Synthesis and properties of Au-Fe3O4 and Ag-Fe3O4 heterodimeric nanoparticles

Monodisperse Au-Fe 3 O 4 heterodimeric nanoparticles (NPs) were prepared by injecting precursors into a hot reaction solution.The size of Au and Fe 3 O 4 particles can be controlled by changing the injection temperature.UV-Vis spectra show that the surface plasma resonance band of Au-Fe 3 O 4 heterodimeric NPs was evidently red-shifted compared with the resonance band of Au NPs of similar size.The as-prepared heterodimeric Au-Fe 3 O 4 NPs exhibited superparamagnetic properties at room temperature.The Ag-Fe 3 O 4 heterodimeric NPs were also prepared by this synthetic method simply using AgNO 3 as precursor instead of HAuCl 4.It is indicated that the reported method can be readily extended to the synthesis of other noble metal conjugated heterodimeric NPs.     

Superconductivity and critical fields in undoped and Sn-doped MoSr2YCu2O8−δ

Samples with nominal compositions MoSn_xSr₂YCu₂O_8−δ (0 ? x ? 0.075) were synthesized and their superconducting and magnetotransport properties were investigated. It was established that the optimum Sn-doping (x = 0.02 and 0.03) increases the T_c of the undoped MoSr₂YCu₂O_8−δ. The upper critical fields of the samples were determined using magnetization, susceptibility and resistivity measurements. It was established that the Sn-doping weakly affects the first and the intragrain second critical field of Mo-1212 but enhances the extrapolated to T = 0 (i.e. the intergrain) upper critical field. The observed phenomena were discussed on the basis of the Josephson-junction-arrays model. A phenomenological expression describing the temperature dependency of the susceptibility of Mo-1212 was found.     

Biomolecule-assisted hydrothermal synthesis of Sb2S3 and Bi2S3 nanocrystals and their elevated-temperature oxidation behavior for conversion into α-Sb2O4 and Bi2O3

We have developed a novel biomolecule-assisted hydrothermal method to prepare Sb₂S₃ and Bi₂S₃ nanocrystals with various sizes and shapes, in which cysteine combined with other sulfur source can exert the synergistic effect on products. The samples were characterized XRPD, TEM, HRTEM, FESEM, and PL techniques. First, we prepared a series of Sb₂S₃ and Bi₂S₃ nanocrystals by simply adjusting the composition of sulfur sources under hydrothermal conditions. Then, we studied the elevated-temperature oxidation behavior of these sulfides in air, which can lead to the formation of α-Sb₂O₄ and Bi₂O₃ samples at 600 °C for 3 h. The optical properties of the α-Sb₂O₄ and Bi₂O₃ samples were also discussed.     

Pionic Kα X-ray energy and linewidth IN 20Ne and 22Ne

We have measured the energies and linewidths of the pionic K_α X-rays for ²⁰Ne and ²²Ne using a natural liquid-neon target. The results are

     

5.

High-resolution infrared and theoretical study of the fundamental bands ν₂, ν₄ and ν₉ and the c-Coriolis interacting dyad ν₅, ν₁₄ of 1,3,4-thiadiazole     

F. Hegelund  R. Wugt Larsen  M.H. Palmer 《Journal of Molecular Spectroscopy》2008,248(2):161-167

The Fourier transform gas-phase IR spectrum of 1,3,4-thiadiazole, C₂H₂N₂S, has been recorded with a resolution of ca. 0.003 cm⁻¹ in the 800-1500 cm⁻¹ spectral region. Five fundamental bands ν₂(A₁; 1391.9 cm⁻¹), ν₄(A₁; 964.4 cm⁻¹), ν₅(A₁; 894.6 cm⁻¹), ν₉(B₁; 821.5 cm⁻¹), and ν₁₄(B₂; 898.4 cm⁻¹) have been analysed using the Watson model. Ground state rotational and quartic centrifugal distortion constants as well as upper state spectroscopic constants have been obtained from fits. The ν₄ and ν₉ bands are unperturbed while a strong c-Coriolis resonance perturbs the close-lying ν₅ and ν₁₄ bands. This dyad system has been analysed by a model including first and second order c-Coriolis resonance using the theoretically predicted Coriolis coupling constant . The ν₂ band is strongly perturbed by a local resonance, and we obtain a set of spectroscopic parameters using a model including second order a-Coriolis resonance with the inactive ν₁₀ + ν₁₄ band. Ground state rotational and quartic centrifugal distortion constants, anharmonic frequencies, and vibration-rotational α-constants predicted by quantum chemical calculations using a cc-pVTZ basis and B3LYP methodology, have been compared with the present experimental data, where there is generally good agreement.     

6.

Energy Landscape and Phase Competition of CsV₃Sb₅, CsV₆Sb₆ and TbMn₆Sn₆-Type Kagome Materials     

蔡光辉  姜昱韬  周辉  喻泽  蒋坤  石友国  孟胜  刘淼 《中国物理快报》2023,(11):103-121

Finding viable Kagome lattices is vital for materializing novel phenomena in quantum materials.In this study,we performed element substitutions on CsV₃Sb₅ with space group P 6/mmm,TbMn₆Sn₆ with space group P 6/mmm,and CsV₆Sb₆ with space group ■,as the parent compounds.Totally 4158 materials were obtained through element substitutions,and these materials were then calculated via density functional theory in high-throughput mode.Aft...     

7.

DFT calculation of core– and valence–shell electron excitation and ionization energies of 2,1,3-benzothiadiazole C₆H₄SN₂, 1,3,2,4-benzodithiadiazine C₆H₄S₂N₂, and 1,3,5,2,4-benzotrithiadiazepine C₆H₄S₃N₂     

Yuji Takahata  Delano P. Chong 《Journal of Electron Spectroscopy and Related Phenomena》2012

The vertical core– and valence–shell electron excitation and ionization energies of the three title molecules, 1–3, were calculated by density functional theory (DFT) using adequate functional for each type of processes and atoms under study. The inner shells treated were C1s, N1s, S1s, S2s, S2p. Molecular geometry was optimized by DFT B3LYP/6-311 + (d,p). The basis set of triple zeta plus polarization (TZP) Slater-type orbitals was employed for DFT calculations. The ΔSCF method was used to calculate ionization energies. The average absolute deviation (AAD) from experiment of 26 valence-electron ionization energies calculated by DFT for the three molecules 1–3 was 0.14 eV; while that of 24 calculated core-electron binding energies (CEBEs) from experiment was 0.4 eV. Selected core excitation energies were calculated by the multiplet approximation for the three molecules. The AAD of twelve calculated core excitation energies by the multiplet approximation that exclude S2s cases was 0.56 eV. Time-dependent DFT (TDDFT) was employed to calculate the excitation energies and corresponding oscillator strengths of core- and valence-electrons of the molecules. Some selected occupied core orbitals were used to calculate the core-excitation energies with the TDDFT (Sterner–Frozoni–Simone scheme). The core excitation energies thus calculated were in an average error of ca. 28 eV compared to observed values. They were shifted to the value calculated by the multiplet approximation. Convoluted spectra based upon the shifted energies and accompanying oscillator strengths reproduce low-energy region of observed spectra reasonably well, whereas they deviate from experiment in high-energy region. Reasonable agreement between theory and experiment was obtained for the valence electron excitations of the molecules.     

8.

Electronic and thermodynamic properties of α-Pu₂O₃     

Yong Lu  Yu Yang  Fawei Zheng  Ping Zhang 《Physics letters. A》2014

Based on density functional theory+U$\text{density functional theory}+U$ calculations and the quasi-annealing simulation method, we obtain the ground electronic state for α-Pu₂O₃ and present its phonon dispersion curves as well as various thermodynamic properties, which have seldom been theoretically studied because of the huge unit cell. We find that the Pu–O chemical bonding is weaker in α-Pu₂O₃ than in fluorite PuO₂, and subsequently a frequency gap appears between oxygen and plutonium vibration density of states. Based on the calculated Helmholtz free energies at different temperatures, we further study the reaction energies for Pu oxidation, PuO₂ reduction, and transformation between PuO₂ and α-Pu₂O₃. Our reaction energy results are in agreements with available experiment. And it is revealed that high temperature and insufficient oxygen environment are in favor of the formation of α-Pu₂O₃.     

9.

π⁺π⁺ and π⁺π^? Colliding in Noncommutative Space     

Jianhua Wang  Kang Li  Sayipjamal Dulat  Yi Yuan  Kai Ma 《International Journal of Theoretical Physics》2012,51(8):2639-2647

By studying the scattering process of scalar particle pion on the noncommutative scalar quantum electrodynamics, the non-commutative amendment of differential scattering cross-section is found, which is dependent of polar-angle and the results are significantly different from that in the commutative scalar quantum electrodynamics, particularly when cosθ∼±1. The non-commutativity of space is expected to be explored at around Λ_NC∼TeV.     

10.

High-resolution infrared and theoretical study of the fundamental bands ν₆, ν₇, ν₉ and ν₁₃ of 1,2,3-thiadiazole     

F. Hegelund  R. Wugt Larsen  P. Melec 《Journal of Molecular Spectroscopy》2008,250(1):8-19

The Fourier transform gas-phase IR spectrum of 1,2,3-thiadiazole, C₂H₂N₂S, has been recorded with a resolution of ca. 0.003 cm⁻¹ in the 700-1100 cm⁻¹ spectral region. Four fundamental bands ν₆(A^/; 1101.8 cm⁻¹), ν₇(A^/; 1038.8 cm⁻¹), ν₉(A^/, 858.9 cm⁻¹), and ν₁₃(A^//; 746.2 cm⁻¹) have been analyzed using the Watson model in A-reduction. Two additional bands, ν₈ (A^/; 894.6 cm⁻¹) and ν₁₂(A^//; 881.2 cm⁻¹) were assigned by their weak Q-branches. Ground state rotational and quartic centrifugal distortion constants as well as upper state spectroscopic constants have been obtained from fits. A number of weak global and local interactions are present in the bands. The resonances identified were qualitatively explained by Coriolis type perturbations with neighboring levels. Ground state rotational and quartic centrifugal distortion constants, anharmonic frequencies, and vibration-rotational α-constants predicted by quantum chemical calculations using a cc-pVTZ basis and B3LYP methodology, have been compared with the present experimental data, where there is generally good agreement.     

11.

Crystal structure and properties of Bi_{1 ? x} Ca _x FeO₃ and Bi_{1 ? x} Ca _x FeO_{1 ? x} Ti _x O₃ solid solutions     

I. O. Troyanchuk  D. V. Karpinsky  M. V. Bushinskii  O. Prokhnenko  M. Kopcevicz  R. Szymczak  J. Pietosa 《Journal of Experimental and Theoretical Physics》2008,107(1):83-89

Systems of solid solutions Bi_{1 − x} Ca _x FeO₃ (I) and Bi_{1 − x} CaxFeO_{1 − x} Ti _x O₃ (II) have been obtained and their properties have been studied using neutronography and M?ssbauer spectroscopy; magnetization and permittivity have been measured. It is shown that an increase in the concentration of calcium ions in system I for x > 0.2 changes rhombohedral distortions of a unit cell (space group R3c) to tetragonal distortions (space group I4/mcm), while rhombohedral distortions in system II for x > 0.2 are replaced by orthorhombic distortions (space group Pnma). Analysis of the crystal structure has revealed strong anisotropy in vibrations of Bi and O ions in system I compounds. Systems I and II are characterized by G-type antiferromagnetic ordering of magnetic moments. In system II, spontaneous magnetization associated with the Dzyaloshinskii-Moriya interaction has been detected. According to M?ssbauer spectroscopy data, iron ions in compounds I and II are in the trivalent state and charge compensation occurs due to the formation of oxygen vacancies. The permittivity increases with the calcium concentration. Original Russian Text ? I.O. Troyanchuk, D.V. Karpinsky, M.V. Bushinskii, O. Prokhnenko, M. Kopcevicz, R. Szymczak, J. Pietosa, 2008, published in Zhurnal éksperimental’noĭ i Teoreticheskoĭ Fiziki, 2008, Vol. 134, No. 1, pp. 105–112.     

12.

D^?→Dπ and D^?→Dγ decays: axial coupling and magnetic moment of D^? meson     

Damir Be?irevi?  Benjamin Haas 《The European Physical Journal C - Particles and Fields》2011,71(8):1734

The axial coupling and the magnetic moment of D ^∗-meson or, more specifically, the couplings g_D^*Dpg_{D^{\ast}D\pi} and g_D^*Dgg_{D^{\ast}D\gamma }, encode the non-perturbative QCD effects describing the decays D ^∗→Dπ and D ^∗→Dγ. We compute these quantities by means of lattice QCD with N _f=2 dynamical quarks, by employing the Wilson (“clover”) action. On our finer lattice (a≈0.065 fm) we obtain g_D^*Dp⁺=20±2g_{D^{\ast}D\pi^{+}}=20\pm2, and g_{D^*0 D⁰g}=2.0±0.6 GeV^-1g_{D^{\ast0} D^{0}\gamma}=2.0\pm 0.6~{\rm GeV}^{-1}. This is the first determination of g_{D^*0 D⁰g}g_{D^{\ast0} D^{0}\gamma} on the lattice. We also provide a short phenomenological discussion and the comparison of our result with experiment and with the results quoted in the literature.     

13.

Renner-Teller and Spin-Orbit Interactions between the ÃA₁ and the X?B₁ States of NH₂: The Stretch-Bender Approach     

Alexander Alijah  Geoffrey Duxbury 《Journal of Molecular Spectroscopy》2002,211(1):7-15

The stretch-bender model, developed originally to describe the effects of stretch-bend interactions and Renner-Teller coupling in symmetrical triatomic molecules, has been extended to incorporate the effects of spin-orbit interaction and of overall rotation. A comparison is made between the treatment of spin-orbit interaction and of overall rotation in our model and in the MORBID approach of P. Jensen, M. Brumm, W. P. Kraemer, and P. R. Bunker (J. Mol. Spectrosc.171, 31-57 (1995)).     

14.

FTIR spectra and rovibrational analysis of the ν₁₁ band of trans-ClHCCHF and ν₁₀ of trans-ClHCCDF     

Alberto Gambi  Paolo Stoppa 《Journal of Molecular Spectroscopy》2008,252(1):47-51

High-resolution Fourier transform infrared spectra of natural trans-ClHCCHF and of its isotopologue trans-ClHCCDF have been recorded in the region between 700 and 1150 cm⁻¹ with the purpose to analyze the ν₁₁ fundamental of the main species and the ν₁₀ of its deuterated compound. Both bands, of symmetry species A″, present c-type envelope absorptions. Beside the expected features, the K structure of the P(J), Q(J), and R(J) manifolds was resolved and identified; the assignment of the rovibrational transitions was extended up to J = 92 and K_a = 13 for the trans-³⁵ClHCCHF and up to J = 86 and K_a = 10 for trans-³⁵ClHCCDF. More than 2900 and 2700 lines for the main and deuterated species, respectively, were analyzed by a least-squares procedure and reliable spectroscopic molecular parameters were determined for both isotopologues.     

15.

The ν₄ and ν₂ + ν₅ high resolution infrared bands of FClO₃ and FClO₃     

E. Cané  K. Burczyk 《Journal of Molecular Spectroscopy》2008,247(1):57-63

The high resolution infrared spectra of monoisotopic F³⁵Cl¹⁸O₃ and F³⁷Cl¹⁸O₃ have been studied in the region of the ν₄ fundamentals, centered at 1278.3 and 1263.3 cm⁻¹, respectively. Large perturbations are observed in both bands due to a Fermi type anharmonic resonance with the ν₂ + ν₅ combination bands, centered at 1270.7 cm⁻¹ in F³⁵Cl¹⁸O₃ and 1257.3 cm⁻¹ in F³⁷Cl¹⁸O₃. In particular, they affect the kl > 0 levels of the v₄ = 1 and v₂ = v₅ = 1 states which cross at kl ? 18 in F³⁵Cl¹⁸O₃ and kl ? 3 in F³⁷Cl¹⁸O₃, due to the opposite values of and . The Δl = Δk = ±2 and Δl = 0, Δk = ±3 essential resonances are also effective in the excited states of the dyad in F³⁵Cl¹⁸O₃, while in F³⁷Cl¹⁸O₃ only the Δl = Δk = ±2 one is active. In the spectrum of F³⁵Cl¹⁸O₃ 3423 transitions have been assigned, 10% of them belonging to ν₂ + ν₅. The rovibrational parameters and the interaction constants between the v₄ = 1 and v₂ = v₅ = 1 levels have been obtained. The depertubed band origins of ν₄ and ν₂ + ν₅ are 1277.310567(165) and 1271.753733(195) cm⁻¹, respectively, and the anharmonic resonance constant is 2.804416(153) cm⁻¹. For F³⁷Cl¹⁸O₃, 3022 transitions have been assigned, 38% belonging to the ν₂ + ν₅ combination band. The depertubed band origins are 1260.856338(123) and 1259.872338(134) cm⁻¹, for ν₄and ν₂ + ν₅ and the constant is 2.9350669(405) cm⁻¹. The equilibrium geometry of perchloryl fluoride, r_e (ClO) = 139.7(3) pm, r_e (ClF) = 161.0(5) pm, and α_e (OClO) = 115.7(4) degree, has been determined using the A_e and B_e equilibrium constants of the four symmetric isotopologues of perchloryl fluoride, F^35/37Cl¹⁶O₃ and F^35/37Cl¹⁸O₃.     

16.

Solvothermal synthesis and characterization of α-Fe₂O₃ nanodiscs and Mn₃O₄ nanoparticles with 1,10-phenanthroline     

Robabeh Mehdizadeh  Lotf Ali SaghatforoushSoheila Sanati 《Superlattices and Microstructures》2012

α-Fe₂O₃ nanodiscs and Mn₃O₄ nanoparticles have been prepared by the 1,10-phenanthroline as complexing agent in the presence of sodium hydroxide under hydrothermal conditions. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared (FT-IR) spectra. The average diameter of α-Fe₂O₃ nanodiscs is of 2 μm. In the case of Mn₃O₄ sample, the Mn₃O₄ crystallites are nanoparticles with an average size of 34 nm. A formation mechanism for the α-Fe₂O₃ and Mn₃O₄ nanomaterials was proposed.     

17.

Porous silicon based β-FeSi₂ and photoluminescence     

H. T. Chen  X. L. Wu  Y. Y. Zhang  W. N. Su 《Applied Physics A: Materials Science & Processing》2009,97(3):725-728

Highly-pure iron powder was covered on porous silicon for fabricating semiconducting β-FeSi₂ structures. X-ray diffraction and Raman scattering results confirm the formation of pure-phase β-FeSi₂ after high-temperature annealing at 1100°C and then long-time persistence at 900°C. Scanning electron microscope observations reveal that large-size (>μm) β-FeSi₂ grains mainly form in the pores of porous silicon and some nanocrystals grow on local surfaces. The temperature-dependent photoluminescence spectra disclose that the observed ∼1.54 μm emission arises from free exciton recombination, which is confirmed via the activation energy (0.25 eV) measurement. Our method provides a way to synthesize single-phase β-FeSi₂ materials.     

18.

Resonance-enhanced multiphoton ionization spectroscopy of CH₃ and CD₃. Two-photon absorption selection rules and rotational line strengths of the ν₃- and ν₄-active vibronic transitions     

Kuo-mei Chen 《Journal of Molecular Spectroscopy》2004,224(2):145-150

To explore the possibility of K-level resolved, 2+1 resonance-enhanced multiphoton ionization (REMPI) processes of the methyl radical, the two-photon absorption selection rules and rotational line strengths of the 3₀¹ and 4₀¹ vibronic bands of the transition (n=3 or 4) were reported. Stringent selection rules, which were imposed upon these two-photon transitions, are the initial K″=3p (p=0,1,2,…), ΔK=±2, ΔU=±3, and ΔN=0,±1,±2 (O, P, Q, R, and S branches). The previously assigned 2₂² vibronic band of the methyl radical should be studied by the REMPI with a better spectral resolution and analyzed by the newly derived two-photon absorption selection rules and rotational line strength formulas.     

19.

Electronic and crystal structure of α- and β-CeIr₂Si₂     

M. Mihalik  M. Diviš  V. Sechovský 《Physica B: Condensed Matter》2009,404(19):3191-3194

We present the results of XRD, magnetization, resistivity and specific heat measurements of CeIr₂Si₂ single crystals for both, the low-temperature α-phase and the high-temperature β-phase, respectively. The α-phase adopts the tetragonal ThCr₂Si₂-type whereas the β-phase forms in the CaBe₂Ge₂-type structure. Both the phases remain paramagnetic down to low temperatures, nevertheless both, the magnetization and resistivity exhibit pronounced anisotropy in the whole temperature range of measurements (2-300 K). Results of fitting the temperature dependence of the susceptibility within the interconfiguration-fluctuation model point to the Ce valence fluctuating between 3+ and 4+. The α-phase behaves as a Fermi-liquid (FL) at low temperatures whereas the β-phase exhibits non-Fermi-liquid (NFL) features. The results are discussed in context of other similar polymorphic compounds.     

20.

High resolution Fourier transform infrared spectra and analysis of the ν₁₄, ν₁₅ and ν₁₆ bands of azetidine     

Taras Zaporozan 《Journal of Molecular Spectroscopy》2010,264(2):105-110

Rotationally resolved vibrational spectra of the three lowest frequency bands of the four-membered heterocycle azetidine (c-C₃H₆NH) have been collected with a resolution of 0.00096 cm⁻¹ using the far infrared beamline at the Canadian Light Source synchrotron. The modes observed correspond principally to motions best described as: β-CH₂ rock (ν₁₄) at 736.701310(7) cm⁻¹, ring deformation (ν₁₅) at 648.116041(8) cm⁻¹, and the ring puckering mode (ν₁₆) at 207.727053(9) cm⁻¹. A global fit of 14 276 rovibrational transitions from the three bands provided an accurate set of ground state spectroscopic constants as well as excited state parameters for each of the three vibrational modes. The ground state structure was determined to be that of the puckered conformer having the NH bond in an equatorial arrangement.     

20Ne	22Ne
Neenergy (keV)	239.12±0.14	230.49±0.88
width (keV)	15.43±0.41	12.65±3.51

High-resolution infrared and theoretical study of the fundamental bands ν2, ν4 and ν9 and the c-Coriolis interacting dyad ν5, ν14 of 1,3,4-thiadiazole

The Fourier transform gas-phase IR spectrum of 1,3,4-thiadiazole, C₂H₂N₂S, has been recorded with a resolution of ca. 0.003 cm⁻¹ in the 800-1500 cm⁻¹ spectral region. Five fundamental bands ν₂(A₁; 1391.9 cm⁻¹), ν₄(A₁; 964.4 cm⁻¹), ν₅(A₁; 894.6 cm⁻¹), ν₉(B₁; 821.5 cm⁻¹), and ν₁₄(B₂; 898.4 cm⁻¹) have been analysed using the Watson model. Ground state rotational and quartic centrifugal distortion constants as well as upper state spectroscopic constants have been obtained from fits. The ν₄ and ν₉ bands are unperturbed while a strong c-Coriolis resonance perturbs the close-lying ν₅ and ν₁₄ bands. This dyad system has been analysed by a model including first and second order c-Coriolis resonance using the theoretically predicted Coriolis coupling constant . The ν₂ band is strongly perturbed by a local resonance, and we obtain a set of spectroscopic parameters using a model including second order a-Coriolis resonance with the inactive ν₁₀ + ν₁₄ band. Ground state rotational and quartic centrifugal distortion constants, anharmonic frequencies, and vibration-rotational α-constants predicted by quantum chemical calculations using a cc-pVTZ basis and B3LYP methodology, have been compared with the present experimental data, where there is generally good agreement.     

Energy Landscape and Phase Competition of CsV3Sb5, CsV6Sb6 and TbMn6Sn6-Type Kagome Materials

Finding viable Kagome lattices is vital for materializing novel phenomena in quantum materials.In this study,we performed element substitutions on CsV₃Sb₅ with space group P 6/mmm,TbMn₆Sn₆ with space group P 6/mmm,and CsV₆Sb₆ with space group ■,as the parent compounds.Totally 4158 materials were obtained through element substitutions,and these materials were then calculated via density functional theory in high-throughput mode.Aft...     

DFT calculation of core– and valence–shell electron excitation and ionization energies of 2,1,3-benzothiadiazole C6H4SN2, 1,3,2,4-benzodithiadiazine C6H4S2N2, and 1,3,5,2,4-benzotrithiadiazepine C6H4S3N2

The vertical core– and valence–shell electron excitation and ionization energies of the three title molecules, 1–3, were calculated by density functional theory (DFT) using adequate functional for each type of processes and atoms under study. The inner shells treated were C1s, N1s, S1s, S2s, S2p. Molecular geometry was optimized by DFT B3LYP/6-311 + (d,p). The basis set of triple zeta plus polarization (TZP) Slater-type orbitals was employed for DFT calculations. The ΔSCF method was used to calculate ionization energies. The average absolute deviation (AAD) from experiment of 26 valence-electron ionization energies calculated by DFT for the three molecules 1–3 was 0.14 eV; while that of 24 calculated core-electron binding energies (CEBEs) from experiment was 0.4 eV. Selected core excitation energies were calculated by the multiplet approximation for the three molecules. The AAD of twelve calculated core excitation energies by the multiplet approximation that exclude S2s cases was 0.56 eV. Time-dependent DFT (TDDFT) was employed to calculate the excitation energies and corresponding oscillator strengths of core- and valence-electrons of the molecules. Some selected occupied core orbitals were used to calculate the core-excitation energies with the TDDFT (Sterner–Frozoni–Simone scheme). The core excitation energies thus calculated were in an average error of ca. 28 eV compared to observed values. They were shifted to the value calculated by the multiplet approximation. Convoluted spectra based upon the shifted energies and accompanying oscillator strengths reproduce low-energy region of observed spectra reasonably well, whereas they deviate from experiment in high-energy region. Reasonable agreement between theory and experiment was obtained for the valence electron excitations of the molecules.     

Electronic and thermodynamic properties of α-Pu2O3

Based on density functional theory+U$\text{density functional theory}+U$ calculations and the quasi-annealing simulation method, we obtain the ground electronic state for α-Pu₂O₃ and present its phonon dispersion curves as well as various thermodynamic properties, which have seldom been theoretically studied because of the huge unit cell. We find that the Pu–O chemical bonding is weaker in α-Pu₂O₃ than in fluorite PuO₂, and subsequently a frequency gap appears between oxygen and plutonium vibration density of states. Based on the calculated Helmholtz free energies at different temperatures, we further study the reaction energies for Pu oxidation, PuO₂ reduction, and transformation between PuO₂ and α-Pu₂O₃. Our reaction energy results are in agreements with available experiment. And it is revealed that high temperature and insufficient oxygen environment are in favor of the formation of α-Pu₂O₃.     

π+π+ and π+π? Colliding in Noncommutative Space

By studying the scattering process of scalar particle pion on the noncommutative scalar quantum electrodynamics, the non-commutative amendment of differential scattering cross-section is found, which is dependent of polar-angle and the results are significantly different from that in the commutative scalar quantum electrodynamics, particularly when cosθ∼±1. The non-commutativity of space is expected to be explored at around Λ_NC∼TeV.     

High-resolution infrared and theoretical study of the fundamental bands ν6, ν7, ν9 and ν13 of 1,2,3-thiadiazole

The Fourier transform gas-phase IR spectrum of 1,2,3-thiadiazole, C₂H₂N₂S, has been recorded with a resolution of ca. 0.003 cm⁻¹ in the 700-1100 cm⁻¹ spectral region. Four fundamental bands ν₆(A^/; 1101.8 cm⁻¹), ν₇(A^/; 1038.8 cm⁻¹), ν₉(A^/, 858.9 cm⁻¹), and ν₁₃(A^//; 746.2 cm⁻¹) have been analyzed using the Watson model in A-reduction. Two additional bands, ν₈ (A^/; 894.6 cm⁻¹) and ν₁₂(A^//; 881.2 cm⁻¹) were assigned by their weak Q-branches. Ground state rotational and quartic centrifugal distortion constants as well as upper state spectroscopic constants have been obtained from fits. A number of weak global and local interactions are present in the bands. The resonances identified were qualitatively explained by Coriolis type perturbations with neighboring levels. Ground state rotational and quartic centrifugal distortion constants, anharmonic frequencies, and vibration-rotational α-constants predicted by quantum chemical calculations using a cc-pVTZ basis and B3LYP methodology, have been compared with the present experimental data, where there is generally good agreement.     

Crystal structure and properties of Bi1 ? x Ca x FeO3 and Bi1 ? x Ca x FeO1 ? x Ti x O3 solid solutions

Systems of solid solutions Bi_{1 − x} Ca _x FeO₃ (I) and Bi_{1 − x} CaxFeO_{1 − x} Ti _x O₃ (II) have been obtained and their properties have been studied using neutronography and M?ssbauer spectroscopy; magnetization and permittivity have been measured. It is shown that an increase in the concentration of calcium ions in system I for x > 0.2 changes rhombohedral distortions of a unit cell (space group R3c) to tetragonal distortions (space group I4/mcm), while rhombohedral distortions in system II for x > 0.2 are replaced by orthorhombic distortions (space group Pnma). Analysis of the crystal structure has revealed strong anisotropy in vibrations of Bi and O ions in system I compounds. Systems I and II are characterized by G-type antiferromagnetic ordering of magnetic moments. In system II, spontaneous magnetization associated with the Dzyaloshinskii-Moriya interaction has been detected. According to M?ssbauer spectroscopy data, iron ions in compounds I and II are in the trivalent state and charge compensation occurs due to the formation of oxygen vacancies. The permittivity increases with the calcium concentration. Original Russian Text ? I.O. Troyanchuk, D.V. Karpinsky, M.V. Bushinskii, O. Prokhnenko, M. Kopcevicz, R. Szymczak, J. Pietosa, 2008, published in Zhurnal éksperimental’noĭ i Teoreticheskoĭ Fiziki, 2008, Vol. 134, No. 1, pp. 105–112.     

D?→Dπ and D?→Dγ decays: axial coupling and magnetic moment of D? meson

The axial coupling and the magnetic moment of D ^∗-meson or, more specifically, the couplings g_D^*Dpg_{D^{\ast}D\pi} and g_D^*Dgg_{D^{\ast}D\gamma }, encode the non-perturbative QCD effects describing the decays D ^∗→Dπ and D ^∗→Dγ. We compute these quantities by means of lattice QCD with N _f=2 dynamical quarks, by employing the Wilson (“clover”) action. On our finer lattice (a≈0.065 fm) we obtain g_D^*Dp⁺=20±2g_{D^{\ast}D\pi^{+}}=20\pm2, and g_{D^*0 D⁰g}=2.0±0.6 GeV^-1g_{D^{\ast0} D^{0}\gamma}=2.0\pm 0.6~{\rm GeV}^{-1}. This is the first determination of g_{D^*0 D⁰g}g_{D^{\ast0} D^{0}\gamma} on the lattice. We also provide a short phenomenological discussion and the comparison of our result with experiment and with the results quoted in the literature.     

Renner-Teller and Spin-Orbit Interactions between the ÃA1 and the X?B1 States of NH2: The Stretch-Bender Approach

The stretch-bender model, developed originally to describe the effects of stretch-bend interactions and Renner-Teller coupling in symmetrical triatomic molecules, has been extended to incorporate the effects of spin-orbit interaction and of overall rotation. A comparison is made between the treatment of spin-orbit interaction and of overall rotation in our model and in the MORBID approach of P. Jensen, M. Brumm, W. P. Kraemer, and P. R. Bunker (J. Mol. Spectrosc.171, 31-57 (1995)).     

FTIR spectra and rovibrational analysis of the ν11 band of trans-ClHCCHF and ν10 of trans-ClHCCDF

High-resolution Fourier transform infrared spectra of natural trans-ClHCCHF and of its isotopologue trans-ClHCCDF have been recorded in the region between 700 and 1150 cm⁻¹ with the purpose to analyze the ν₁₁ fundamental of the main species and the ν₁₀ of its deuterated compound. Both bands, of symmetry species A″, present c-type envelope absorptions. Beside the expected features, the K structure of the P(J), Q(J), and R(J) manifolds was resolved and identified; the assignment of the rovibrational transitions was extended up to J = 92 and K_a = 13 for the trans-³⁵ClHCCHF and up to J = 86 and K_a = 10 for trans-³⁵ClHCCDF. More than 2900 and 2700 lines for the main and deuterated species, respectively, were analyzed by a least-squares procedure and reliable spectroscopic molecular parameters were determined for both isotopologues.     

The ν4 and ν2 + ν5 high resolution infrared bands of FClO3 and FClO3

The high resolution infrared spectra of monoisotopic F³⁵Cl¹⁸O₃ and F³⁷Cl¹⁸O₃ have been studied in the region of the ν₄ fundamentals, centered at 1278.3 and 1263.3 cm⁻¹, respectively. Large perturbations are observed in both bands due to a Fermi type anharmonic resonance with the ν₂ + ν₅ combination bands, centered at 1270.7 cm⁻¹ in F³⁵Cl¹⁸O₃ and 1257.3 cm⁻¹ in F³⁷Cl¹⁸O₃. In particular, they affect the kl > 0 levels of the v₄ = 1 and v₂ = v₅ = 1 states which cross at kl ? 18 in F³⁵Cl¹⁸O₃ and kl ? 3 in F³⁷Cl¹⁸O₃, due to the opposite values of and . The Δl = Δk = ±2 and Δl = 0, Δk = ±3 essential resonances are also effective in the excited states of the dyad in F³⁵Cl¹⁸O₃, while in F³⁷Cl¹⁸O₃ only the Δl = Δk = ±2 one is active. In the spectrum of F³⁵Cl¹⁸O₃ 3423 transitions have been assigned, 10% of them belonging to ν₂ + ν₅. The rovibrational parameters and the interaction constants between the v₄ = 1 and v₂ = v₅ = 1 levels have been obtained. The depertubed band origins of ν₄ and ν₂ + ν₅ are 1277.310567(165) and 1271.753733(195) cm⁻¹, respectively, and the anharmonic resonance constant is 2.804416(153) cm⁻¹. For F³⁷Cl¹⁸O₃, 3022 transitions have been assigned, 38% belonging to the ν₂ + ν₅ combination band. The depertubed band origins are 1260.856338(123) and 1259.872338(134) cm⁻¹, for ν₄and ν₂ + ν₅ and the constant is 2.9350669(405) cm⁻¹. The equilibrium geometry of perchloryl fluoride, r_e (ClO) = 139.7(3) pm, r_e (ClF) = 161.0(5) pm, and α_e (OClO) = 115.7(4) degree, has been determined using the A_e and B_e equilibrium constants of the four symmetric isotopologues of perchloryl fluoride, F^35/37Cl¹⁶O₃ and F^35/37Cl¹⁸O₃.     

Solvothermal synthesis and characterization of α-Fe2O3 nanodiscs and Mn3O4 nanoparticles with 1,10-phenanthroline

α-Fe₂O₃ nanodiscs and Mn₃O₄ nanoparticles have been prepared by the 1,10-phenanthroline as complexing agent in the presence of sodium hydroxide under hydrothermal conditions. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared (FT-IR) spectra. The average diameter of α-Fe₂O₃ nanodiscs is of 2 μm. In the case of Mn₃O₄ sample, the Mn₃O₄ crystallites are nanoparticles with an average size of 34 nm. A formation mechanism for the α-Fe₂O₃ and Mn₃O₄ nanomaterials was proposed.     

Porous silicon based β-FeSi2 and photoluminescence

Highly-pure iron powder was covered on porous silicon for fabricating semiconducting β-FeSi₂ structures. X-ray diffraction and Raman scattering results confirm the formation of pure-phase β-FeSi₂ after high-temperature annealing at 1100°C and then long-time persistence at 900°C. Scanning electron microscope observations reveal that large-size (>μm) β-FeSi₂ grains mainly form in the pores of porous silicon and some nanocrystals grow on local surfaces. The temperature-dependent photoluminescence spectra disclose that the observed ∼1.54 μm emission arises from free exciton recombination, which is confirmed via the activation energy (0.25 eV) measurement. Our method provides a way to synthesize single-phase β-FeSi₂ materials.     

Resonance-enhanced multiphoton ionization spectroscopy of CH3 and CD3. Two-photon absorption selection rules and rotational line strengths of the ν3- and ν4-active vibronic transitions

To explore the possibility of K-level resolved, 2+1 resonance-enhanced multiphoton ionization (REMPI) processes of the methyl radical, the two-photon absorption selection rules and rotational line strengths of the 3₀¹ and 4₀¹ vibronic bands of the transition (n=3 or 4) were reported. Stringent selection rules, which were imposed upon these two-photon transitions, are the initial K″=3p (p=0,1,2,…), ΔK=±2, ΔU=±3, and ΔN=0,±1,±2 (O, P, Q, R, and S branches). The previously assigned 2₂² vibronic band of the methyl radical should be studied by the REMPI with a better spectral resolution and analyzed by the newly derived two-photon absorption selection rules and rotational line strength formulas.     

Electronic and crystal structure of α- and β-CeIr2Si2

We present the results of XRD, magnetization, resistivity and specific heat measurements of CeIr₂Si₂ single crystals for both, the low-temperature α-phase and the high-temperature β-phase, respectively. The α-phase adopts the tetragonal ThCr₂Si₂-type whereas the β-phase forms in the CaBe₂Ge₂-type structure. Both the phases remain paramagnetic down to low temperatures, nevertheless both, the magnetization and resistivity exhibit pronounced anisotropy in the whole temperature range of measurements (2-300 K). Results of fitting the temperature dependence of the susceptibility within the interconfiguration-fluctuation model point to the Ce valence fluctuating between 3+ and 4+. The α-phase behaves as a Fermi-liquid (FL) at low temperatures whereas the β-phase exhibits non-Fermi-liquid (NFL) features. The results are discussed in context of other similar polymorphic compounds.     

High resolution Fourier transform infrared spectra and analysis of the ν14, ν15 and ν16 bands of azetidine

Rotationally resolved vibrational spectra of the three lowest frequency bands of the four-membered heterocycle azetidine (c-C₃H₆NH) have been collected with a resolution of 0.00096 cm⁻¹ using the far infrared beamline at the Canadian Light Source synchrotron. The modes observed correspond principally to motions best described as: β-CH₂ rock (ν₁₄) at 736.701310(7) cm⁻¹, ring deformation (ν₁₅) at 648.116041(8) cm⁻¹, and the ring puckering mode (ν₁₆) at 207.727053(9) cm⁻¹. A global fit of 14 276 rovibrational transitions from the three bands provided an accurate set of ground state spectroscopic constants as well as excited state parameters for each of the three vibrational modes. The ground state structure was determined to be that of the puckered conformer having the NH bond in an equatorial arrangement.