Ionization Energy

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Daniel Fink - One of the best experts on this subject based on the ideXlab platform.

  • determination of the first Ionization Energy of polonium by resonance Ionization spectroscopy part ii measurement of odd parity rydberg states at cern isolde
    Spectrochimica Acta Part B: Atomic Spectroscopy, 2019
    Co-Authors: Daniel Fink, K Blaum, V N Fedosseev, B A Marsh, R E Rossel, S Rothe
    Abstract:

    Abstract Polonium (Po) is one of the rarest elements in Earth's crust. None of its isotopes are stable and sufficient amounts for systematic experimental studies of its most fundamental properties are only available by artificial production. At the radioactive ion beam facility ISOLDE at CERN, 208Po was produced by proton-induced spallation of uranium. Using the technique of in-source Resonance Ionization Spectroscopy the Ionization threshold was probed with a tunable dye laser. A spectrum of 110 previously undocumented odd-parity Rydberg states was observed. Applying the Rydberg formalism to the data enabled the determination of the first Ionization Energy of polonium as 67896.310(14)(30) cm−1 or 8.4180700(18)(37) eV. This is a precision improvement of more than 600 over the existing literature value. A comparison with the homologous elements sulfur, selenium and tellurium enabled the assignment of the electron configuration of the resonances found in the spectrum.

Kenneth R Graham - One of the best experts on this subject based on the ideXlab platform.

  • processing dependent influence of the hole transport layer Ionization Energy on methylammonium lead iodide perovskite photovoltaics
    ACS Applied Materials & Interfaces, 2018
    Co-Authors: So Min Park, Samuel M Mazza, Zhiming Liang, Ashkan Abtahi, Alex M Boehm, Sean Parkin, John E Anthony, Kenneth R Graham
    Abstract:

    Organometal halide perovskite photovoltaics typically contain both electron and hole transport layers, both of which influence charge extraction and recombination. The Ionization Energy (IE) of the hole transport layer (HTL) is one important material property that will influence the open-circuit voltage, fill factor, and short-circuit current. Herein, we introduce a new series of triarylaminoethynylsilanes with adjustable IEs as efficient HTL materials for methylammonium lead iodide (MAPbI3) perovskite based photovoltaics. The three triarylaminoethynylsilanes investigated can all be used as HTLs to yield PV performance on par with the commonly used HTLs PEDOT:PSS and Spiro-OMeTAD in inverted architectures (i.e., HTL deposited prior to the perovskite layer). We further investigate the influence of the HTL IE on the photovoltaic performance of MAPbI3 based inverted devices using two different MAPbI3 processing methods with a series of 11 different HTL materials, with IEs ranging from 4.74 to 5.84 eV. The re...

  • Processing Dependent Influence of the Hole Transport Layer Ionization Energy on Methylammonium Lead Iodide Perovskite Photovoltaics
    2018
    Co-Authors: So Min Park, Samuel M Mazza, Zhiming Liang, Ashkan Abtahi, Alex M Boehm, John E Anthony, Sean R. Parkin, Kenneth R Graham
    Abstract:

    Organometal halide perovskite photovoltaics typically contain both electron and hole transport layers, both of which influence charge extraction and recombination. The Ionization Energy (IE) of the hole transport layer (HTL) is one important material property that will influence the open-circuit voltage, fill factor, and short-circuit current. Herein, we introduce a new series of triarylamino­ethynylsilanes with adjustable IEs as efficient HTL materials for methyl­ammonium lead iodide (MAPbI3) perovskite based photovoltaics. The three triarylamino­ethynylsilanes investigated can all be used as HTLs to yield PV performance on par with the commonly used HTLs PEDOT:PSS and Spiro-OMeTAD in inverted architectures (i.e., HTL deposited prior to the perovskite layer). We further investigate the influence of the HTL IE on the photovoltaic performance of MAPbI3 based inverted devices using two different MAPbI3 processing methods with a series of 11 different HTL materials, with IEs ranging from 4.74 to 5.84 eV. The requirements for the HTL IE change based on whether MAPbI3 is formed from lead acetate, Pb­(OAc)2, or PbI2 as the Pb source. The ideal HTL IE range is between 4.8 and 5.3 eV for MAPbI3 processed from Pb­(OAc)2, while with PbI2 the PV performance is relatively insensitive to variations in the HTL IE between 4.8 and 5.8 eV. Our results suggest that contradictory findings in the literature on the effect of the HTL IE in perovskite photovoltaics stem partly from the different processing methods employed

Kaichung Lau - One of the best experts on this subject based on the ideXlab platform.

  • high level ab initio predictions for the Ionization Energy bond dissociation energies and heats of formation of vanadium methylidyne radical and its cation vch vch
    Journal of Physical Chemistry A, 2019
    Co-Authors: Chowshing Lam, Kaichung Lau
    Abstract:

    The Ionization Energy (IE) of VCH, the 0 K V–CH/VC–H bond dissociation energies (D0s), and the heats of formation at 0 K (ΔHf0°) and 298 K (ΔHf298°) for VCH/VCH+ are predicted by the wave function-based CCSDTQ/CBS approach. This composite-coupled cluster method includes full quadruple excitations in conjunction with the approximation to the complete basis set (CBS) limit. The contributions of zero-point vibrational Energy, core–valence (CV) correlation, spin–orbit coupling, and scalar relativistic corrections are taken into account. The present calculations show that adiabatic IE(VCH) = 6.785 eV and demonstrate excellent agreement with an IE value of 6.774 7 ± 0.000 1 eV measured with two-color laser-pulsed field Ionization-photoelectron spectroscopy. The CCSDT and MRCI+Q methods which include CV correlations give the best predictions of harmonic frequencies: ω2 (ω2+) (bending) = 534 (650) and 564 (641) cm–1 and the V–CH stretching ω3 (ω3+) = 835 (827) and 856 (857) cm–1 compared with the experimental val...

  • high level ab initio predictions for the Ionization Energy electron affinity and heats of formation of cyclopentadienyl radical cation and anion c5h5 c5h5 c5h5
    Journal of Physical Chemistry A, 2014
    Co-Authors: Kaichung Lau
    Abstract:

    The Ionization Energy (IE), electron affinity (EA), and heats of formation (ΔH°f0/ΔH°f298) for cyclopentadienyl radical, cation, and anion, C5H5/C5H5+/C5H5–, have been calculated by wave function-based ab initio CCSDT/CBS approach, which involves approximation to complete basis set (CBS) limit at coupled-cluster level with up to full triple excitations (CCSDT). The zero-point vibrational Energy correction, core–valence electronic correction, scalar relativistic effect, and higher-order corrections beyond the CCSD(T) wave function are included in these calculations. The allylic [C5H5(2A2)] and dienylic [C5H5(2B1)] forms of cyclopentadienyl radical are considered: the ground state structure exists in the dienyl form and it is about 30 meV more stable than the allylic structure. Both structures are lying closely and are interconvertible along the normal mode of b2 in-plane vibration. The CCSDT/CBS predictions (in eV) for IE[C5H5+(3A1′)←C5H5(2B1)] = 8.443, IE[C5H5+(1A1)←C5H5(2B1)] = 8.634 and EA[C5H5–(1A1′)←C...

  • high level ab initio predictions for the Ionization Energy bond dissociation energies and heats of formation of nickel carbide nic and its cation nic
    Journal of Chemical Physics, 2010
    Co-Authors: Kaichung Lau, Yih Chung Chang, Xiaoyu Shi
    Abstract:

    The Ionization Energy (IE) of CoC and the 0 K bond dissociation energies (D0) and the heats of formation at 0 K (ΔH°f0) and 298 K (ΔH°f298) for CoC and CoC(+) are predicted by the wavefunction based coupled-cluster theory with single, double, triple and quadruple excitations (CCSDTQ) and complete basis set (CBS) approach. The CCSDTQ∕CBS calculations presented here involve the approximation to the CBS limit at the coupled cluster level up to full quadruple excitations along with the zero-point vibrational Energy, high-order correlation, core-valence (CV) electronic, spin-orbit coupling, and scalar relativistic effect corrections. The present calculations provide the correct symmetry, (1)Σ(+), for the ground state of CoC(+). The CCSDTQ∕CBS IE(CoC) = 7.740 eV is found in good agreement with the experimental IE value of 7.73467 ± 0.00007 eV, determined in a two-color laser photoion and pulsed field Ionization-photoelectron study. This work together with the previous experimental and theoretical investigations support the conclusion that the CCSDTQ∕CBS method is capable of providing reliable IE predictions for 3d-transition metal carbides, such as FeC, CoC, and NiC. Among the single-reference based coupled-cluster methods and multi-reference configuration interaction (MRCI) approach, the CCSDTQ and MRCI methods give the best predictions to the harmonic frequencies ωe (ωe (+)) = 956 (992) and 976 (1004) cm(-1) and the bond lengths re (re (+)) = 1.560 (1.528) and 1.550 (1.522) A, respectively, for CoC (CoC(+)) in comparison with the experimental values. The CCSDTQ∕CBS calculations give the prediction of D0(Co(+)-C) - D0(Co-C) = 0.175 eV, which is also consistent with the experimental determination of 0.14630 ± 0.00014 eV. The theoretical results show that the CV and valence-valence electronic correlations beyond CCSD(T) wavefunction and the relativistic effect make significant contributions to the calculated thermochemical properties of CoC∕CoC(+). For the experimental D0 and ΔH(o) f0 values of CoC∕CoC(+), which are not known experimentally, we recommend the following CCSDTQ∕CBS predictions: ΔH(o) f0(CoC) = 775.7 kJ∕mol and ΔH(o) f0(CoC(+)) = 1522.5 kJ∕mol, ΔH(o) f298(CoC) = 779.2 kJ∕mol and ΔH(o) 298(CoC(+)) = 1526.0 kJ∕mol.

  • high level ab initio predictions for the Ionization Energy bond dissociation energies and heats of formations of iron carbide fec and its cation fec
    Journal of Physical Chemistry A, 2009
    Co-Authors: Kaichung Lau, Yih Chung Chang, Chowshing Lam
    Abstract:

    The Ionization Energy IE of NiC and the 0 K bond dissociation energies D0 and heats of formation at 0 K H o f0 and 298 K H o f298 for NiC and NiC + are predicted by the wavefunction based CCSDTQFull/CBS approach and the multireference configuration interaction MRCI method with Davidson correction MRCI+Q. The CCSDTQFull/CBS calculations presented here involve the approximation to the complete basis set CBS limit at the coupled cluster level up to full quadruple excitations along with the zero-point vibrational Energy ZPVE, high-order correlation, core-valence electronic CV, spin-orbit coupling SO, and scalar relativistic effect SR corrections. The present calculations provide the correct symmetry predictions for the ground states of NiC and NiC + to be 1+ and 2+ , respectively. The CCSDTQFull/CBS IENiC =8.356 eV is found to compare favorably with the experimental IE value of 8.372 050.000 06 eV. The predicted IENiC value at the MRCI+Q /cc-pwCV5Z level, including the ZPVE, SO, and SR effects is 8.00 eV, which is 0.37 eV lower than the experimental value. This work together with the previous experimental and theoretical investigations supports the conclusion that the CCSDTQFull/CBS method is capable of providing reliable IE predictions for 3d-transition metal carbides, such as FeC and NiC. Furthermore, the CCSDTQFull/CBS

Xiaoqin Zeng - One of the best experts on this subject based on the ideXlab platform.

  • basal plane stacking fault energies of mg alloys a first principles study of metallic alloying effects
    Journal of Materials Science & Technology, 2018
    Co-Authors: Qing Dong, Zhe Luo, Hong Zhu, Leyun Wang, Tao Ying, Zhaohui Jin, Wenjiang Ding, Xiaoqin Zeng
    Abstract:

    Abstract Generalized stacking-fault energies (GSFEs) of basal-plane stacking faults I1 and I2 in Mg alloys have been studied based on first-principles calculations, where 43 alloying elements were considered. It is found that the most contributing features of alloying elements to GSFEs are bulk modulus, equilibrium volume, binding Energy, atomic radius and Ionization Energy. Both bulk modulus and Ionization Energy exhibit positive relationships with GSFEs, and the others show opposite relationships. Multiple regressions have been performed to offer a quantitative prediction for basal-plane GSFEs in Mg-X systems. GSFEs, alloying effects of elements and the prediction model established within this work may provide guidelines for new Mg alloys design with better ductility.

  • basal plane stacking fault energies of mg alloys a first principles study of metallic alloying effects
    Journal of Materials Science & Technology, 2018
    Co-Authors: Qing Dong, Leyun Wang, Tao Ying, Wenjiang Ding, Dejiang Li, Xiaoqin Zeng
    Abstract:

    Abstract Generalized stacking-fault energies (GSFEs) of basal-plane stacking faults I1 and I2 in Mg alloys have been studied based on first-principles calculations, where 43 alloying elements were considered. It is found that the most contributing features of alloying elements to GSFEs are bulk modulus, equilibrium volume, binding Energy, atomic radius and Ionization Energy. Both bulk modulus and Ionization Energy exhibit positive relationships with GSFEs, and the others show opposite relationships. Multiple regressions have been performed to offer a quantitative prediction for basal-plane GSFEs in Mg-X systems. GSFEs, alloying effects of elements and the prediction model established within this work may provide guidelines for new Mg alloys design with better ductility.

Uwe R Kortshagen - One of the best experts on this subject based on the ideXlab platform.

  • carrier transport in films of alkyl ligand terminated silicon nanocrystals
    Journal of Physical Chemistry C, 2014
    Co-Authors: Ting Chen, Brian Skinner, Wei Xie, B I Shklovskii, Uwe R Kortshagen
    Abstract:

    Silicon nanocrystals (Si NCs) have shown great promise for electroluminescent and photoluminescent applications. In order to optimize the properties of Si NC devices, however, electronic transport in Si NC films needs to be thoroughly understood. Here we present a systematic study of the temperature and electric field dependence of conductivity in films of alkyl-ligand-terminated Si NCs, which to date have shown the highest potential for device applications. Our measurements suggest that the conductivity is limited by the Ionization of rare NCs containing donor impurities. At low bias, this Ionization is thermally activated, with an Ionization Energy equal to twice the NC charging Energy. As the bias is increased, the Ionization Energy is reduced by the electric field, as determined by the Poole–Frenkel effect. At large bias and sufficiently low temperature, we observe cold Ionization of electrons from donor-containing NCs, with a characteristic tunneling length of about 1 nm. The temperature- and electri...

  • carrier transport in films of alkyl ligand terminated silicon nanocrystals
    arXiv: Mesoscale and Nanoscale Physics, 2014
    Co-Authors: Ting Chen, Brian Skinner, Wei Xie, B I Shklovskii, Uwe R Kortshagen
    Abstract:

    Silicon nanocrystals (Si NCs) have shown great promise for electroluminescent and photoluminescent applications. In order to optimize the properties of Si NC devices, however, electronic transport in Si NCs films needs to be thoroughly understood. Here we present a systematic study of the temperature and electric field dependence of conductivity in films of alkyl-ligand-terminated Si NCs, which to date have shown the highest potential for device applications. Our measurements suggest that the conductivity is limited by the Ionization of rare NCs containing donor impurities. At low bias, this Ionization is thermally activated, with an Ionization Energy equal to twice the NC charging Energy. As the bias is increased, the Ionization Energy is reduced by the electric field, as determined by the Poole-Frenkel effect. At large bias and sufficiently low temperature, we observe cold Ionization of electrons from donor-containing NCs, with a characteristic tunneling length of about 1 nm. The temperature- and electric-field-dependent conductance measurements presented here provide a systematic and comprehensive picture for electron transport in lightly doped nanocrystal films.