Learning symmetry:

In a number of the characterization techniques to be presented, a background in beginning crystallography is required. This background should be given in MatSE 201. Make sure that you assimilate this material immediately and fully. A place to read about and study geometrical crystallography is:

http://www.ems.psu.edu/Metals/classes/metal434/

Diffraction versus fluorescence:

It is often difficult for the beginning student at first to sort out the difference between x-ray diffraction and x-ray fluorescence techniques. There is, in reality, no mystery to this distinction......the differences should be obvious when you understand the material. Make sure that, as you listen to the class discussions, you learn to separate these two techniques.

Diffractometer configuration:

You will be expected to know the configuration of the x-ray powder diffractometer in detail. This is the most basic instrument in diffraction studies. It is simple enough in geometry, but students often fail to get the right parts where they belong, and understand why. One way to help fix the diffractometer configuration in your mind is to visit one (304 Steidle) and study it at length; ask me or one of the graduate assistants to help if you are confused here. Many of you will, during this very semester and in your senior year, be required to work with an x-ray powder diffractometer in your labwork and in senior project work.

Request:

Please always use right-handed coordinate systems with a out, b to the right, and c up.

Pocket computers:

Pocket computers are appropriate. If you have one, you should consider writing short programs for various calculations.

Memorization:

If you find that, in reviewing for a 430 exam, you are trying to memorize the material, STOP! The need to memorize frequently means that understanding is lacking. Most students run into difficulty on 430 exams when they attempt to memorize the material rather than understand it in depth.

An example of memorization causing difficulty was a problem on an exam for a previous year which asked how to make the and 2 adjustments in the alignment of an x-ray diffractometer. Now, there was a page in the notes which discussed the various procedures for completely aligning a diffractometer as discussed in class. In the exam, most students carefully reproduced the drawings from this page, with practically no explanation, as the answer to the problem. In rote fashion, they included adjusting the tube, the take-off angle, and the distances in the diffractometer - and these had absolutely nothing to do with the question. Rather than memorizing this page, it would have been much better to carefully go through the procedures and understand what was being accomplished and why.

Can you get the answer to a homework problem out of a book?

Maybe.

However, a past homework problem presented the following difficulty. Students were asked to derive the normal equations for Cohen's least squares method for the determination of precise lattice parameters from x-ray diffraction data using a particular correction function. The mechanics of solving the problem involved substituting the correction function, in its correct form, into the main equation, taking three partial derivatives, and finishing with some rearranging of terms. For whatever reasons, most students chose to copy verbatim the answers presented in an extremely cursory treatment in Cullity. The problem was that Cullity used a different crystal system and a completely different correction function and did not detail how to take the derivatives, which, in reality, are very straightforward. Their homework answers were, simply, wrong, and woefully incomplete.

Then, during final exam study time, a student came in to ask: "Do we have to know how to take derivatives?"

The concept involved in this problem and the mathematical manipulations are well within the abilities and experience of junior and senior science and engineering students.

Don't believe everything you hear (or even see):

In a previous year, some material was presented at the beginning of a class which was totally false......it was a summary of the solution to a homework problem turned in by one of the students; the class dutifully copied down all of the material. At the beginning of the next class meeting, I gave a summary from another student's problem solution was presented which totally contradicted the previous discussion, but was also totally false, and it was also dutifully copied into notebooks. Several classes later, the solution was correctly presented, and again....into the notebooks. No one ever mentioned anything about this!

The point is that students should not simply transcribe material into their notebooks to use the week before exams. The class time should be used as a study time; concepts should become clear during the class. If this doesn't happen for you, then the appropriate procedure is to stand up and shout "whoa!!". Ask questions until things get resolved.

The following two selections are from James Adams' Conceptual Blockbusting.

A Questioning Attitude

One of the most important capabilities in a creative person is a questioning attitude. Everyone has a questioning attitude as a small child, because of the need to assimilate an incredible amount of information in a few years. The knowledge that you acquire between the ages of 0 and 6, for instance, enormously exceeds what has been consciously taught. A great amount of knowledge is gained through observation and questioning. Unfortunately, as we grow older many of us lose our questioning attitude. There are two principal reasons. The first is that we are discouraged from inquiry. After the child reaches a certain age, parents and others are often not as patient with questions (especially if they are busy and/or do not know the answer) that do not seem socially pertinent (Why can you see through glass? Why are leaves green?) and tend to discourage the questioner. Our educational institutions can barely convey the knowledge they are held responsible for (reading, writing, arithmetic, cultural lore). There is little time available for answering questions, so questions are effectively limited and discouraged. Many is the professor who begins his lecture with a plea for questions and then ends it with neither the time nor the encouraging attitude necessary to get them.

The second reason the child's "inquisitive" nature is socialized out of us (or at least diminished) has to do with "the great knowledge game." We learn as we grow older that it is good to be smart. Smartness is often associated with the amount of knowledge we possess. A question is an admission that we do not know or understand something. We therefore leave ourselves open to suspicion that we are not omniscient. Thus, we see the almost incredible ability of students to sit totally confused in a class in a university that costs thousands of dollars a year to attend and not ask questions. Thus, we find people at cocktail parties listening politely to conversations they do not understand, and people in highly technical fields accepting jargon they do not understand. One of my colleagues from my aerospace days used to delight in feeding nonsense jargon and erroneous arguments to people in other specialties. They would seldom question him in sufficient depth to find that he was faking. I have another friend who once successfully delivered a totally fraudulent hour-long lecture in aerospace medicine, of which he is totally ignorant, to an audience of university students. When his true credentials (none) were revealed to the students at the end of the lecture, they immediately voiced doubts that they had accumulated during the hour.

Incubation

You may work for days or weeks on a problem, complete it, and go on to other activities. Then at some seemingly random point in time, a better answer "appears". Since the original problem was probably completed in order to reach a deadline, this "better" answer often only serves to annoy you that you did not think of it sooner. This better answer came straight from the unconscious as a result of the "incubation" process it was going through. I have found in my own case that this "incubation" process works and is reliable. I have the confidence to think hard about a problem (charging up my unconscious) and then forget about it for a period of time. When I begin work on it again, new answers are usually present.

Many "symptoms" of incubation are common. There is a widespread belief among students that they do their best work just before deadlines. If, in fact, they work on the material when they receive it long enough to store the data in their unconscious, then incubation can occur, and a better solution may emerge at a later time. Students often claim to produce the right answer at the appropriate time. Students often claim to have come up with a winning idea the morning that it is due, after struggling futilely with the problem for days.

You must allow the unconscious to struggle with problems. Incubation is important in problem-solving. It is poor planning not to allow adequate time for incubation in the solution of an important problem. It is also important to be able to relax in the midst of problem-solving. Your overall compulsiveness is less fanatical when you are relaxed, and the mind is more likely to deal with seemingly "silly" combinations of thoughts. If you are never relaxed, your mind is usually on guard against non-serious activities, with resulting difficulties in the type of thinking necessary for fluent and flexible conceptualization.