Accurateab initiostudy of the energetics of phosphorus nitride: Heat of formation, ionization potential, and electron affinity

2003 ◽  
Vol 118 (18) ◽  
pp. 8290-8295 ◽  
Author(s):  
Andre E. Kemeny ◽  
Joseph S. Francisco ◽  
David A. Dixon ◽  
David Feller
Keyword(s):  
Ionization Potential ◽  
Electron Affinity ◽  
Heat Of Formation

Introduction

2003 ◽  
Author(s):  
Toshiaki Enoki ◽  
Morinobu Endo ◽  
Masatsugu Suzuki
Keyword(s):  
Electronic Structure ◽  
Charge Transfer ◽  
Ionization Potential ◽  
Molecular Orbital ◽  
Electron Affinity ◽  
Basic Unit ◽  
Charge Transfer Complexes ◽  
Vacuum Level ◽  
2D System ◽  
Lowest Unoccupied Molecular Orbital

There are two important features in the structure and electronic properties of graphite: a two-dimensional (2D) layered structure and an amphoteric feature (Kelly, 1981). The basic unit of graphite, called graphene is an extreme state of condensed aromatic hydrocarbons with an infinite in-plane dimension, in which an infinite number of benzene hexagon rings are condensed to form a rigid planar sheet, as shown in Figure 1.1. In a graphene sheet, π-electrons form a 2D extended electronic structure. The top of the HOMO (highest occupied molecular orbital) level featured by the bonding π-band touches the bottom of the LUMO (lowest unoccupied molecular orbital) level featured by the π*-antibonding band at the Fermi energy EF, the zero-gap semiconductor state being stabilized as shown in Figure 1.2a. The AB stacking of graphene sheets gives graphite, as shown in Figure 1.3, in which the weak inter-sheet interaction modifies the electronic structure into a semimetallic one having a quasi-2D nature, as shown in Figure 1.2b. Graphite thus features a 2D system from both structural and electronic aspects. The amphoteric feature is characterized by the fact that graphite works not only as an oxidizer but also as a reducer in chemical reactions. This characteristic stems from the zero-gap-semiconductor-type or semimetallic electronic structure, in which the ionization potential and the electron affinity have the same value of 4.6 eV (Kelly, 1981). Here, the ionization potential is defined as the energy required when we take one electron from the top of the bonding π-band to the vacuum level, while the electron affinity is defined as the energy produced by taking an electron from the vacuum level to the bottom of the anti-bonding π*-band. The amphoteric character gives graphite (or graphene) a unique property in the charge transfer reaction with a variety of materials: namely, not only an electron donor but also an electron acceptor gives charge transfer complexes with graphite, as shown in the following reactions: . . .xC + D → D+ C+x. . . . . .(1.1). . . . . .xC + A → C+x A−. . . . . .(1.2). . . where C, D, and A are graphite, donor, and acceptor, respectively.

Quantitation of Secondary Ion Mass Spectrometry (SIMS) for HgCdTe.

1983 ◽  
Vol 25 ◽  
Author(s):  
Lawrence E. Lapides ◽  
George L. Whiteman ◽  
Robert G. Wilson
Keyword(s):  
Mass Spectrometry ◽  
Ion Implantation ◽  
Ionization Potential ◽  
Electron Affinity ◽  
Secondary Ion Mass Spectrometry ◽  
Relative Sensitivity ◽  
Depth Profiles ◽  
Ion Mass Spectrometry ◽  
Sensitivity Factors ◽  
Secondary Ion

ABSTRACTQuantitative depth profiles of impurities in LPE layers of HgCdTe have been determined using relative sensitivity factors calculated from ion implantation profiles. Standards were provided for Li, Be, B, C, F, Na, Mg, Al, Si, P, S, Cl, Cu, Ga, As, Br, and In. Relative sensitivity factors as a function of ionization potential for O2+ primary ion SIMS and electron affinity for Cs+ primary ion SIMS have been calculated in order to extend quantitation to elements not yet implanted. Examples of depth profiles for implant standards and unimplanted layers are given.

scholarly journals Variations of ionization potential and electron affinity as a function of surface orientation: The case of orthorhombic SnS

2014 ◽  
Vol 104 (21) ◽  
pp. 211603 ◽  
Author(s):  
Vladan Stevanović ◽  
Katy Hartman ◽  
R. Jaramillo ◽  
Shriram Ramanathan ◽  
Tonio Buonassisi ◽  
...  
Keyword(s):  
Ionization Potential ◽  
Electron Affinity ◽  
Surface Orientation

Experimental and theoretical studies of proton removal from propene

1978 ◽  
Vol 56 (1) ◽  
pp. 131-140 ◽  
Author(s):  
Gervase I. Mackay ◽  
Min H. Lien ◽  
Alan C. Hopkinson ◽  
Diethard K. Bohme
Keyword(s):  
Proton Affinity ◽  
Electron Affinity ◽  
Rate Constants ◽  
Equilibrium Constants ◽  
Standard Free Energy ◽  
Proton Transfer Reaction ◽  
Heat Of Formation ◽  
Molecular Orbital Calculations ◽  
Standard Free Energy Change ◽  
Methyl Proton

The kinetics and energetics of proton removal from propene, which contains several sites of different acidities, were investigated both theoretically and experimentally. Rate and equilibrium constants were measured for the proton-transfer reaction [Formula: see text]at 296 ± 2 K using the flowing afterglow technique. The rate constants were determined to be kforward = (1.1 ± 0.3) × 10−9 cm3 molecule−1 s−1 and kreverse = (5.4 ± 1.9) × 10−10 cm3 molecule−1 s−1. The ratio of rate constants, kf/kr = 2.1 ± 0.7, was found to be in agreement with the equilibrium constant, K = 2.2 ± 0.8, determined from equilibrium concentrations. Abinitio molecular orbital calculations predicted the removal of a methyl proton from propene to yield the allyl anion to be energetically favoured. This prediction was supported by measurements of deuteron removal from CD3CHCH2. The measured value of K corresponds to a standard free energy change, ΔG0298, of −0.44 ± 0.14 kcal mol−1 which provided values for the standard enthalpy change ΔH0298 = +0.5 ± 0.4 kcal mol−1, the proton affinity, PA298(C3H5−) = 391 ± 1 kcal mol−1, the heat of formation, ΔH0f,298(C3H5−) = 29.0 ± 0.8 kcal mol−1, and the electron affinity EA(CH2CHCH2) = 12.4 ± 1.9 kcal mol−1. The experimentally established value for the proton affinity of the allyl anion was in reasonable accord with the value of 422.3 kcal mol−1 determined by calculation. The electron affinity of the allyl radical derived in this study is supported by previous calculations and several limiting values obtained experimentally.

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