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Full-Text Articles in Materials Chemistry
Coherent Vibrational Oscillation In Gold Prismatic Monolayer Periodic Nanoparticle Arrays, Wenyu Huang, Wei Qian, Mostafa A. El-Sayed
Coherent Vibrational Oscillation In Gold Prismatic Monolayer Periodic Nanoparticle Arrays, Wenyu Huang, Wei Qian, Mostafa A. El-Sayed
Wenyu Huang
We studied the ultrafast laser-induced coherent phonon oscillation in prismatic shaped gold nanoparticles assembled in monolayer periodic arrays by using the nanosphere lithographic technique. The amplitude and phase of the oscillation observed by ultrafast pump−probe transient spectroscopy is monitored as the wavelength of the dipolar surface plasmon absorption decreases. At a certain wavelength, the oscillation could not be observed. As the monitoring wavelength decreases further, the sign of the amplitude changes. From the wavelength at which the oscillation is not detected, the dependence of the absorption maxima on the size of the nanoparticles, the changes in the nanoparticle size are …
Photochemical Generation Of Nitrenium Ions From Protonated 1,1-Diarylhydrazines, Arthur Winter, Selina I. Thomas, Andrew C. Kung, Daniel E. Falvey
Photochemical Generation Of Nitrenium Ions From Protonated 1,1-Diarylhydrazines, Arthur Winter, Selina I. Thomas, Andrew C. Kung, Daniel E. Falvey
Arthur Winter
Laser flash photolysis experiments, chemical trapping studies, and time-dependent density functional theory calculations demonstrate that photolysis of protonated 1,1-diarylhydrazines generates N,N-diarylnitrenium ions.
Effect Of Meta Electron-Donating Groups On The Electronic Structure Of Substituted Phenyl Nitrenium Ions, Arthur Winter
Effect Of Meta Electron-Donating Groups On The Electronic Structure Of Substituted Phenyl Nitrenium Ions, Arthur Winter
Arthur Winter
Density functional theory (UB3LYP/6-31G(d,p)) was used to determine substituent effects on the singlet−triplet-state energy gap for 21 meta-substituted phenylnitrenium ions. It was found that strongly electron-donating substituents stabilize the triplet state relative to the singlet state. With sufficiently strong meta electron donors (e.g., m,m‘-diaminophenylnitrenium ion) the triplet is predicted to be the ground state. Analysis of equilibrium geometries, Kohn−Sham orbital distributions, and Mulliken spin densities for the triplet states of this series of nitrenium ions leads to the conclusion that there are two spatially distinct types of low-energy triplet states. Simple arylnitrenium ions such as phenylnitrenium ions as well as …