197 research outputs found
Aggregation enhanced emission (AEE) in organic salt: A structure-property correlation based on single crystal studies
Salt formation has been shown as a simple strategy to induce aggregated induced emission or aggregated enhanced emission in primary ammonium salts derived from 9-anthracene carboxylic acid, 1-pyrene carboxylic acid, 3-coumarin carboxylic acid and histamine. All the salts displayed enhanced fluorescence in their solid state compared to that in their solution state. Single crystal structure of the salt of 9-anthracene carboxylic acid i.e., His-anthracene revealed that restricted intramolecular rotation of the fluorphoric moiety (anthracene) was responsible for such radiative pathway leading to enhanced emission
Shock Wave Mixing in Einstein and Dilaton Gravity
We consider possible mixing of electromagnetic and gravitational shock waves,
in the Planckian energy scattering of point particles in Minkowski space. By
boosting a Reissner-Nordstr\"om black hole solution to the velocity of light,
it is shown that no mixing of shock waves takes place for arbitrary finite
charge carried by the black hole. However, a similar boosting procedure for a
charged black hole solution in dilaton gravity yields some mixing : the wave
function of even a neutral test particle, acquires a small additional phase
factor depending on the dilatonic black hole charge. Possible implications for
poles in the amplitudes for the dilaton gravity case are discussed.Comment: 11 pages, revtex file, no figure
Quantum Black Hole Entropy
We derive an exact formula for the dimensionality of the Hilbert space of the
boundary states of SU(2) Chern-Simons theory, which, according to the recent
work of Ashtekar et al, leads to the Bekenstein-Hawking entropy of a four
dimensional Schwarzschild black hole. Our result stems from the relation
between the (boundary) Hilbert space of the Chern-Simons theory with the space
of conformal blocks of the Wess-Zumino model on the boundary 2-sphere.Comment: 7 pages, Revtex, some new references adde
Synthesis of 13C-labelled, bicyclic mimetics of natural enediynes
Using a versatile synthesis with 13CH3PPh3I and CH313CO2Et as 13C sources, the first examples of nine membered chromophores, which have been differentially labelled with 13C in their carbocyclic enediyne cores, are described
Aspects of Planckian scattering beyond the eikonal
Sherpa Romeo green journal. Permission to archive final published version.We discuss an approach to compute two-particle scattering amplitudes for spinless light
particles colliding at Planckian centre-of-mass energies, with increasing momentum transfer away
from the eikonal limit. The leading corrections to the eikonal amplitude, in our 'external metric'
approach, are shown to be vanishingly small in the limit of the source particle mass going to zero.
For massless charged particles, the electromagnetic and gravitational interactions decouple in the
eikonal limit, hut mix non-trivially for the leading order corrections.Ye
Electromagnetic charge-monopole versus gravitational scattering at Planckian energies
Sherpa Romeo green journal. Permission to archive final published version.The amplitude for the scattering of a point magnetic monopole and a point charge, at center-of-
mass energies much larger than the masses of the particles, and in the limit of low momentum
transfer, is shown to be proportional to the (integer-valued) monopole strength, assuming the Dirac
quantization condition for the monopole-charge system. It is demonstrated that, for small momentum
transfer, charge-monopole electromagnetic effects remain comparable to those due to the
gravitational interaction between the particles even at Planckian center-of-mass energies.Ye
Cosmic optical activity from an inhomogeneous Kalb-Ramond field
The effects of introducing a harmonic spatial inhomogeneity into the
Kalb-Ramond field, interacting with the Maxwell field according to a
`string-inspired' proposal made in earlier work are investigated. We examine in
particular the effects on the polarization of synchrotron radiation from
cosmologically distant (i.e. of redshift greater than 2) galaxies, as well as
the relation between the electric and magnetic components of the radiation
field. The rotation of the polarization plane of linearly polarized radiation
is seen to acquire an additional contribution proportional to the square of the
frequency of the dual Kalb-Ramond axion wave, assuming that it is far smaller
compared to the frequency of the radiation field.Comment: 9 pages, Revtex, no figure
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