In your opinion, what are the best ways to mitigate damageor overcome the challenge? There are some data sparse scanning data collection protocols in 4D-STEM and ptychography, that is said to be more dose efficient. It would be nice to see a video on stuff like this (if I'm ignorant of past videos, excuse the comment!) Maybe you could comment on optimising beam conditions for different samples. I suppose, each sample will require some attention, but what's the best place to start for say inorganic and organic, that would give good signal to noise while extending the sample's life? Thanks for the video! Looking forward to more
Thanks for your support. Aside from reducing your dose rate, the other approach to mitigate S/TEM beam damage is to simply drop the voltage down. This can often be a rather dramatic improvement, but it of course comes at the cost of reduced resolution (though maybe not a lot if you have Cs correction) and the hassle of having to reconfigure your S/TEM to operate at a different voltage (which is much more of a hassle compared to doing voltage changes on a SEM, for instance). As I mentioned in the video, there is a big push now for "direct detection" camera technology, which does a great job of collecting high conventional TEM images at very low doses, so there is also the instrumentation approach (if you have the money to spend on such a camera). There are also some STEM imaging approaches that are supposedly good for low dose applications, like DPC imaging (which really deserves its own video). As far as what to do for a given sample that you may have no experience with, you're doing a lot of "on the fly" adjustments. I like to start around 1.0 - 1.5 nA of beam current for TEM imaging of inorganic materials and then adjust from there depending on how the material behaves, but I also don't have a fancy "direct detection" camera to play with, either. Much of the time, you have to simply acknowledge that you are going to modify/damage the sample when you image it and you have to work quickly to get the best images you can before the sample is damaged beyond the point of being useful, but this is obviously a subjective judgement call on the part of the S/TEM operator. As you can see, there are definitely no straightforward or easy answers here!
In your opinion, what are the best ways to mitigate damageor overcome the challenge? There are some data sparse scanning data collection protocols in 4D-STEM and ptychography, that is said to be more dose efficient. It would be nice to see a video on stuff like this (if I'm ignorant of past videos, excuse the comment!)
Maybe you could comment on optimising beam conditions for different samples. I suppose, each sample will require some attention, but what's the best place to start for say inorganic and organic, that would give good signal to noise while extending the sample's life?
Thanks for the video! Looking forward to more
Thanks for your support. Aside from reducing your dose rate, the other approach to mitigate S/TEM beam damage is to simply drop the voltage down. This can often be a rather dramatic improvement, but it of course comes at the cost of reduced resolution (though maybe not a lot if you have Cs correction) and the hassle of having to reconfigure your S/TEM to operate at a different voltage (which is much more of a hassle compared to doing voltage changes on a SEM, for instance). As I mentioned in the video, there is a big push now for "direct detection" camera technology, which does a great job of collecting high conventional TEM images at very low doses, so there is also the instrumentation approach (if you have the money to spend on such a camera). There are also some STEM imaging approaches that are supposedly good for low dose applications, like DPC imaging (which really deserves its own video). As far as what to do for a given sample that you may have no experience with, you're doing a lot of "on the fly" adjustments. I like to start around 1.0 - 1.5 nA of beam current for TEM imaging of inorganic materials and then adjust from there depending on how the material behaves, but I also don't have a fancy "direct detection" camera to play with, either. Much of the time, you have to simply acknowledge that you are going to modify/damage the sample when you image it and you have to work quickly to get the best images you can before the sample is damaged beyond the point of being useful, but this is obviously a subjective judgement call on the part of the S/TEM operator. As you can see, there are definitely no straightforward or easy answers here!