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1

Two-extremum electrostatic potential of metal-lattice plasma and the work function of an electron

Surma S. A., Brona J., Ciszewski A.

Materials Science Poland

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2015

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Vol. 33, No. 2

430--444

EN

Metal-lattice plasma is treated as a neutral two-component two-phase system of 2D surface and 3D bulk. Free electron density and bulk chemical potential are used as intensive parameters of the system with the phase boundary position determined in the crystalline lattice. A semiempirical expression for the electron screened electrostatic potential is constructed using the lattice-plasma polarization concept. It comprises an image term and three repulsion/attraction terms of second and fourth orders. The novel curve has two extremes and agrees with certain theoretical forms of potential. A practical formula for the electron work function of metals and a simplified schema of electronic structure at the metal/vacuum interface are proposed. This yields 10.44 eV for the Fermi energy of free electron gas; ~5.817 eV for the Fermi energy level; 4.509 eV for the average work function of bcc tungsten. Selected data are also given for fcc Cu and hcp Re. For harmonic frequencies 10E16 per s of the self-excited metal-lattice plasma, energy gaps of 14.54 and 8.02 eV are found, which correspond to the bulk and surface plasmons, respectively. Further extension of this thermodynamics and metal-lattice theory based approach may contribute to a better understanding of theoretical models which are employed in chemical physics, catalysis and materials science of nanostructures.

2

Energy-band diagrams and capacity-voltage characteristics of CdxHg₁₋xTe : based variband structures calculated with taking into account dependence of electron affinity on a composition

Voitsekhovskii A. V., Gorn D. I., Nesmelov S. N., Kokhanenko A. P.

Opto-Electronics Review

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2010

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Vol. 18, No. 3

241-245

EN

The purpose of this scientific work is the research of energy-band diagrams and capacity-voltage characteristics of CdxHg₁₋xTe -based variband heteroepitaxial structures with taking into account the dependence of electron affinity on the composition. Numerical simulations of energy-band diagrams and capacity-voltage characteristics for metal-insulator-semiconductor structures based on CdxHg₁₋xTe -variable composition layers are carried out in this work. Energy diagrams are calculated with taking into account the dependence of electron affinity on the composition x of CdxHg₁₋xTe. This dependence was obtained in terms of dependence of the local electroneutrality level on the composition for CdxHg₁₋xTe.

3

Theoretical study of electron affinities for selected diatomic molecules

Wróblewski T., Hubisz K., Antonowicz J.

Optica Applicata

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2010

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Vol. 40, nr 3

601--608

EN

Ab initio Hartree–Fock (HF) methods and different hybrid density functional theories (DFT), i.e., LSDA, BPV86, B3LYP, B3PV91, MPW1PW91, PBEPBE, PBE1PBE, HCTH, THCTH and TPSSTPSS, have been used to evaluate electron affinities (EAs) for selected diatomic molecules. Computations have also been made at the high level ab initio quadratic complete basis set (CBS-Q) method. The results show that HF calculations underestimate and DFT overestimate EA’s values in comparison to experimental data. We obtain the best agreement with experimental values of EA’s in DFT calculations with PBE1PBE, TPSSTPSS, THCTH and PBE1PBE functionals for OH, NaBr, LiBr and F2 molecules, respectively.

4

Potencjały jonizacji oraz powinowactwo elektronowe [Beta]-podstawionych nitroetenów w świetle obliczeń DFT

Mikulska M., Barański A.

Czasopismo Techniczne. Chemia

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2010

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R. 107, z. 1-Ch

205-213

PL

Wytypowano metodę DFT pozwalającą na uzyskanie zadawalającego przybliżenia parametrów geometrycznych oraz potencjałów jonizacji i powinowactwa elektronowego nitroetenu. Wyprowadzono równania korelacyjne umożliwiające oszacowanie wartości IP i EA [Beta]-podstawionych nitroetenów w oparciu o obliczone za pomocą algorytmów B3LYP/6-31G(d) i OVGF/6-31G(d) wartości energii FMO.

EN

The DFT method was found to be the best for satisfactory approximation of geometrical parameters and the ionization potentials and electron affinity of nitroethene. A correlation equations were derived for estimation of the IP and EA values of [Beta]-substituted nitroethenes on the basis of FMO energy values obtained from B3LYP/6-31G (d) and OVGF/6-31G (d) algorithms.

5

Detektory fotoemisyjne na bazie związków AIII BV

Wojas W., Wojas J.

Biuletyn Wojskowej Akademii Technicznej

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2010

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Vol. 59, nr 4

239-260

PL

Autorzy szczegółowo omówili zjawisko ujemnego powinowactwa elektronowego w półprzewodnikach grupy AIII BV w aspekcie jego wykorzystania do konstrukcji czułych detektorów podczerwieni. Pokazano, dlaczego arsenek galu jest najbardziej odpowiednim materiałem z tej grupy związków półprzewodnikowych do wykorzystania zjawiska ujemnego powinowactwa do budowy czułych fotoemiterów. Opisano procesy technologiczne otrzymywania takich emiterów przez nakładanie (napylanie) warstw tlenku cezu na arsenek galu. Wymieniono warunki, jakie powinien spełnić fotoemiter. Podano przykłady budowy i zastosowania detektorów do wykrywania padającego promieniowania bliskiej i średniej podczerwieni.

EN

The authors discuss in detail the phenomena of negative electron affinity for semiconductors AIII BV in aspect of construction of sensitive detectors for infrared radiation. We show that GaAs is the most suitable material of this group of semiconductors for application of negative electron affinity to construct sensitive photoemitters. The technological process of fabrication of these emitters with Cs2O layer on GaAs is described. We present the conditions for the photoemitter. We show the examples of detectors for detecting near infrared and middle infrared radiation.

6

Theoretical Study of Ionization Potential and Electron Affinity of Different Isomers of Pyridone

Ma H. K., Zhang S. F., Zhou Z. Y., Su C. F., Zhao S. L., Wang W. J.

Polish Journal of Chemistry

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2008

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Vol. 82, nr 8

1611-1611

EN

The adiabatic (vertical) ionization potential (IP) and valence electron affinity (EA) of gaseous pyridone have been determined with HF method and three DFT methods: B3LYP, B3P86 and B3PW91 at 6-311++G(d,p) and 6-311++G(2d,2p) ba sis sets. IPs and EAs of pyridone in solutions have been calculated at the B3LYP/6-311++G(d,p) basis set. IPs and EAs of four isomers of pyridone are both positive values. The IPs in solutions are smaller than the results in the gaseous phase and decrease with the in crease of dielectric permittivities in solutions. This finding indicates that the cationic states in solutions are more stable than those in the gaseous phase. All the EAs are negative in the gaseous phase, indicating that the an ionic states are unstable with respect to the electron autodetachment, both adiabatically and vertically.

7

Theoretical Determinations of Ionization Potential and Electron Affinity of Gaseous alfa-Alanine

Lu J., Zhu S., Zhou Z., Wu Q., Zhao G.

Polish Journal of Chemistry

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2006

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Vol. 80, nr 3

471-481

EN

Adiabatic (vertical) ionization potential (IP) and valence electron affinity (EA) of gaseous alfa-alanine have been determined by density functional theory (B3LYP), ab initio Hartree-Fock (HF) calculations and ab initio third order algebraic diagrammatic construction [ADC(3)] Green function method with the 6-311++G** and 6-311G** basis sets, respectively. Eighteen possible conformers of alfa-alanine and its charged states have been optimized, employing density functional theory (B3LYP) with 6-311++G** and 6-311G** basis sets, respectively. In the gas phase, the IPs of all alfa-alanine calculated have positive values and all the EAs are negative, except for VEA2 (+0.555 eV) of 6A, which indicates that all anions except for 6A- are unstable with respect to electron autodetachment vertically and adiabatically. All kinds of chemical quantities, associated with the IP and EA, such as electronegativity, chemical potential, chemical hardness, and chemical softness, have also been determined. Finally, we also report the infrared spectrum frequencies and vibrational modes for neutral states of alfa-alanine 1A, 2A, 3A, 5A and their optimized cationic and anionic states in seven highest frequency regions, and analyzed the relationship between the vibrational frequencies when receiving or donating an electron.

8

Ab initio study of formic acid monomer, dimer and trimer

Ziemczonek L, Wroblewski T, Karwasz G P

Optica Applicata

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2006

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Vol. 36, nr 4

s. 587--591

EN

Configurations of the formic acid monomer, dimer and trimer are presented. The total energies for these structures have been calculated while the negatively charged clusters were considered and the possible pathways of interaction of low energy electrons with monomers and clusters were discussed. Calculations have been executed using 6–311G** and 6–311++G** basis sets. The electron affinities of monomer and clusters are presented. Influence of choice of the molecular basis set is also discussed. Only such systematic studies allow to explain values observed experimentally, for example, in electron attachment experiments on formic acid (Martin I. et al., Phys. Chem. Chem. Phys. 7(10), 2005, p. 2212).

9

Ab initio theoretical study of dipole-bound anions of molecular complexes. Water molecule inhibits or enhances electron affinity of N-methylaminoadenine

Smets J., Smith D.M.A., Elkadi Y., Adamowicz L.

Polish Journal of Chemistry

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1998

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Vol. 72, nr 7S

1615-1623

EN

Ab initio calculations have been performed to determine the electron affinity of the water complex of N-methylaminoadenine (NMA). This complex has been chosen for this study because it can form three different isomeric structures with a water molecule hydrogen- bonded at three different NMA sites, and only two of these structures have sufficient dipole moments to form dipole-bound states with an excess electron. In the third structure, which according to the calculations should be the most stable form, the dipole moments of NMA and the water molecule oppose each other resulting in an almost null dipole moment of the complex, so the complex has no ability to form a stable dipole-bound anion. This detrmination offers an interesting possibility for an experimental investigation of whether the NMA x H2O complex forms an stable anion. If such an anion is detected, it will mean that an electron attachment can increase the gas-phase concentration of the complex, which is thermodynamically less stable in its neutral form.