Unusual evolution of the lowest unoccupied state inGa(As0.5−yP0.5−yN2y)

2000 ◽  
Vol 62 (23) ◽  
pp. 15311-15314 ◽  
Author(s):  
L. Bellaiche ◽  
N. A. Modine ◽  
E. D. Jones
Keyword(s):  
Unoccupied State

Optical Properties of the Pb Center at the Si/SiO2 Interface

1985 ◽  
Vol 46 ◽  
Author(s):  
Arthur H. Edwards ◽  
W. Beall Fowler
Keyword(s):  
Valence Band ◽  
Conduction Band ◽  
Defect State ◽  
Polarization Effects ◽  
Unoccupied State ◽  
Cluster Calculations ◽  
Occupied State ◽  
Order Of Magnitude ◽  
Neutral Defect ◽  
Theoretical Results

AbstractWe present theoretical results for the optical prooerties of the Pb center at the Si/SiO2 interface. Using wave functions obtainec from semiempirical (MINDO/3) cluster calculations, we have calculated electric dipole matrix elements connecting the singly occupied (neutral) defect state to the unoccupied conduction-band-like states, as well as those connecting the occupied valence-band-like states to the singly occupied defect state and to the unoccupied defect state. We predict the absorption cross section for excitation from the valence band to the unoccupied state to be of order 10−19 cm2 and that for excitation from the valence band to the occupied state and from the occupied state to the conduction band to be an order of magnitude larger. We also predict that the absorption will in some cases be strongly dependent on the direction of the polarization. Effects of symmetry lowering in the oxide and of distortions in the silicon are discussed.

Unoccupied-state electronic structure in (NiyPt1−y)75P25andNi100−xPxmetallic glasses

1985 ◽  
Vol 32 (12) ◽  
pp. 7670-7675 ◽  
Author(s):  
M. Choi ◽  
D. M. Pease ◽  
W. A. Hines ◽  
G. H. Hayes ◽  
J. I. Budnick ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Unoccupied State

Cleanroom Fan Energy Reduction—Airflow Control Retrofit Based on Continuous, Real-time Particle Sensing

2019 ◽  
Vol 62 (1) ◽  
pp. 11-25
Author(s):  
Wei Sun
Keyword(s):  
Real Time ◽  
High Volume ◽  
High Tech ◽  
Average Particle ◽  
Particle Generation ◽  
Commercial Space ◽  
Unoccupied State ◽  
Occupied State ◽  
Fan Speed ◽  
Save Energy

Abstract Cleanrooms are utilized in electronics, semiconductor, aerospace, pharmaceutical, automotive, optical, medical device, and food processing facilities where air cleanliness is required to prevent defects in high-tech or high-value products. Compared to general commercial space, cleanrooms typically use 5 to 50 times the energy for the same area. One key reason is the high volume of conditioned and filtered air required to make the room air cleaner, which is measured in room-average particle concentration. The technology in this study uses real-time continuous particle sensors as feedback signals to automatically adjust fan speed. The system can modulate fan speed and provide the correct amount of airflow into the cleanroom to prevent over-supply and save energy. In typical manufacturing cleanrooms, the unoccupied state (evenings and weekends) is approximately two times longer than the occupied state (operational work hours), and particle generation (from personnel, equipment, and process) is much lower during the unoccupied state. Limited components and parts are required to apply the technology in this study into the design of a new cleanroom or to integrate the technology into existing cleanroom fan systems.

Spectroscopic states of PTCDA negative ions and their relation to the maxima of unoccupied state density in the conduction band

2011 ◽  
Vol 56 (6) ◽  
pp. 754-759 ◽  
Author(s):  
S. A. Pshenichnyuk ◽  
A. V. Kukhto ◽  
I. N. Kukhto ◽  
A. S. Komolov
Keyword(s):  
Conduction Band ◽  
Negative Ions ◽  
State Density ◽  
Unoccupied State

On the Annihilation of Positrons

1936 ◽  
Vol 32 (1) ◽  
pp. 158-160 ◽  
Author(s):  
J. C. Jaeger ◽  
H. R. Hulme
Keyword(s):  
Negative Energy ◽  
Atomic Electron ◽  
Single Quantum ◽  
Unoccupied State ◽  
Negative Energy States ◽  
Energy States

We shall discuss the annihilation of positrons by a process in which only one quantum of light is emitted. The positive electron is regarded as a hole or unoccupied state in the distribution of electrons in negative energy states, and is destroyed by an atomic electron jumping down into it with the emission of a single quantum. This process is only possible in the presence of a nucleus, which can take up the momentum liberated, and is therefore most probable when the atomic electron is a K-electron.

Electronic Structures of Icosahedral C60 and C60X (X=K, O and Cl) Clusters

1990 ◽  
Vol 206 ◽  
Author(s):  
Susumu Saito
Keyword(s):  
Electronic Structures ◽  
Energy Gap ◽  
Local Density ◽  
Alkali Metal Atom ◽  
Foreign Atom ◽  
Exchange Correlation ◽  
Exchange Correlation Potential ◽  
Unoccupied State ◽  
Occupied State ◽  
Correlation Potential

ABSTRACTI report the electronic structures of “buckminsterfullerene”, C60 cluster with truncated-icosahedron geometry, and C60X where X is a foreign atom trapped at the center of the C60 cage (X=K, O, and Cl). The local-density approximation with Xα exchange-correlation potential is used. The obtained electronic structure of C60 has a rather large energy gap between the completely occupied highest-occupied state and the lowest-unoccupied state, in accord with previous calculations. In the case of C60K, a valence electron of an alkali-metal atom is found to transfer to the outer C60 surface. On the other hand, in C60O and C60Cl, 2p state of O and 3p state of Cl appear inside the energy gap of the pure C60 cluster. Such variety of results indicates great possibilities of C60X as constructing units of new materials.

A Microscopic Self-consistent Calculation with Saturation Diagrams in 16O

1975 ◽  
Vol 53 (20) ◽  
pp. 2261-2266 ◽  
Author(s):  
B. Rouben ◽  
R. Padjen ◽  
D. Gogny ◽  
P. Pirès
Keyword(s):  
State Space ◽  
Single Particle ◽  
Charge Radius ◽  
Particle Removal ◽  
Unoccupied State ◽  
Self Consistent ◽  
G Matrices ◽  
Self Consistency ◽  
Better Than ◽  
Single Particle Basis

Self-consistent calculations are performed in 16O with effective G matrices obtained from two different soft core interactions. The calculations possess the 'triple' self-consistency: (a) on the single particle basis, (b) on the single particle eigenvalues (Brueckner self-consistency), and (c) on the occupation probabilities. Two different procedures of calculating the latter are carried out, one involving a truncation of the unoccupied state space, one involving no truncation. The truncation effects are studied and shown to increase with the hardness of the interaction. A comparison is also made to calculations where the Brueckner self-consistency is satisfied only on the average. The total and single particle removal energies for both forces are quite satisfactory, the Pirès – Gogny – de Tourreil interaction performing slightly better than that of de Tourreil – Sprung. The charge radius is approximately 10% too small.

scholarly journals Mapping the unoccupied state dispersions in Ta2NiSe5 with resonant inelastic x-ray scattering

2020 ◽  
Vol 102 (8) ◽  
Author(s):  
C. Monney ◽  
M. Herzog ◽  
A. Pulkkinen ◽  
Y. Huang ◽  
J. Pelliciari ◽  
...  
Keyword(s):  
X Ray ◽  
X Ray Scattering ◽  
Unoccupied State ◽  
Ray Scattering

Electronic Structures of Halogenated Polysilanes

1997 ◽  
Vol 486 ◽  
Author(s):  
Hideshi Motoyama ◽  
Kyozaburo Takeda ◽  
Kenji Shiraishi
Keyword(s):  
Band Gap ◽  
Electronic Structures ◽  
Visible Range ◽  
Energy Position ◽  
Unoccupied State ◽  
Valence Electrons ◽  
Orbital Mixing ◽  
Valence Bands ◽  
Halogen Species ◽  
Valence Band Splitting

AbstractThe electronic structures of halogenated polysilanes (PSi), whose side chains are replaced by halogen (X) atoms, have been theoretically investigated based on the firstprinciples calculations. It was found that non-bonding (n) electrons localizing at the X atom produce an important orbital mixing with the u valence electrons delocalized in the direction of the PSi skeleton (a-n mixing). This a-n mixing splits the top of the valence bands, and creates unoccupied states in the band gap. This valence-band-splitting effectively narrows the band gap to the visible range, and the unoccupied state in the band gap has the potential to be an electron acceptor. Moreover, we also investigated several replacement patterns as well as the kind of replaced halogen species (X=F, Cl, Br, I). The dispersion and energy position of the unoccupied state(s) can be artificially tuned by these chemical modifications. Thus, halogenation can change PSi into optelectronic polymers with visible photoluminescence.

Electronic-structure evolution of SrFeO3-x during topotactic phase transformation

2021 ◽  
Author(s):  
Jiali Zhao ◽  
Kaihui Chen ◽  
Shi-En Li ◽  
Qinghua Zhang ◽  
Jia-Ou Wang ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Electronic Structure ◽  
Clean Energy ◽  
Underlying Mechanism ◽  
Structure Evolution ◽  
Energy Field ◽  
Unoccupied State ◽  
Abo3 Perovskite ◽  
Fundamental Understanding ◽  
Brownmillerite Structure

Abstract Oxygen-vacancy-induced topotactic phase transformation between the ABO2.5 brownmillerite structure and the ABO3 perovskite structure attracts ever-increasing attention due to the perspective applications in catalysis, clean energy field, and memristors. However, a detailed investigation of the electronic-structure evolution during the topotactic phase transformation for understanding the underlying mechanism is highly desired. In this work, multiple analytical methods were used to explore evolution of the electronic structure of SrFeO3-x thin films during the topotactic phase transformation. The results show that the increase in oxygen content produces a new unoccupied state of O 2p character near the Fermi energy, inducing the insulator-to-metal transition. More importantly, the hole states are more likely constrained to the dx2-y2 orbital than to the d3z2-r2 orbital. Our results reveal an unambiguous evolution of the electronic structure of SrFeO3-x films during topotactic phase transformation, which is crucial not only for fundamental understanding but also for perspective applications such as solid-state oxide fuel cells, catalysts, and memristor devices.

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