Extraction of the asymptotic normalization coefficient for the first 2+ level of 16O from the analysis of α12C scattering on the basis of analytical approach

The information about the nuclear vertex constant G ₁₂ for the ¹⁶O(6.917 MeV, 2⁺) ? α + ¹²C vertex and the related asymptotic normalization coefficient C ¹² of the wave function of the first excited state of the ¹⁶O nucleus with the angular momentum J = 2 and positive parity is extracted on the basis of the phase analysis data for the α¹²C scattering using the N/D equations, with allowance for the Coulomb interaction effects.     

Absolute Line Intensities in the 2ν3Band of16O12C32S

The strengths of 100 lines in the 2ν₃band of¹⁶O¹²C³²S have been measured at high resolution in the spectral range 4069–4118 cm⁻¹, using a tunable difference-frequency laser spectrometer. These intensities were obtained by fitting Voigt profiles to the measured shapes of the lines. The vibrational transition moment [(2.141 ± 0.020) × 10⁻²D] and the absolute intensity (16.19 ± 0.24 cm⁻²atm⁻¹at 296 K) of the 2ν₃band of¹⁶O¹²C³²S are determined from these linestrength measurements.     

Astrophysical S-factor of the 12C（α,γ） 16O reaction at solar energies

The astrophysical S-factor of the 4He＋12C radiative capture is calculated in the potential model at the energy range 0.1-2.0 MeV. Radiative capture 12C（α,γ） 16O is extremely relevant for the fate of massive stars and determines if the remnant of a supernova explosion becomes a black hole or a neutron star. Because this reaction occurs at low energies, the experimental measurements are very difficult and perhaps impossible. In this paper, radiative capture of the 12C（α,γ） 16O reaction at very low energies is taken as a case study. In comparison with other theoretical methods and available experimental data, good agreement is achieved for the astrophysical S-factor of this process.     

Polarization effect on the spin symmetry for anti-Lambda spectrum in ^16O＋∧ system

^The polarization effect on the spin symmetry for anti-Lambda spectrum in 16 O＋Λ system has been studied in relativistic mean-field theory.The PK1 effective interaction is used for nucleon-meson couplings and G-parity symmetry with a reduction factor ξ = 0.3 is adopted for anti-Lambda-meson couplings.The energy differences between spin doublets in the anti-Lambda spectrum are around 0.10-0.73 MeV for p Λ state.The dominant components of the Dirac spinor for the anti-Lambda spin doublets are found to be near identical.It indicates that the spin symmetry is still well-conserved against the polarization effect from the valence antiLambda hyperon,which leads to a highly compressed cold nucleus with the central density up to 2 - 3 times of saturated density.     

The characteristics of O＋HD （v = 0, j = 0） reaction dynamics

The analytical potential energy function of HDO is constructed at first using the many-body expansion method.The reaction dynamics of O+HD(v = 0,j = 0) in five product channels are all studied by quasi-classical trajectory(QCT) method.The results show that the long-lived complex compound HDO is the dominant product at low collision energy.With increasing collision energy,O+HD → OH+D and O+HD → OD+H exchange reactions will occur with remarkable characteristics,such as near threshold energies,different reaction probabilities,and different reaction cross sections,implying the isotopic effect between H and D.With further increasing collision energy(e.g.,up to 502.08 kJ/mol),O+HD → O+H+D will occur and induce the complete dissociation into single O,H,and D atoms.     

Fourier spectroscopy of the Asundi system (a′3Σ+-a3Π) of 13C16O

The Asundi system (a′³Σ⁺-a³Π) of ¹³C¹⁶O has been studied between 3500 and 12 000 cm⁻¹ by high-resolution Fourier transform spectroscopy. The 10 bands, 0-0, 0−1, 1−0, 1−1, 1−2, 2−0, 2−1, 3−0, 4−0, and 4−2, were analyzed taking into account the strong perturbations appearing in the a′³Σ⁺ (v = 0,…,4) levels. Accurate perturbation parameters were obtained for all interacting states.     

Exotic interactions between solitons of the （2＋1）-dimensional asymmetric Nizhnik-Novikov-Veselov system

Starting from the extended tanh-function method (ETM) based on the mapping method, the variable separation solutions of the (2+1)-dimensional asymmetric Nizhnik--Novikov--Veselov (ANNV) system are derived. By further study, we find that these variable separation solutions are seemingly independent of but actually dependent on each other. Based on the variable separation solution and by choosing appropriate functions, some novel and interesting interactions between special solitons, such as bell-like compacton, peakon-like compacton and compacton-like semi-foldon, are investigated.     

Influence of Si^4＋ substitution on the temperature-dependent characteristics of YaAl5O12：Ce

A series of aAl5O12：Ce （YAG：Ce） phosphors doped with different Si4＋ concentrations is prepared by solid-state reaction. The temperature dependent characteristics of luminescent spectrum and decay time of Ce3＋ are investigated. With Si4＋ doped, the emission spectrum shows a blue shift clue to a decrease of the splitting of 5d levels of Ce3＋ ion. The thermal stability is greatly improved by adding Si4＋ because the activation energy AE increases from 0.1836 eV to 0.2401 eV. The study of the decay times against temperature for various doping concentrations of Si4＋ shows that the calculated nonradiative decay rate is affected by Si4＋ substitution. The results are explained by the configurational coordinate diagram.     

Intense up-conversion emissions of yb3＋/Dy3＋ co-doped A12O3 nanopowders prepared by non-aqueous sol-gel method＊

Yb 3+ /Dy 3+ co-doped Al2O3 nanopowders have been prepared by the non-aqueous sol-gel method and their up- conversion photoluminescence spectra are measured under excitation by a 980-nm semiconductor laser. The results show that there are comparatively abundant spectra of up-conversion emissions centered at 378, 408, 527 and 543, and 663 nm, corresponding to4G9/2 → 6H13/2,4G9/2→6H11/2 ,4I15/2 →6H13/2 , and 4F9/2 → 6H11/2 transitions of Dy 3+ , respectively. Two-photon and three-photon processes are involved in ultraviolet, violet, green, and red up-conversion emissions. The energy transition between Yb3+ and Dy3+ is discussed.     

Low-Energy Direct Capture in the ^12C（α, γ）^16O Reaction

The spectra of light nuclei provide the first test of nuclear interaction models. The reaction amount determines the relative abundance of most elements in red giant stars, neutron stars, and black holes. Due to the fact that this reaction occurs at low energies, the experimental measurement is very difficult and perhaps impossible. In this work, the radiative capture of the ^12C（α, γ）^16O reaction at very low-energies is taken as a case study. Using the M3Y potential we calculate the astrophysical Factor for transition E1 and E2. In comparison with other theoretical methods and available recent experimental data, excellent agreement is achieved for the astrophysical S-factor of this process.     

Theoretical prediction of the optimal conditions for observing the stereodynamical vector properties of the C（3P）＋OH （X2∏）→CO（X1S＋）＋H（2S） reaction

The best optimal initial reactant state and collision energy for observing the stereodynamical vector properties of the title reaction in the ground electronic state X2A’ potential energy surface （PES）[Zanchet et al. 2006 J. Phys. Chem. A 110 12017] are theoretically predicted using the quasi-classical trajectory （QCT） method for the first time. The calculated results reveal that the smallest value of the rotational quantum number j, larger vibrational quantum number v, and the lower strength of collision energy should be selected for offering the most obvious picture about the stereodynamical vector properties. Polarization-dependent differential cross sections and the angular momentum alignment distribution, P（θr） and P（Φr） in the center-of-mass frame, are obtained to gain an insight into the alignment and orientation of the product molecules. The rotational angular momentum vector j’ of CO is aligned to be perpendicular to reagent relative velocity k. The product polarizations align along the y axis, pointing to the positive direction of the y axis. A new method is developed to investigate massive reactions with various initial states and to further study the vector properties of the fundamental reactions in detail.     

Study of the 24Mg(α, 12C)16O reaction in the energy range Elab = 24.9–27.76 MeV

The ²⁴Mg(α,¹²C)¹⁶O and ²⁴Mg(α, α')²⁴Mg reactions have been used to search for resonances in the ²⁸Si compound nucleus. The excitation functions were measured in the energy range between 24.9 and 27.76 MeV. Angular distributions of ¹²C nuclei and elastic and inelastic scattering of α-particles have been measured at energies corresponding to extrema of excitation functions. Significant anomalies have been found at E_ex = 31.5 and 33,1 MeV. The spins and parities of these structures are assigned as 9⁻ and 11⁻, respectively.     

Determination of Astrophysical 13N（p,γ）^14O S-factors from the Asymptotic Normalization Coefficient of ^14C→^13C ＋ n

The angular distribution of the ^13C（d,p）^14C reaction is reanalysed using the Johnson-Soper approach. The squared asymptotic normalization coefficient （ANC） of virtual decay ^14 C →^13 C^14＋ n is then derived to be 21.4±5.0 fm^-1. The squared ANC and spectroscopic factor （SF） of ^14O→^13N ＋p are extracted to be 30.4± 7.1 fm^-1 and 1.94 ± 0.45, respectively. The astrophysical S-factors and reaction rates of ^13N（p, γ）140 are determined from the ANC of ^14O → ^13N ＋ P using the R-matrix approach.     

Determination of the stellar reaction rate for 12C（α,γ）16O： using a new expression with the reaction mechanism

The astrophysical reaction rate of 12C(α, γ)16O plays a key role in massive star evolution. However, this reaction rate and its uncertainties have not been well determined yet, especially at T9=0.2. The existing results even disagree with each other to a certain extent. In this paper, the E1, E2 and total (E1+E2) 12C(α, γ)16O reaction rates are calculated in the temperature range from T9=0.3 to 2 according to all the available cross section data. A new analytic expression of the 12 C(α, γ)16 O reaction rate is brought forward based on the reaction mechanism. In this expression, each part embodies the underlying physics of the reaction. Unlike previous works, some physical parameters are chosen from experimental results directly, instead of all the parameters obtained from fitting. These parameters in the new expression, with their 3σ fit errors, are obtained from fit to our calculated reaction rate from T9=0.3 to 2. Using the fit results, the analytic expression of 12C(α, γ)16O reaction rate is extrapolated down to T9=0.05 based on the underlying physics. The 12C(α, γ)16 O reaction rate at T9=0.2 is (8.78 ± 1.52) × 1015 cm3s-1mol-1. Some comparisons and discussions about our new 12 C(α, γ)16 O reaction rate are presented, and the contributions of the reaction rate correspond to the different part of reaction mechanism are given. The agreements of the reaction rate below T9=2 between our results and previous works indicate that our results are reliable, and they could be included in the astrophysical reaction rate network. Furthermore, we believe our method to investigate the 12C(α, γ)16O reaction rate is reasonable, and this method can also be employed to study the reaction rate of other astrophysical reactions. Finally, a new constraint of the supernovae production factor of some isotopes are illustrated according to our 12C(α, γ)16O reaction rates.     

Astrophysical S-factor of the ~(12)C(α, γ)~(16)O reaction at solar energies

The astrophysical S-factor of the4He+12C radiative capture is calculated in the potential model at the energy range 0.1-2.0 MeV.Radiative capture12C(α,γ)16O is extremely relevant for the fate of massive stars and determines if the remnant of a supernova explosion becomes a black hole or a neutron star.Because this reaction occurs at low energies,the experimental measurements are very difficult and perhaps impossible.In this paper,radiative capture of the12C(α,γ)16O reaction at very low energies is taken as a case study.In comparison with other theoretical methods and available experimental data,good agreement is achieved for the astrophysical S-factor of this process.     

Line Intensities of (12)C(16)O(2) in the 1.2-1.4 µm Spectral Region

The 7000-8500 cm(-1) spectral region of (12)C(16)O(2) has been investigated using the high-resolution FT spectrometer of LPPM in Orsay. The two strongest bands in this region are the 10031 <-- 00001 and 10032 <-- 00001 bands centered at 8294 and 8192 cm(-1). Line intensities in these two bands and in the 40013 <-- 00001 and 40014 <-- 00001 bands have been measured. Using the method of effective operators, these line intensities have been included in a new fit of effective dipole-moment parameters to all available experimental data in the same spectral region of (12)C(16)O(2). The corresponding calculated line intensities of the 10031 <-- 00001 and 10032 <-- 00001 bands are compared with the experimental ones. Copyright 2000 Academic Press.     

The β-delayed α-spectrum of 16N,and its role in defining the astrophysical cross section for 12C(α,γ)16O

It has proven to be very difficult to determine the astrophysically important cross section for ¹²C(α, γ)¹⁶O at the relevant energies (∼300 keV) from radiative capture measurements. The present paper summarizes a new measurement of the β-delayed α-spectrum of ¹⁶N that substantially improves our knowledge of the E1 α-capture cross section on ¹²C at 300 keV. The paper concludes with a brief discussion of the status of the total ¹²C(α, γ)¹⁶O cross section at 300 keV.