22 Apr 2014

An update on X-ray

Submitted by Chip Nataro, Lafayette College

I've previously posted on a wonderful lab that can be found here on VIPEr. The lab describes the synthesis of zinc oxide nanoparticles which are then characterized by powder XRD. One of the wonderful aspects of VIPEr is the interaction of the community. And for me, to be able to try out this lab, and then get insight and feedback from the author was incredibly useful.

As some background, I teach a unit on solids in my 'sophomore' course. When I first started teaching it, I had one lab in which we used model kits to visualize different structures. After the first year, I learned that we had a powder XRD instrument, but it was in the geology department. I felt that I needed to add another lab relevant to this particular unit and I thought it was important that students get some exposure to XRD. So, I contacted my colleague in geology and fortunately he was very willing to help me out. The following year I included a lab where we made a sample and took it over to geology for testing. The combination of a solution phase organometallic chemist and a geologist did not lead to the best results. Sure, we got a pattern, but I was not very comfortable with the results. Over the years I have tried a number of different experiments, all with similar results. That is until I discovered this zinc oxide nanoparticle lab. My class performed the synthesis and we got X-ray data, but I had no clue if it was good data. So, I was able to contact the author, Catherine Oertel, and she got back to me within a few hours. I learned that our data looked normal and that it could be used for determining the size of the nanoparticles. This was in complete contrast to my colleague in geology who thought that the data was very poor. If I only had his opinion to work with I probably would have moved on to yet another lab.

So, how has this had a lasting impact? Well, I have used the lab for 4 years now. And I still really like it. My colleague in geology recently acquired a new instrument, so we are able to get reasonable data in about 10 minutes. That means that the students actually get an opportunity to obtain their own data and compare it to known standards. Our previous instrument was quite old and did not allow for data collection to be completed in a laboratory period. Now that the students are learning more about the instrument, I feel like I should cover a bit more of the theory in class. This year I introduced them to Miller Indices for the first time. Based on the test results (from a Star Trek themed exam that Maggie Geselbracht and I need to work into an LO), students seems to have a very good comprehension of the material. Is the solid state section of my course perfect? Of course not. But it is a heck of a lot better than it was at first. And that is all due to a learning object from VIPEr. Thanks Catherine.