#
# arev:/usr/local/unicat/unireq/beamreq/req00089.txt
# UNICAT Member Beam Time Request  #89

# created Mon Nov 22 17:21:03 CST 1999
#

collaboration:
	No

days:
	6

description:
	In our last run at 33ID, we successfully measured coherent X-ray diffraction (CXD) patterns from microscopic grains of gold in a thin film.  Grains as small as 0.1 microns gave sufficient signal to measure with a 30 min CCD exposure.  We attempted heating experiments of the gold-on-glass films intending to see the onset of crystallization of the films.  However these attempts were defeated by the softening temperature of the glass substrates at around 800C.  
	Since then we have been working on the image reconstruction algorithms for small compact objects.  These work well for calculated CXD patterns, but not yet for the real data.  A symptom of the problem is that the experimental diffraction patterns were not centrosymetric, so probably indicating that the imaged grains were highly strained or contained grain boundaries.  It is necessary to investigate better controlled samples.
	We have now ordered gold-on-quartz samples that should withstand heating to the 1000C range necessary to grow well-formed microcrystals, according to the published protocols of Heyraud and Metois.  We have designed a heater configuration that will minimize the evaporation of the films over the multi-hour time intervals needed to achieve the ECS.
	The new samples will be ready in January for measurement at 33ID, using the same CCD setup we have used previously.

equipment+required:
	Huber diffractometer
	Furnace in chem lab

experiment:
	Equilibrium crystal shapes of gold microparticles

hazards:
	The toxic and hazardous chemicals need in the last run will not be used this time.
	The 1000C temperatures needed to anneal the films are within the safe operating rance of the UNICAT furnace.
	No open flame permit will be needed this time.

name:
	Ian Robinson

new+request:
	on

nonmembers:
	

station:
	33ID-D

unacceptable+dates:
	Before Jan 24.
	Feb 13-18.
	DESIRABLE dates: March 13-19 (spring break)



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