Improved Microscope Technology to Study Dynamic Material Processes
Researchers at Lawrence Livermore National Laboratory have perfected an electron microscope to study fast-evolving material processes and chemical reactions. By applying engineering, microscopy, and laser expertise to the decades-old technology of electron microscopy, the dynamic transmission electron microscope (DTEM) team has developed a technique that can capture images of phenomena that are both very small and very fast. DTEM uses a precisely timed laser pulse to achieve a short but intense electron beam for imaging. When synchronized with a dynamic event in the microscope's field of view, DTEM allows scientists to record and measure material changes in action. A new movie-mode capability uses up to nine laser pulses to sequentially capture fast and irreversible material changes at the nanometer scale.
Transcript
00:00:02 we were able to use the expertise here at Livermore in lasers opens this whole new broad realm of Sciences how does this process change when you make it go a billion times faster DM is a a rather interesting combination of lasers and an electron microscope we've used the d10 successfully to actually image the crystals as they
00:00:34 grow but now we use a laser to make it generate electrons in a pulsed fashion so we send a pulse of ultraviolet light up to a photoc cathode in the gun of of the microscope and that when it hits the photocathode it ejects electrons only for as long as those photons are hitting that photocathode and so the pulse duration of the electrons is exactly the pulse duration
00:01:06 of the laser and that can be made quite short and so we generate this intense pulse of electrons up at the gun and send it down through the column just like a normal electron microscope and it interacts with our specimen creates the image or defraction pattern and we collect it on a CCD camera what we want to study is the actual interface between the solid and
00:01:30 the liquid liquid phase as it solidifies you can't see um the details of the changes in the micr structure um in order to do that you need some Imaging method and so that's what the what the DM can do initially what we could do is look at the initial State the final State and have no idea was now the DM fills in all the gaps in between if you have just a single shot a single
00:01:52 picture it it it tells you it gives you information but it it really doesn't tell the whole story you really need to be able to follow the evolution of the specimen in these Dynamic events and that requires a movie it was it was great I I was and actually seeing the first the first image the first time when we saw just you know the grains growing in the sequential images it was
00:02:16 like wow I didn't I didn't realize like I knew this is the way it's supposed to operate but it's it's fantastic to see it operating like this it works