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Optical Diagnostics of Solution Crystal GrowthNon-contact optical techniques such as, optical heterodyne, ellipsometry and interferometry, for real time in-situ monitoring of solution crystal growth are demonstrated. Optical heterodyne technique has the capability of measuring the growth rate as small as 1A/sec. In a typical Michelson interferometer set up, the crystal is illuminated by a Zeeman laser with frequency omega(sub 1) and the reference beam with frequency omega(sub 2). As the crystal grows, the phase of the rf signal changes with respect to the reference beam and this phase change is related to the crystal growth rate. This technique is demonstrated with two examples: (1) by measuring the copper tip expansion/shrinkage rate and (2) by measuring the crystal growth rate of L-Arginine Phosphate (LAP). The first test shows that the expansion/shrinkage rate of copper tip was fast in the beginning, and gets slower as the expansion begins to stabilize with time. In crystal growth, the phase change due the crystal growth is measured using a phase meter and a strip chart recorder. Our experimental results indicate a varied growth rate from 69.4 to 92.6A per sec. The ellipsometer is used to study the crystal growth interface. From these measurements and a theoretical modeling of the interface, the various optical parameters can be deduced. Interferometry can also be used to measure the growth rate and concentration gradient in the vicinity of the crystal.
Document ID
19960052298
Document Type
Conference Paper
Authors
Kim, Yongkee
(Alabama A & M Univ. Normal, AL United States)
Reddy, B. R.
(Alabama A & M Univ. Normal, AL United States)
George, T. G.
(Alabama A & M Univ. Normal, AL United States)
Lal, R. B.
(Alabama A & M Univ. Normal, AL United States)
Date Acquired
August 17, 2013
Publication Date
July 1, 1996
Publication Information
Publication: HBCUs Research Conference Agenda and Abstracts
Subject Category
Solid-State Physics
Report/Patent Number
Paper-2
Accession Number
96N35495
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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