#
# arev:/usr/local/unicat/unireq/beamreq/req00029.txt
# UNICAT Member Beam Time Request  #29

# created Thu Oct 15 09:50:48 CDT 1998
#

days:
	6

description:
	Our recent least-squares analysis shows that TDS patterns can be used to deduced phonon dispersion curves. However, there is some uncertainty caused by an unknown intensity scaling factor (which translates into a frequency dependent, but k-independent scaling factor for the dispersion curves). This problem can be remedied by taking TDS data at several different temperatures. We will perform such measurements for Si, Al, LiF, and Ge. For Si (as our primary test case), we intend to take data at many different temperatures. Maximum temperature used would be limited to about 400 C. Heating will be done by direct current heating of the sample, by indirect heating via the mounting wires, or by placing the sample on a hot stage (if available). Temperature measurements need to be quite accurate and will be made by using thermocouples attached directly to the sample near the beam spot (and behind the beam stop).  

equipment+required:
	Image plate system. Hot stage or oven if available.

experiment:
	Phonon scattering patterns

hazards:
	No special procedures needed. All samples are in solid form and are stable in air. Mild heating in air or vacuum presents no special problems either in air, He atmosphere, and vacuum. Do not ingest or inhale.

name:
	T. C. Chiang

nonmembers:
	

station:
	33ID-D

unacceptable+dates:
	



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