#
# arev:/usr/local/unicat/unireq/beamreq/req00024.txt
# UNICAT Member Beam Time Request  #24

# created Thu Jul 30 10:21:34 CDT 1998
#

days:
	9

description:
	1. TDS patterns of aluminum. Earlier results show rings from surface oxide and are unusable. New data are needed for freshly cleaned aluminum surfaces.
	2. In-plane diffraction intensities of Si(111)-(7x7) + 200 Angstrom or monolayer C60. The intensities of the (7x7) spots will be measured as a function of annealing temperature. This experiment will require the surface diffraction chamber. Presumably the pattern will become (1x1) at sufficiently high annealing temperatures. Rod scans are needed for this (1x1) surface to determine the structure, and in particular, the locations of the adatoms (presumably moved from the T4 site to the H3 site based on our latest model). If this experiment is successful, we will try Si(100).
	3. Anomalous scattering for submonolayers of Ge on Si(100) an Si(111). The purpose is to determine the atomic structure. For example, one question is the distribution of Ge in different atomic layers and sites.
	4. Anomalous scattering for the various reconstructions of Au, Ag, Bi, or other heavy adsorbates on Si(111). 
	
	If a displex (or sample cooling) is available:
	
	5. TDS patterns for superconductors, ferroelectrics, and other oxides that undergo phase transitions.
	6. Phonon dispersion curves and CDW phase transitions for TiSe2 and other CDW materials. This will require mounting the displex on a diffractometer. Temperature control of the sample is required.
	7. Phonon dispersion curves for Si, Ge, Al, LiF, and other materials by temperature dependent TDS measurements along high symmetry directions.  
	
	This is an ongoing project. More experiments are listed than what can possibly be done in the available time. Most likely, we will focus on experiments 1 and 2 listed above in this run.
	

equipment+required:
	Surface diffraction chamber. Transmission diffraction system. CCD or image plates. Displex (if available).

experiment:
	Surfaces, interfaces, phonons, superconductivity, CDW, and phase transitions

hazards:
	No special procedures needed. All samples are in solid form and are stable in air. Do not ingest or inhale.

name:
	Tai C. Chiang

nonmembers:
	

station:
	33ID-D

unacceptable+dates:
	



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