909 research outputs found
Polymerisable octahedral rhenium cluster complexes as precursors for photo/electroluminescent polymers
New polymerisable photoluminescent octahedral rhenium cluster complexes trans-[{Re₆Q₈}(TBP)₄VB)₂] (Q = S or Se; TBP – p-tert-butylpyridine; VB – vinyl benzoate) have been synthesised, characterised and used to construct rhe-nium cluster-organic polymer hybrid materials. These novel polymer systems are solution-processable and the rhenium clusters retain their photoluminescent properties within the polymer environment. Notably, when the rhenium cluster complexes are incorporated into the matrix of the electroluminescent polymer poly(N-vinylcarbazole), the resultant cluster polymer hybrid combined properties of both components and was used successfully in the construc-tion of a polymer light emitting diode (PLED). These prototype devices are the first PLEDs to incorporate octahedral rhenium clusters and provide the first direct evidence of the electroluminescent properties of rhenium clusters and indeed, to the best of our knowledge, of any member of the family of 24-electron hexanuclear cluster complexes of molybdenum, tungsten or rhenium
Formulation of Supersymmetry on a Lattice as a Representation of a Deformed Superalgebra
The lattice superalgebra of the link approach is shown to satisfy a Hopf
algebraic supersymmetry where the difference operator is introduced as a
momentum operator. The breakdown of the Leibniz rule for the lattice difference
operator is accommodated as a coproduct operation of (quasi)triangular Hopf
algebra and the associated field theory is consistently defined as a braided
quantum field theory. Algebraic formulation of path integral is perturbatively
defined and Ward-Takahashi identity can be derived on the lattice. The claimed
inconsistency of the link approach leading to the ordering ambiguity for a
product of fields is solved by introducing an almost trivial braiding structure
corresponding to the triangular structure of the Hopf algebraic superalgebra.
This could be seen as a generalization of spin and statistics relation on the
lattice. From the consistency of this braiding structure of fields a grading
nature for the momentum operator is required.Comment: 45 page
Thermodynamic properties of ferromagnetic mixed-spin chain systems
Using a combination of high-temperature series expansion, exact
diagonalization and quantum Monte Carlo, we perform a complementary analysis of
the thermodynamic properties of quasi-one-dimensional mixed-spin systems with
alternating magnetic moments. In addition to explicit series expansions for
small spin quantum numbers, we present an expansion that allows a direct
evaluation of the series coefficients as a function of spin quantum numbers.
Due to the presence of excitations of both acoustic and optical nature, the
specific heat of a mixed-spin chain displays a double-peak-like structure,
which is more pronounced for ferromagnetic than for antiferromagnetic
intra-chain exchange. We link these results to an analytically solvable
half-classical limit. Finally, we extend our series expansion to incorporate
the single-ion anisotropies relevant for the molecular mixed-spin ferromagnetic
chain material MnNi(NO)(ethylenediamine), with alternating
spins of magnitude 5/2 and 1. Including a weak inter-chain coupling, we show
that the observed susceptibility allows for an excellent fit, and the
extraction of microscopic exchange parameters.Comment: 8 pages including 7 figures, submitted to Phys. Rev. B; series
extended to 29th. QMC adde
Integrated optimal structural and vibration control design
An integrated design procedure which is composed of structural design, control design, and actuator locations design is proposed in this paper. First, a composite objective function, formed by a structural and a control objective, is optimized in steady state through the homogenization design method. Then an independent modal space control algorithm (IMSC) is performed on this optimal structure to reduce the dynamic response. Finally, to minimize the control force while still obtaining the same modal response for the controlled modes, the optimal choice for actuator locations is discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46073/1/158_2005_Article_BF01197358.pd
Dusty ERO Search behind Two Massive Clusters
We performed deep K'-band imaging observations of 2 massive clusters, MS
0451.6-0305 at z = 0.55 and MS 0440.5+0204 at z = 0.19, for searching
counterparts of the faint sub-mm sources behind these clusters, which would
provide one of the deepest extremely red object(ERO) samples. Comparing our
near-infrared images with optical images taken by the Hubble Space Telescope
and by the Subaru Telescope, we identified 13 EROs in these fields. The sky
distributions of EROs are consistent with the previous results, that there is a
sign of strong clustering among detected EROs. Also, the surface density with
corrected lensing amplification factors in both clusters are in good agreement
with that derived from previous surveys. We found 7 EROs and 3 additional very
red objects in a small area (\sim 0.6 arcmin^2) of the MS 0451.6-0305 field
around an extended SCUBA source. Many of their optical and near-infrared colors
are consistent with dusty star-forming galaxies at high redshifts(z \sim
1.0-4.0), and they may be constituting a cluster of dusty starburst galaxies
and/or lensed star-forming galaxies at high redshift. Their red J-K' colors and
faint optical magnitudes suggest they are relatively old massive stellar
systems with ages(>300 Mega years) suffering from dust obscuration. We also
found a surface-density enhancement of EROs around the SCUBA source in the MS
0440.5+0204 field.Comment: 19 pages, 11 figures, Latex(using pasj00.cls). To be published in
PASJ vol 55, No. 4(Aug 2003
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