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The
research is aiming at the correlation between atomic structure and
observed optical properties.
New chiral
substances are synthesized as models for structure-feature studies,
for example from adding chiral ligands to isothyocyanates. These new
substances crystallize well and allow a multitude of variations of
their chemistry while being strongly structurally
related.
Similarly,
structural phase-transitions cause variations in structures which
are the cause of sometimes strong changes of the optical
properties.
New
optical measurement techniques are developed to collect data on
chiroptical properties like optical rotation, Faraday Effect,
circular dichroism, the electro-optic effect, and electrogyration.
Such new methods are:
-
1) the
'tilter - method' that allows to measure optical rotation in any
transparent crystal,
-
2) an
imaging polarized microscope which allows simultaneous precision
measurement of linear dichroism, retardation and extinction angles
of heterogeneous samples,
-
3) a
microscope which is designed to image circular extinction in
solids, U-pol
of
light which allow calculating electrogyration, the electro-optic
effect and the d-coefficients for frequency doubling, using the
atomic structure and empirical polarizability volumes for the
individual atoms.
Crystal
growth from aqueous or other solutions and their crystallographic
characterization (forms, structure, and basic physical properties)
assist the research. The aim is to provide large samples of
interesting chemical composition in the size-range of
cube-centimeters.
X-ray
structure determination and chemical analysis as part of the duties
for the Department of Chemistry in Seattle complement these
studies.
I devoted
some of my time to the development of software packages to aid the
teaching of physical crystallography. This resulted in one program
for the presentation of tensorial features in form of representation
surfaces (WinTensor for Win95/98/NT/2000/XP) and another program for
the presentation of crystal morphology as virtual reality models
(WinXMorph for Win95/98/NT/2000/XP).
1.
Periodic table
of Verdet constants of Ions. The Faraday
rotation of over 250 cubic crystals was studied and the first and so
far only comprehensive compilation (almost complete periodic table)
of specific Verdet constants of elements in different valence states
was derived, including temperature dependence.
2.
The first to
measure complete Verdet tensors in non-cubic crystals,
including triclinic symmetry.
3.
Algorithm to
invert numerically a sinusoidally varying signal with smoothly
changing amplitude.
4.
The tilter
method. A method was
developed to measure the optical rotation of birefringent solids ca.
1000 times faster than competing methods.
5.
The first (and
so far only) to measure optical rotation topographs in
birefringent solids.
6.
The
DES-model. A theory and
software was developed to calculate the electro-optic tensor, the
d-coefficients, and the electro-gyration tensors in crystals of any
symmetry from the x-ray structure and empirical polarizability
volumes of the atoms.
7.
Solving the over
100-years old problem of Pasteur's findings of optical
rotation in solutions versus crystals of Tartaric Acid.
8.
Developing an
imaging system to unfold images of birefringence, eigenrays
and transmittance.
9.
Solution to the
problem of ambiguity of birefringence
measurements.
10. Discovery of
anomalous azimuthal rotation in dyed crystals (AAR)
11. First
to measure circular dichroism images with a new device,
U-pol, (patent pending).
12. Discovery of AAR
related anomalous circular extinction in dyed crystals
(ACE-effect).
13. Development of a
system to unfold images of birefringence, eigen rays and
transmittance on a millisecond timescale.
14. Two
educational software packages, WinTensor to study tensorial
properties and WinXMorph to study crystal morphologies are
licensed through the University of
Washington
15. The
first to measure images of the electro-optic effect in birefringent
solids.
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