The composition effect on the bowing parameter in the cubic InGaN, AlGaN and AlInN alloys

Numerical simulation based on FP-LAPW calculations is applied to study direct and indirect band gap energy of the cubic AlxGa₁₋xN, InxGa₁₋xN and InxAl₁₋xN alloys.The direct and indirect band-gap bowing parameter is also calculated, and the values obtained are very important, as we find a strong dependence of the bowing parameter on the composition

Auger Resonant Raman Spectroscopy Used to Study the Angular Distributions of the Xe 4d5/2 → 6p Decay Spectrum

The Auger resonant Raman effect can be used as a method to eliminate natural lifetime broadening in resonant Auger spectra. We have coupled this method with high-resolution photons from the Advanced Light Source to study angular distributions and decay rates of the Xe4d5/2→6p resonant Auger lines. The angular distribution parameters β of almost all possible final ionic 5p4(3P, 1D, 1S)6p states have been determined. Our data, which remove the discrepancy between previous lower-resolution experimental results, are compared to different theoretical results

The first principle calculation of electronic and optical properties of AlN, GaN and InN compounds under hydrostatic pressure

Numerical simulation based on FPLAPW calculations is applied to study the lattice parameters, bulk modulus, band energy and optical properties of the zincblende binary solids AlN, GaN, InN under hydrostatic pressure. The results obtained are in a good agreement with experimental and theoretical values

Mirroring doubly excited resonances in argon.

New features are revealed in the low-energy photoionization spectrum of Ar by critically combining high photon resolution and differential photoelectron spectroscopic techniques. Two LS-forbidden doubly excited resonances are seen in the 3p−13/2,1/2 partial cross sections which exhibit mirroring profiles, resulting in complete cancellation in the total photoionization cross section, as was predicted by Liu and Starace [Phys. Rev. A 59, R1731 (1999)]. These results demonstrate that a new class of weakly spin-orbit induced, mirroring resonances should be observable in partial, but not in total, collisional cross sections involving atoms, molecules, and solids in general

Experimental evidence of a dynamic Jahn-Teller effect in C+60.

Detailed analysis of the highest occupied molecular orbital band shape in the photoelectron spectrum of gaseous C60 reveals a dynamic Jahn-Teller effect in the ground state of C+60. The direct observation of three tunneling states asserts a D3d geometry for the isolated cation, originating from a strong vibronic coupling. These results show that the ionic motion plays an important role in the electron-phonon interaction

Coincident energy and angular distributions in xenon 4d_5/2 inner-shell double photoionization

We report on measurements of the triply differential cross section for the 4d(5/2) inner-shell photoionization in xenon followed by N(5)O(2,3)O(2,3) Auger decay using electron-electron coincidence spectroscopy. The experimental setup made it possible to obtain the first coincident angular distributions for the (1D2) and (3P2) final states at a photon energy of 97.45 eV. Relative amplitudes and phases describing the photoionization were estimated from these angular distributions

Angle-resolved two-dimensional mapping of electron emission from the inner-shell 2p excitations in Cl₂

Angle-resolved Auger and valence photoelectron spectra were measured over a 14-eV photon energy range across the Cl2 2p ionization thresholds. The measurements were carried out using highly efficient time-of-flight spectrometers coupled with photons from the Atomic and Molecular undulator beamline of the Advanced Light Source and an advanced data-acquisition system. Auger-electron spectra of 2→pσ* and 2→pnl resonances were analyzed and the evolution of the resonant Auger to the normal Auger decay distorted by postcollision interaction was examined. We find that valence photoionization channels do not resonate strongly at the photon energies of the core-to-Rydberg excitation, in contrast to the strongly resonating ones observed in the HCl molecule. Auger decay spectra of the 2p−1σ* resonances showed no evidence of atomic transitions in Cl*, also in contrast to HCl. In addition, angular distribution of the photoelectron and Auger-electron lines was derived

Compton double-to-single ionization ratio of helium at 57 keV

We have measured the Compton double-to-single ionization ratio of helium using an ion time-of-flight spectrometer along with monochromatized synchrotron radiation of 57 keV. This photon energy is high and probes the Compton ionization alone, since the photoionization makes only a negligible contribution to the total cross section. Comparing our result, which is (1.25±0.3)%, with theoretical calculations and measurements at lower energies shows that this energy is most likely still not high enough to confirm the value of the asymptotic high-energy limit experimentally