Confinement and Fluorescence of Aromatic Molecules in Microporous Amorphous Superlattices

1986 ◽  
Vol 76 ◽  
Author(s):  
C. B. Roxlo ◽  
P. Mitra ◽  
H. W. Deckman ◽  
B. Abeles ◽  
P. P. Wong
Keyword(s):  
Time Dependence ◽  
Pore Size ◽  
Fluorescent Probe ◽  
Ground State ◽  
Minimum Size ◽  
Aggregate Formation ◽  
Excitation Spectra ◽  
Aromatic Molecules ◽  
Molecular Confinement ◽  
Microcrystalline Material

ABSTRACTWe have investigated molecular confinement in materials with nanometer sized pores, fabricated from amorphous superlattices of a-Si:H/a-SiOx:H, using 1,10-bis(1-pyrenyl)decane as a fluorescent probe. In large (46 Å) pores, the emission and excitation spectra and their time dependence are similar to microcrystalline material, showing the presence of molecules aggregated in the ground state. This dimer emission decreases sharply as the pore size is decreased, showing that the minimum size for aggregate formation is about 20 Å.

π-Stacking in Conjugated Polymers and Oligomers: A Structural and Spectroscopic Study

1998 ◽  
Vol 548 ◽  
Author(s):  
M. David Curtis ◽  
Wendy Blanda ◽  
Jeffrey K. Politis ◽  
Anthony H. Francis ◽  
Jihoon Lee ◽  
...  
Keyword(s):  
Fine Structure ◽  
Conjugated Polymers ◽  
Spectroscopic Study ◽  
Ground State ◽  
Solution Phase ◽  
Excitation Spectra ◽  
Aromatic Molecules ◽  
State Aggregation ◽  
Π Stacking ◽  
Pattern Characteristic

ABSTRACTRegioregular, alkyl-substituted poly(heteroaromatics) tend to crystallize in π-stacked structures as opposed to the herringbone pattern characteristic of non-substituted, planar aromatic molecules, e.g. sexithiophene. π-Stacking, favored by the crystallization of the sidechains, induces planarity in the conjugated backbone. The increased planarity causes a large (50-100 nm) shift in λmax (abs.) compared to the solution phase in which the backbone is twisted out of coplanarity, π-Stacking is a form of ground state aggregation that causes “fine structure” on the absorption peak. Excitation into the aggregate states rapidly leads to the formation of excimers as shown by the excitation spectra. In -stacked polymers, photoluminescence is almost entirely from the excimer states.

scholarly journals Excitation spectra and ground state properties of the layered spin-12frustrated antiferromagnetsCs2CuCl4andCs2CuBr4

2007 ◽  
Vol 75 (17) ◽  
Author(s):  
John O. Fjærestad ◽  
Weihong Zheng ◽  
Rajiv R. P. Singh ◽  
Ross H. McKenzie ◽  
Radu Coldea
Keyword(s):  
Ground State ◽  
Excitation Spectra ◽  
Ground State Properties ◽  
Layered Spin

Synthesis and Characterization of Novel Platinum Acetylide Oligomers

2003 ◽  
Vol 771 ◽  
Author(s):  
Thomas M. Cooper ◽  
Benjamin C. Hall ◽  
Daniel G. McLean ◽  
Joy E. Rogers ◽  
Aaron R. Burke ◽  
...  
Keyword(s):  
Absorption Spectra ◽  
Ground State ◽  
Near Infrared ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Laser Flash ◽  
Structure Property ◽  
Ground State Absorption ◽  
Excitation Spectra ◽  
C Nmr

AbstractAs part of an effort to develop a spectroscopic structure-property relationship in platinum acetylide oligomers, we have prepared a series of bidentate Pt(PBu3)2L2 compounds. The ligand was the series o-syd-C6H4-CΞC-(C6H4-CΞC)n-H, n = 0,1,2. The terminal oligomer unit consisted of a sydnone group ortho to the acetylene carbon. The compounds were characterized by various methods, including 13C-NMR, ground state absorption, fluorescence, phosphorescence and laser flash photolysis. The acetylenic 13C-NMR resonances showed sydnone influences that decreased with increasing number of monomer units. The ground state absorption spectra were slightly red shifted from those of the baseline oligomers not having a sydnone group. The low temperature emission and excitation spectra showed complex dependence on excitation and emission wavelengths, suggesting the chromphores resided in a distribution of solvent environments and conformations. Finally, broad triplet state absorption spectra were observed, with absorption throughout the visible and near infrared regions.

Resonant Photoluminescence Excitation in GaAs Grown Directly on Si

1988 ◽  
Vol 116 ◽  
Author(s):  
S. Zemon ◽  
C. Jagannath ◽  
S. K. Shastry ◽  
W. J. Miniscalco ◽  
G. Lambert
Keyword(s):  
Ground State ◽  
Heavy Hole ◽  
Laser Excitation ◽  
Free Exciton ◽  
Light Hole ◽  
The Other ◽  
Organometallic Vapor Phase Epitaxy ◽  
Photoluminescence Excitation ◽  
Excitation Spectra ◽  
Excitation Line

AbstractWe describe new results observed during resonant excitation in the excitonic region of GaAs grown directly on Si by organometallic vapor phase epitaxy. Two resolved features were found in the light hole photoluminescence (PL) region, one identified with a free exciton process and the other with donor-related transitions. Features which track the laser excitation line were observed and identified with a process in which a donor is excited from the n=l ground state to an n=2 excited state. The PL excitation spectra associated with these features have spectral widths as narrow as 1.5 meV. PL spectral widths of ~3 meV have been attained for the heavy hole exciton band, representing the narrowest value obtained for OMVPE material and an improvement of about 30% over our best previous results.

Thiophosgene monomer–dimer equilibria in perfluoroalkane solutions: spectroscopic and photophysical implications of self-association in the ground state

1993 ◽  
Vol 71 (10) ◽  
pp. 1548-1555 ◽  
Author(s):  
Andrzej Maciejewski ◽  
Marian Szymanski ◽  
Ronald P. Steer
Keyword(s):  
Absorption Spectrum ◽  
Oscillator Strength ◽  
Absorption Spectra ◽  
Strong Evidence ◽  
Ground State ◽  
Excitation Spectra ◽  
Direct Excitation ◽  
Self Association ◽  
Single Formula ◽  
Self Aggregation

The S2–S0 absorption, emission, and emission excitation spectra of thiophosgene in a perfluoroalkane solvent have been measured as a function of the analytical concentration, C, of the solute. Strong evidence of the formation of van der Waals dimers at 10−4 M < C < 10−1 M and of higher oligomers at C > 10−1 M has been found. Variations in the absorption spectra at C < 10−1 M have been analyzed successfully in terms of a single [Formula: see text] equilibrium, for which the value of K is (5.0 ± 0.4) × 102 M−1 at 295 K. The mole fractions of monomer and dimer have been calculated at each C, and have been used to construct the absorption spectrum of the dimer. Both the monomer and dimer have similar S0 → S1, and S0 → S2 absorption spectra, but the dimer has an oscillator strength that is about twice that of the monomer. The effects of self-aggregation on the S2–S0 emission and excitation spectra have been analyzed. Absorption by the dimer in the ultraviolet also leads to emission, but with a different quantum efficency compared with direct excitation of the monomer. The implications of these observations on the interpretation of the spectroscopy, photophysics, and photochemistry of thiophosgene in solution are assessed.

GROUND STATE AND LOW-EXCITED STATES OF A BOSE GAS IN A FINITE ANISOTROPIC TRAP

2008 ◽  
Vol 22 (28) ◽  
pp. 5003-5014 ◽  
Author(s):  
LIANGHUI WEN ◽  
YONG-LI MA
Keyword(s):  
Ground State ◽  
Collective Excitation ◽  
Three Dimensional ◽  
Finite Amplitude ◽  
Einstein Condensate ◽  
Harmonic Potential ◽  
Excitation Spectra ◽  
Basis Expansion ◽  
Ground State Wavefunction ◽  
Bose Einstein Condensate

The motivation in this paper is to simulate numerically some properties of an interacting Bose–Einstein condensate at zero temperature in an axial symmetry trapping potential with finite amplitude for modeling the practical experimental cases. By use of the basis expansion using three-dimensional harmonic oscillator eigenfunctions, we obtain the ground-state wavefunction and the collective excitation spectra of the system in both usual harmonic potential and different amplitudes of the finite potential. After comparing our results for the finite potential with the data derived from the harmonic potential, we conclude that the finite trap in the practical experiments decreases the entire excitation frequencies in the whole regimes. This decrease is consistent with our analytic prediction qualitatively and agrees well with the experimental data quantitatively.

Sign in / Sign up

Export Citation Format

Share Document