The aim of the following experiment is to study the dynamic processes of materials in liquids in real time with high spatial resolution using transmission electron microscopy. This is achieved by first micro fabricating a liquid cell from ultra thin silicon wafers. As a second step, inject 100 nanoliters of reaction solution into the reservoir of the cell using a syringe and Teflon nanotubes.
Then seal the liquid cell with a cover. Next, load the liquid cell into the TEM sample holder as a standard TEM sample and insert the sample holder into the microscope for in situ TEM experiments. This process shows the dynamic growth of nanoparticles in liquids such as the formation of platinum three iron compound nanowires using real-time imaging with sub nanometer resolution.
The main advantage of this self-contained liquid cell technique is that a thin liquid layer can be maintained in the viewing window long enough to allow an extended chemical reaction to occur. This method can illuminate key aspects of material science and physical chemistry, such as growth and transformation dynamics of materials in liquids. This method can provide insights into the nano crystal growth and assembly mechanisms.
It can also be used to image biological materials in their native environments. Generally, individuals new to this method will struggle because it requires a series of fabrication processes to make the liquid cells, and it's a challenge to handle the tiny liquid cells for the institute. TM experiments.
I have always been fascinated with how crystal grow and transform at the nanoscale, especially. There are a lot of mysteries of these processes happening in liquids. Our liquid cell method has opened an entire field of study on not only colloidal nano crystal growth, but also a variety of processes in liquids that require high spatial and temporal resolution.
Demonstrating this procedure will be two postdocs in my laboratory. Nu and Hong Microfabrication of liquid cells takes place in a clean room, begin microfabrication of the liquid cells using ultra thin silicon wafers. These wafers are 100 micrometer thick, four inch end type silicone wafers.
Deposit 20 nanometers of low stress silicon nitride films on both sides of the silicon wafer. Next fabricator viewing window in the center of the bottom chip. The top chip contains two reservoirs along with a viewing window deposit.
Indium spaces on the bottom chip using an optical microscope, align the viewing windows of the top and bottom chips and bond them together. First, weigh out 20 milligrams of platinum, two acetyl acetate, and 20 milligrams of IN two acetyl eight. The platinum and ion reaction solution is then prepared by combining the platinum and ion into one milliliter of Penta decade and Ola aiming in a seven to three volume to volume ratio.
Next, load the reaction solution into a syringe equipped with a Teflon nano tube. Then use the syringe to inject about 50 nanoliters of the reaction solution into the liquid reservoir. Taking care not to contaminate the electron transmission window, the reaction solution is drawn into the cell by capillary force and forms a liquid layer of about 100 nanometers between two silicon nitride viewing windows.
Continue injecting to fill the other reservoir with an additional 50 nanoliters of solution. Cover the liquid cell with a thin copper TEM grid using vacuum grease to create a tight seal. Begin imaging with the transmission electron microscope or TEM by loading the prepared liquid cell into the TEM sample holder.
Once positioned in the sample holder, insert the liquid cell into the TEM. Shown here is A-J-E-O-L 30 10 TEM operated at 300 kilovolts. With the sample in place, tune the microscope to a perfect high resolution TEM imaging condition using a beam current density of one to eight times 10 to the five amps per meter square.
This initiates nucleation and growth of the nanoparticles in the liquid layer commence real-time monitoring of the nanoparticle dynamics using virtual dub and gatan digital micrograph programs. Once exposed to the electron beam, the nucleation and growth of platinum three iron compound nanoparticles occur. Nanoparticles grow to four to five nanometers by either monomer attachment or coalescence between small nanoparticles.
In reaction over time, shape directed nanoparticle attachment occurs and nanowires are formed. In this case, the growth of platinum three iron compound nanowires was altered by surfactants. When an additional surfactant oleic acid is added to the reaction solution, it results in thinner and straighter nanowires than those in a solvent of just pento, decane and ole amine.
It is possible for shorter nanowires to combine and form longer ones Once attached, the wires tend to straighten out over time. While attempting this procedure is important to remember to seal the LI cell well before loading the sample into the microscope After its development. This technique paved the way for researchers in the field of material science and chemistry to explore crystal growth and materials transformation dynamics in liquids and the nanoscale.
Don't forget working with reactive solutions can be hazardous. Precautions should always be taken. Wear gloves, wear s safety glasses, and wear lab coat while performing your experiments and dispose of your materials properly.
