Sonoma State University
Fall 2001
Physics 384
John Dunning, Jr.

Experiments

1) Properties of X-rays following Chapter 1 of Cullity. X-ray absorption. Demonstration run of Si02 standard and retrieve appropriate PDF card. Introduction to X-ray diffraction and the PDF file. Laboratory Exercise: Obtaining PDF Cards. Problems 1,1, 1,8 mass absorption coefficients in appendix 8., 1.9 using the K absorption edge wavelength in appendix 7. Safety Handout.

2) X-ray safety discussion, Video on X-ray safety, X-ray Safety Quiz (if not already taken).. Diffractometer Measurement Chapter 6-1 to 6-4, 6-7, 6-9, 6-11. Continued outline of diffraction. Discussion of Computerized search/match. Demonstration analysis of a two component unknown. Ch. 9-1 9-3, 9.7 Laboratory Exercise: Getting More from Search/Match. Safety Quiz

3) Diffraction outline continued. Intensity of Diffracted Beams 4-1 to 4-3, The absorption factor and sample thickness considerations from chapter 4-9, 4-10 of Cullity. Angle offsets, Ch. 13-2. The distance in figure 13.2 should be d/sinq. Instrument experiment 1: Whiteners and clay in papers.

4) Specimen Preparation. First Project discussion. Each group will prepare, run and analyze two interesting samples using X-ray diffraction, visual observation with a microscope, and other appropriate aids short of X-ray fluorescence.

Option one: Compare Dark Green sand collected at a volcanic beach on the big island of Hawaii with sand from Lizard Island, a volcanic island in the Great Barrier reef. The green sample will benefit from some hand concentration of the darker grains.

Option two: Compare white sand of an unknown origin with sand collected at the main beach in Surfer's Paradise (Queensland).

Option three: An interesting crystalline material from British Columbia. A clay of unknown origin which may be Kaolinite. How well do the clay peaks agree with those found in one of the paper samples in experiment #1?

Option four: Two minerals. One is red and needs to be ground under the hood using gloves. The other has a darker texture. The red sample may help us understand the Gectel mine ores in the second project.

Option five: Two minerals. One is blue. The other has crystalline parts.

Option six: A fossil from Spain. A dark brown crystal of unknown origin.

Option seven: Two samples collected from a road side cut above and below a dam under construction on the Rio Guadalfeo south of Granada, Spain. What are the major minerals or groups of minerals present?

Some of the above are intended to be standards. One runs the pure compounds to establish experimentally the pattern. Sharing of data by placing it on the same Zip disc will enrich the course.

As appropriate: Is the macroscopic crystal structure you can see with the dissecting binocular microscope the same as the atom scale structure revealed by X-ray diffraction?

5) Discussions of first projects. Counting statistics, sample run time and minimum detectable signal to noise. Chapter 6-11. Problem 6.4. Instrument experiment 2: Separate the K_1 K_2 lines of copper using a large angle line of NaCl. Estimate the local magnetic field in copper.

6) 30 minute Quiz. Continue with first project. Possible guest lecture on polymers that are present in paper.

7) First Project Due. Second project introduction (2nd project talk in 3 weeks). Choices so far for the 2nd project:

a) Comparative analysis of two stamps from Spain. One from is 1862. The other is from 1969.

b) Comparative analysis of an interesting 4 cent brown U.S. stamp from before 1930 and a 1962 blue US stamp celebrating the space program.

c) Comparative analysis of a US $5 bill and an Australian $5 bill.

d) Comparative analysis of a 2001 US 34¢ stamp and Greek stamp dated 1912.

For the above. XRD should be done first. XRD may suggest that there are interesting higher Z elements present. X-ray fluorescence is used to substantiate the presence of these elements, and to reduce the choices presented by the diffraction analysis. Surprising differences may be detectable in the cellulose peaks, the whitener, and/or the inks. For this to work well, Kaolinite, when present, should be regarded as a known and used to internally calibrate the angles. Sample preparation includes having a flat specimen. If the "sharp peaks" are broader than 0.24° full width at half maximum as read from the peak ID report compact, the sample should be reflattended and rerun.

e) Compare two ore samples from the Gectel mine in Nevada. The red sample from the first project has some bearing here.

f) Analyze a sample of quarry rock. I have a big slab. Do the red streaks contain more iron? The second search/match example has some bearing here.

g) Prof. Rolfe Erickson of the SSU Geology Dept. has promised an interesting mineral.

8) Introduction to X-ray fluorescence. This time we will use EDX to determine the dominant elements present so that the chemical filters in Jade can be used to advantage. EDX of your samples will be used to support the XRD data.

9) Hints for better for oral reports. Introduction to the reciprocal lattice and crystal systems. Chapter 2-1 2-3, 2-6. Introduction to our pattern indexing software. Rietveld refinement of crystal structure.

10) Oral reports on the 2nd projects.

11) Oral reports on the 2nd project continued. Instrument experiment 3: Analyze two different thin films deposited on glass. One to be chosen from group one. The other is to be chosen from group two where the crystal structure is altered by the deposition process.

12) Synchrotron radiation introduction. The Advanced Light Source.

13) Protein crystallography field Trip to the Advanced Light Source in Berkeley. The availability of ALS people and access will determine the actual scheduling of this outing.

14) The Los Alamos neutron science center (LANSCE) has been upgraded, and an advanced neutron source at Oak Ridge is under construction. Discussion of neutron powder diffraction. Current Examples from Los Alamos (lecture only).

Course Outline
Please send comments, additions, corrections, and questions to
john.dunning@sonoma.edu
JRD
2001-09-06