We are currently making a science video series about scanning electron microscopy studies. In these videos we discuss the sample preparation and show how things actually look like in the microscopic scale.
Videos can be seen in our YouTube channel.
The scanning electron microscopy images made in these studies are uploaded to our gallery.
What Does a fly look like under the scanning electron microscope? In this video we will explain how biological samples are prepared for scanning electron microscopy (SEM) studies. We will also take some images of the eye, leg, mouth and wing of the fly.
How and why do charged particles cause corrosion of materials in space? This is a question asked by many spacecraft engineers and the answer is not so simple. Namely, there is a whole zoo of different particles and every single one of them interacts with the matter in a unique way. The general rule however is that particles which have a higher mass, charge and velocity, cause more damage. For instance, electrons have a negative charge and in a scanning electron microscope they travel at about 20% of the speed of light but they hardly damage the studied substrate. Ions however have not only a charge but also a lot of mass and therefore they can also cause serious damage if their velocity is sufficient. A completely different story is with antimatter particles such as positrons and anti-protons. When these hit regular matter, then both the particle and the surface of regular matter is converted into energy in the form of gamma radiation. This radiation however can ionize the nearby matter and also do serious damage to electronics, which is shielded from particles but not from gamma rays. High energy radiation is also created when regular charged particles such as protons and electrons interact with the matter as the excess energy is released as braking light (bremsstrahlung), when the high velocity of the particle suddenly changes to zero upon hitting the surface of a material. Anyhow, the spacecrafts are constantly being bombarded with different particles and this slowly degrades the surface of the material and the resulting radiation also has a devastating effect on the electronics. Learn more by watching our new science video:
Atomic oxygen is one of the leading candidates which causes the degradation of materials in space. That’s because atomic oxygen is highly reactive and will oxidize anything that can be oxidized. This means that most vulnerable to this type of corrosion are polymers, carbon fiber materials and unprotected electronics. So in order to extend the lifespan of a spacecraft, one first needs to counter the corrosion caused by atomic oxygen. This can be done by using proper materials for making the spacecrafts components and by avoiding the exposure of sensitive electronics to space.
Captain Corrosion OÜ proudly presents a three part video series about corrosion in space. These science videos were made in collaboration with the department of materials science, University Tartu and were partially funded by the “Center of Excellence” (Project TK141). Corrosion in space is actually quite relevant right now as there are more spacecrafts in the orbit than ever before and their number keeps increasing. An average spy satellite, disguised as a weather satellite, costs about 400 million euros and their lifespan is somewhat limited due to various reasons like human errors, software/hardware failure and degradation of specific spacecraft parts due to the hostile environment of space (corrosion!). This “corrosion” of materials in space however can be quite complicated as there are multiple factors that contribute to the process. In our video series we discuss some of the most important factors. The general idea of this series is to provide additional information for companies that make spacecraft component so they can better plan their devices to last as long as possible in space.
Part 1 – How Does Atomic Oxygen Cause Corrosion in Space?
Part 2 – How do Charged Particles Cause Corrosion in Space?
Part 3 – How does Radiation Cause Corrosion in Space?
Silver nanorods / nanowires with well defined length (up to tens micrometers) and diameter (around 10 nanometers) can easily be prepared by template synthesis method.
First a template is created by anodizing aluminum. In this process a porous oxide layer is created on top of the metal. The distribution, diameter and length of the pores depends on the anodizing solution and electrical parameters.
In the next step the pores are filled with silver by electrochemical deposition. The growth starts at the bottom of the pores where the pores are connected to the conductive metal. Eventually the whole pore is filled with silver and the deposition is stopped.
In order to get the silver nanorods out of the aluminum oxide matrix, the oxide needs to be etched away. The oxide matrix is removed almost instantly when dipping the substrate into an alkaline solution. As a result the silver nanorods escape into the solution. The amount, diameter and length of the nanorods depends on the oxide template that was used in the preparation process.
Large quantities of silver nanorods can be prepared in that way since in the pores in the oxide matrix are very close to each other which means that after deposition the substrate surface mostly consists of silver in the pores. Also in the etching process only the thin oxide layer is removed from the substrate to extract the nanowires and this means one can easily tune the amount of silver nanorods in a solution by the amount of substrates dipped into the same solution. For example for preparing a solution with a small concentration of silver nanowires only one sample is dipped into the solution. All the nanorods on that sample then go into the solution. By dipping the next sample into the same solution all of the nanowires on the second sample also go into the solution and the concentration is doubled. This process can be repeated as long as aluminium oxide etching is still possible. Note that the sample needs to be removed from the solution once its oxide layer is removed (this may take only a few seconds).
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