The OneView® IS camera offers the highest performance and the most rapid operation of all the fiber-coupled Gatan cameras. It is capable of displaying and saving 16 MP images to disk at up to 25 fps, making it ideally placed for the observation of dynamic details in in-situ TEM experiments.
Context
A wide range of science and technology applications are reliant on the nucleation and growth of crystals via the self-organization of atoms or molecules. These phenomena have been studied for decades, but the experimental observation of these processes at the atomic scale continues to pose a number of challenges.
One promising means of observing and recording the emergence of crystal nuclei lies in the containment of nucleating species within carbon nanotubes (CNT). This approach contains the species’ position during nucleation and subsequent growth.
This containment enables the more straightforward application of in-situ transmission electron microscope (TEM) techniques able to capture dynamics in real-time while maintaining the highest possible spatial resolution.
Materials and Methods
An aggregate of aminated conical CNTs was soaked in aqueous NaCl before being dried at room temperature in vacuo. Next, the sample was observed using an image-corrected JEOL JEM-ARM200F, which was operated at 80 kV with a dose rate of 4000 e-/Å2/s.
A OneView IS camera, operating at 25 fps and 2048 x 2048 pixels, was used to continuously record this data.
Summary
It was possible to observe the repeated nucleation and growth of NaCl nanocrystals in a single conical CNT as part of a single continuous in-situ video acquisition. This was recently published in the journal ACS.
Figure 1 displays data from the third nanocrystal in the video, highlighting six of the 3300+ individual frames. The complete video records the formation of a total of nine nanocrystals over 132 seconds.
Figure 1. Six frames from a 132 s video, showing nucleation and growth of a single NaCl nanocrystal. The full video which covers the nucleation and growth of 9 crystals can be found on YouTube (https://www.youtube.com/watch?v=SK6PCPVPja8). Image Credit: Gatan Inc.
The researchers were able to use this setup to measure the cross-sectional area of the NaCl crystallite from the in-situ video frames. They discovered stochastic variation in the measured size throughout nucleation, followed by primarily quantized values during growth.
The capture of high-quality image frames with the rapid camera and the constrained position of the nanocrystal within the CNT allowed these detailed measurements to be made.
As the process was repeated nine times during one video, it was also possible to determine both the average nucleation time and the variation in nucleation times.
This information has been sourced, reviewed and adapted from materials provided by Gatan Inc.
For more information on this source, please visit Gatan Inc.