#
# top.uni.aps.anl.gov:/home/www/beamtime-requests/req00199.txt
# UNICAT Member Beam Time Request  #199

# created Fri Sep 28 10:45:36 CDT 2001
#
beamline:
	33ID

collaboration:
	No

collaborator+Hawoong:
	on

contact:
	t-chiang@uiuc.edu

days:
	2x3

description:
	Low temperature growth of thin Pb films on a clean Si(111)-(7x7) 
	surface creates self-organized 2 dimensional Pb islands whose
	 physical properties are thought to be dominated by quantum size
	 effects (QSE).  Recent STM studies have shown both a non -uniform 
	distribution of island height  ('preferred' or 'magical' island 
	heights), but also a remarkable oscillatory relaxation of layer
	 thicknesses - that is, regular deviations of island height from the 
	ideal height depending on thickness. 
	
	 To examine this effect, we propose a low temperature deposition 
	using the surface x-ray diffraction chamber in 33-ID E.  By collecting
	 the reflectivity and other crystal truncation rods of the Pb/Si(111)
	 system over a wide range in reciprocal space, we can extract the
	 nanoscale properties by fitting with a simple model that predicts
	 both population and relaxation of island heights on the surface.

equipment+required:
	

experiment:
	CTR measurement of oscillatory layer relaxation and preferred island height of Pb islands on Si(111)

foreign+nationals:
	Ma Zhong Quam

hazards:
	All samples are stable in air.  Usual cryogenic procedures for the 
	liquid N2 cooling in E hutch.

minimumdays:
	2x2

name:
	T.-C. Chiang

new+request:
	on

nonmembers:
	

unacceptable+dates:
	Nov 21-25


#REMOTE_HOST: chiangpc9.mrl.uiuc.edu
#REMOTE_ADDR: 130.126.102.93
#CONTENT_LENGTH: 1494
#HTTP_REFERER: http://www.uni.aps.anl.gov/unireq.htm
#HTTP_USER_AGENT: Mozilla/4.61 [en] (Win95; I)