrodynamic size of NPs with better size resolution in a small concentration range, although the applicable size range is narrower than DLS technique.