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Joint Experimental (joint + experimental)

Distribution by Scientific Domains
Chemistry80%

Selected Abstracts

Modification of the Surface Properties of Indium Tin Oxide with Benzylphosphonic Acids: A Joint Experimental and Theoretical Study

ADVANCED MATERIALS, Issue 44 2009
Peter J. Hotchkiss
Benzylphosphonic acids with various fluorine substitutions are designed and synthesized. They are used to modify ITO such that the work function can be tuned over a range of 1.2 eV while keeping the surface energy relatively constant. The experimentally measured work function changes are also compared to and agree well with those estimated from DFT calculations. [source]

Exciton Migration in Conjugated Dendrimers: A Joint Experimental and Theoretical Study

CHEMPHYSCHEM, Issue 18 2009
Muhammet E. Köse Prof.
Abstract We report a joint experimental and theoretical investigation of exciton diffusion in phenyl-cored thiophene dendrimers. Experimental exciton diffusion lengths of the dendrimers vary between 8 and 17 nm, increasing with the size of the dendrimer. A theoretical methodology is developed to estimate exciton diffusion lengths for conjugated small molecules in a simulated amorphous film. The theoretical approach exploits Fermi's Golden Rule to estimate the energy transfer rates for a large ensemble of bimolecular complexes in random relative orientations. Utilization of Poisson's equation in the evaluation of the Coulomb integral leads to very efficient calculation of excitonic couplings between the donor and the acceptor chromophores. Electronic coupling calculations with delocalized transition densities revealed efficient coupling pathways in the bulk of the material, but do not result in strong couplings between the chromophores which are calculated for more localized transition densities. The molecular structures of dendrimers seem to be playing a significant role in the magnitude of electronic coupling between chromophores. Simulated diffusion lengths correlate well with the experimental data. The chemical structure of the chromophore, the shape of the transition densities and the exciton lifetime are found to be the most important factors in determining the size of the exciton diffusion length in amorphous films of conjugated materials. [source]

Crossed-Beam and Quantum Dynamics Studies of the Reaction Cl + CHD3

ISRAEL JOURNAL OF CHEMISTRY, Issue 1 2007
Gunnar Nyman
The ground-state reaction of Cl + CHD3 was studied with joint experimental and theoretical efforts. Experiments were performed under crossed-beam conditions using a time-sliced velocity imaging detection method. By taking the images over the energy range of chemical significance,from threshold to about 9 kcal/mol,the reactive excitation functions as well as the dependence of product angular distributions and of the energy disposal on initial collision energies were obtained for both isotopic product channels. Theoretically, reduced dimensionality quantum dynamics calculations were performed for the HCl + CD3 channel, and the results are in excellent agreement with experimental findings. Comparisons with previously reported results on Cl + CH4/CD4, both experimental and theoretical, were also made to gain deeper insights into the dynamics of this benchmark atom + polyatomic reaction. [source]

The formation of neutral CCCO2H and HCCCO2 molecules from anionic precursors in the gas phase: a joint experimental and theoretical study

RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 24 2005
Mark Fitzgerald
Calculations at the CCSD(T)/aug-cc-pVDZ//B3LYP/6-31G(d) level of theory indicate that the anions ,CCCO2H and HCCCO are stable species in their singlet states. Upon collision-induced, vertical one-electron oxidation under neutralisation-reionisation (,NR+) conditions, they produce the neutral molecules CCCO2H and HCCCO2, respectively. Some of the CCCO2H neutrals should be stable for the duration of the neutralisation-reionisation experiment (10,6,s), while others will dissociate to CCCO and OH (requires 125,kJ,mol,1). In contrast, neutral HCCCO2 is expected to be much less stable, and dissociate to HCC and CO2 (37,kJ,mol,1). Neither CCCO2H nor HCCCO2 is expected to interconvert, or to rearrange to other isomers. The anions ,CCCO2H and HCCCO have been formed in the ion source of the mass spectrometer by the reactions between (CH3)3SiCCCO2H and F, and HCCCO2Si(CH3)3 and F,, respectively. The ,NR+ spectrum of ,CCCO2H shows a recovery signal and also indicates that the lowest energy dissociation pathway of neutral CCCO2H corresponds to the loss of OH. The ,NR+ spectrum of HCCCO2 displays little or no recovery signal, and the spectrum is dominated by the [CO2]+ ion. The experimental observations are in agreement with the predictions of the extensive theoretical studies. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Exciton Migration in Conjugated Dendrimers: A Joint Experimental and Theoretical Study

CHEMPHYSCHEM, Issue 18 2009
Muhammet E. Köse Prof.
Abstract We report a joint experimental and theoretical investigation of exciton diffusion in phenyl-cored thiophene dendrimers. Experimental exciton diffusion lengths of the dendrimers vary between 8 and 17 nm, increasing with the size of the dendrimer. A theoretical methodology is developed to estimate exciton diffusion lengths for conjugated small molecules in a simulated amorphous film. The theoretical approach exploits Fermi's Golden Rule to estimate the energy transfer rates for a large ensemble of bimolecular complexes in random relative orientations. Utilization of Poisson's equation in the evaluation of the Coulomb integral leads to very efficient calculation of excitonic couplings between the donor and the acceptor chromophores. Electronic coupling calculations with delocalized transition densities revealed efficient coupling pathways in the bulk of the material, but do not result in strong couplings between the chromophores which are calculated for more localized transition densities. The molecular structures of dendrimers seem to be playing a significant role in the magnitude of electronic coupling between chromophores. Simulated diffusion lengths correlate well with the experimental data. The chemical structure of the chromophore, the shape of the transition densities and the exciton lifetime are found to be the most important factors in determining the size of the exciton diffusion length in amorphous films of conjugated materials. [source]