Search results for "Ionization Energy"
showing 10 items of 83 documents
Effect of melting on ionization potential of sodium clusters
2003
The effect of melting transition on the ionization potential has been studied for sodium clusters with 40, 55, 142, and 147 atoms, using ab initio and classical molecular dynamics. Classical and ab initio simulations were performed to determine the ionization potential of Na142 and Na147 for solid, partly melted, and liquid structures. The results reveal no correlation between the vertical ionization potential and the degree of surface disorder, melting, or the total energy of the cluster obtained with the ab initio method. However, in the case of 40 and 55 atom clusters, the ionization potential seems to decrease when the cluster melts.
Frequency tripling for resonance ionization spectroscopy (RIS) of Cd
1998
To explore the nucleosynthesis of heavy elements in the rapid neutron-capture process, investigations on short- lived, very neutron-rich Cd isotopes are planned that require pure samples. These will be produced at the CERN-ISOLDE on-line mass separator in combination with a chemically se- lective laser ion source. The excitation scheme for resonance ionization of Cd was tested in Mainz with a copper-vapor- pumped dye laser system. Due to the high ionization potential of Cd, frequency tripling was required for the first excita- tion step.1D 228: 8n m/. Laser light with an average power of 2m Wwas obtained after frequency tripling and was suc- cessfully used for RIS test measurements on cadmi…
Ionization potential of aluminum clusters
1998
Structure, electronic structure, and ionization potential of aluminum clusters of 2–23 atoms are studied with a total energy method based on the density-functional theory. The calculated adiabatic ionization potentials agree remarkably well with the data from threshold photoionization measurements. The analysis of results gives insight into hybridization effects in the smallest clusters as well as reveals certain clusters that exhibit a clear jellium-type shell structure. An explanation of the experimental results in the size region of 12–23 atoms is given in terms of coexisting, competing icosahedral, decahedral, and fcc-based clusters. @S0163-1829~98!00228-8#
Nuclear shell model applied to metallic clusters
1993
We apply the nuclear shell model to jellium clusters of up to twenty-one Na atoms. Binding energies, ionization potentials, and photoabsorption cross sections are calculated and compared with mean-field results.
Influence of hole transport material ionization energy on the performance of perovskite solar cells
2019
Halide perovskites have shown excellent photophysical properties for solar cell applications which led to a rapid increase of the device efficiency. Understanding the charge carrier dynamics within the active perovskite absorber and at its interfaces will be key to further progress in their development. Here we present a series of fully evaporated devices employing hole transport materials with different ionization energies. The open circuit voltage of the devices, along with their ideality factors, confirm that the former is mainly determined by the bulk and surface recombination in the perovskite, rather than by the energetic offset between the valence band of the perovskite and the highe…
Electronic functionality of Gd-bisphthalocyanine: Charge carrier concentration, charge mobility, and influence of local magnetic field
2018
Abstract Gadolinium bisphthalocyanine (GdPc2) has been placed among the highest ranked molecular materials considered namely for modern optoelectronic applications including organic solar cells. To improve understanding of the correlation between GdPc2 magnetic properties and its electronic functionality, we experimentally and theoretically studied charge carrier concentration, charge mobility, and influence of local magnetic field on charge carrier transport. For better clearance, all the main studied properties of GdPc2 bisphthalocyanine were compared with Zn phthalocyanine (ZnPc) as a reference material. Conductivity and charge carrier mobility were measured in materials incorporated in …
Photoluminescence study of excitons in homoepitaxial GaN
2001
High-resolution photoluminescence spectra have been measured in high-quality homoepitaxial GaN grown on a free-standing GaN substrate with lower residual strain than in previous work. Unusually strong and well-resolved excitonic lines were observed. Based on free- and bound exciton transitions some important GaN parameters are derived. The Arrhenius plot of the free A exciton recombination yields a binding energy of 24.7 meV. Based on this datum, an accurate value for the band-gap energy, EG(4.3 K) = 3.506 eV, can be given. From the donor bound excitons and their “two-electron” satellites, the exciton localization energy and donor ionization energy are deduced. Finally, estimates of the ele…
Derivatives of indandione and differently substituted triphenylamine with charge-transporting and NLO properties
2015
Abstract Derivatives containing electron-donaiting triphenylamino groups and electron-withdrawing indandione moieties were synthesized and their thermal, electrochemical, photoelectrical and nonlinear optical properties were studied. The synthesized compounds form glasses with the glass transition temperatures ranging from 69 to 118 °C. The ionization potentials of the solid samples of the synthesized materials were found to be in the range of 5.48–5.69 eV. Hole-drift mobilities estimated by xerographic time of flight technique in the amorphous layers of 2-({4-[(4-{[(2E)-1,3-dioxo-2,3-dihydro-1H-inden-2-ylidene]methyl}phenyl)(4-methoxyphenyl)amino]phenyl}methylidene)-2,3-dihydro-1H-indene-1…
Evolution of the electronic properties of graded poly(thienylene vinylene)-poly(pyrrylene vinylene) mixed copolymers
1993
Abstract We present a valence effective Hamiltonian (VEH) theoretical investigation of the evolution of the electronic properties of poly(thienylene vinylene)-poly(pyrrylene vinylene) mixed copolymers as a function of the unit cell content on the basis of ab initio 3–21G∗ and 3–21G optimized geometries. As a consequence of the strong localization of the LUCO both electron affinity and bandgap deviate from a linear dependence, and only the ionization potential presents the expected values.
VEH electronic band structure of poly(phenylsilane)
1993
Abstract The electronic structure of all-trans syndiotactic and isotactic poly(phenylsilane) has been calculated using the valence effective Hamiltonian (VEH) method. The effects of attachment of the phenyl group on the electronic properties of polysilane are analysed in detail. The VEH results show a decrease of ionization potential and an increase of electron affinity which determine an important reduction of the bandgap. These features are correlated with σ−π and σ ∗ −π ∗ interactions between the silicon backbone and the phenyl group.