Busy, busy
16/07/07 15:18 Filed in: Personal | Work Experiments
I've been a bit busy with things at the lab since we returned from our road trip last month. Many things have been unattended, and while I've actually written a few entries for the blog, they've never actually been posted. So kind readers (both of you), please excuse a few back dated posts.
We've been trying to wrap up our experiments with gold surfaces, at least to the point of having a good story worth writing. It's there, we just need a little extra work to have it all tied together nicely. There's usually some question of where to draw the line and write up your results. It would always be better to have and know more about what you're studying, but it also would never get published. The reverse of writing up every little step of progress is also to be avoided. In the words of Pliny the Elder, "...do what is worth being written, and write what is worth being read." (or something to that affect).
So we have decided on exactly what we need to put in our current paper and are attempting just such an experiment. The really exciting thing is that we've figured out a way to do it in our own lab! We have a rotating anode x-ray source set up with a full 4-circle diffractometer. Normally this is used to test things out before running at the synchrotron and provides us a nice way to characterize our sample quality ahead of time. However despite this being a very bright rotating anode source, it is still dismally dim compared to the synchrotron (ballpark, let's say a million times less photons). It also is essentially only capable of making a handful of different photon energies and changing between the energies requires a few days of effort.
But, let's say you already know almost everything you need to know. AND you've figured out exactly what you want to study, knowing exactly where you should find it. At the beamline this could be done with a scan that takes... let's say a minute. While synchrotron time is expensive, rare, and better used for other things, we can run our own dim x-ray source as long as we wish. So, that 1 minute stretches to an hour, which stretches to days, and ultimately let's say a week. That puts us at a factor of 1/10 the signal we could get during one of our beamline experiments and is entirely within acceptable limits!
We tested it this weekend and were successful at seeing the signal on a test sample! So at this point we need to get a good sample in the our beam. I prepared a sample all weekend and then tragedy struck this morning. While making the final adjustments before putting the sample in the experiment, I shattered the quartz and dropped the sample. Gold single crystals have a consistency very similar to butter. The fall from a few feet was enough to obliterate my precious (golum!). So, sadly, I'm preparing a new sample. Hopefully we can try tomorrow to start the experiment here.
Once we've done this, we're fairly confident that we can write up our results well enough. We've also been doing some very different experiments that confirm what we've already seen. It's certainly nice to have the extra proof, we're hoping to extend this in a new direction not previously possible. The new experiments involve a great deal of vacuum work. Instead of x-ray diffraction and scanning microscopy, I've been trying electron diffraction and photo-electron spectroscopy! Both are quite nice and deserve a bit of explanation, though I'm afraid that will have to wait a bit. However, you can see an example of the electron diffraction in the titlebar-mosaic above. It's the first picture on the far left.
We've been trying to wrap up our experiments with gold surfaces, at least to the point of having a good story worth writing. It's there, we just need a little extra work to have it all tied together nicely. There's usually some question of where to draw the line and write up your results. It would always be better to have and know more about what you're studying, but it also would never get published. The reverse of writing up every little step of progress is also to be avoided. In the words of Pliny the Elder, "...do what is worth being written, and write what is worth being read." (or something to that affect).
So we have decided on exactly what we need to put in our current paper and are attempting just such an experiment. The really exciting thing is that we've figured out a way to do it in our own lab! We have a rotating anode x-ray source set up with a full 4-circle diffractometer. Normally this is used to test things out before running at the synchrotron and provides us a nice way to characterize our sample quality ahead of time. However despite this being a very bright rotating anode source, it is still dismally dim compared to the synchrotron (ballpark, let's say a million times less photons). It also is essentially only capable of making a handful of different photon energies and changing between the energies requires a few days of effort.
But, let's say you already know almost everything you need to know. AND you've figured out exactly what you want to study, knowing exactly where you should find it. At the beamline this could be done with a scan that takes... let's say a minute. While synchrotron time is expensive, rare, and better used for other things, we can run our own dim x-ray source as long as we wish. So, that 1 minute stretches to an hour, which stretches to days, and ultimately let's say a week. That puts us at a factor of 1/10 the signal we could get during one of our beamline experiments and is entirely within acceptable limits!
We tested it this weekend and were successful at seeing the signal on a test sample! So at this point we need to get a good sample in the our beam. I prepared a sample all weekend and then tragedy struck this morning. While making the final adjustments before putting the sample in the experiment, I shattered the quartz and dropped the sample. Gold single crystals have a consistency very similar to butter. The fall from a few feet was enough to obliterate my precious (golum!). So, sadly, I'm preparing a new sample. Hopefully we can try tomorrow to start the experiment here.
Once we've done this, we're fairly confident that we can write up our results well enough. We've also been doing some very different experiments that confirm what we've already seen. It's certainly nice to have the extra proof, we're hoping to extend this in a new direction not previously possible. The new experiments involve a great deal of vacuum work. Instead of x-ray diffraction and scanning microscopy, I've been trying electron diffraction and photo-electron spectroscopy! Both are quite nice and deserve a bit of explanation, though I'm afraid that will have to wait a bit. However, you can see an example of the electron diffraction in the titlebar-mosaic above. It's the first picture on the far left.