Partial Cross Research Articles

Experimental Determination of Third Derivative of the Gibbs Free Energy, G II: Differential Pressure Perturbation Calorimetry

We have been evaluating third derivative quantities of the Gibbs free energy, G, by graphically differentiating the second derivatives that are accessible experimentally, and demonstrated their power in elucidating the mixing schemes in aqueous solutions. Here we determine directly one of the third derivatives of G, the partial molar entropy-volume cross fluctuation density of 2-butoxyethanol (BE) in the BE–H2O system, SV δ BE . The difference of the heats of compression were directly determined using two identical cells and applying the same pressure change to both cells concurrently. Both cells are filled with sample solutions having a small appropriate difference in mole fraction. The results indicated that this method is feasible with the prior knowledge of the thermal expansivity of the solution to within a few per cent accuracy. If the volumes of the two cells are identical within the order of 0.01%, the method provides the required results to within 0.1% without the thermal expansivity data. This success opens a possibility of evaluating the fourth derivative graphically, which is expected to provide much more detailed information about the molecular processes in aqueous solutions.

NEW GENOTYPES OF HIBISCUS × ROSA-SINENSIS THROUGH CLASSICAL BREEDING AND GENETIC TRANSFORMATION

Since 2006, a breeding programme for Hibiscus rosa-sinensis was established at CRA-FSO, Italy. The aim is to select specific cultivars suitable for pot plant production and well-adapted to the Mediterranean climate. A partial diallelic cross design (reciprocals without self-fecundations) was used to test crossing ability of the collected cultivars. However, only a limited number of cross combinations resulted in progenies with desirable characters. The first selected cultivars are presented. At the same time, we followed another approach to investigate whether desirable morphological modifications (plant size reduction for pot plant cultivation) could be obtained by transforming H. x rosa-sinensis with Agrobacterium rhizogenes. In vitro seedlings were used as sources of explants for the transformation experiments. Two A. rhizogenes strains (ATCC 15834 and NCPPB 1855) were used. Axenic hairy root cultures were established about 4 months after inoculation. Hairy roots grew vigorously on hormone free medium whereas normal roots did not. Transformed roots displayed a typical hairy root phenotype characterized by fast growth, high lateral branching and lack of geotropism. So far, after more than one year of cultivation, a clone of hairy root deriving from a cotyledon formed a friable yellowish callus at root node level and several adventitious buds are spontaneously regenerating from it.

Theoretical calculation of the low-energy scattering cross sections for He-Li2 system

In this paper, the Fuchs potential model and the Close-coupling method are used to calculate the low-energy cross sections for a He-Li2 scattering system. The dependences of total cross section on energies, differential section on angles, and partial wave cross section on quantum number of total angular momentum are discussed . The quantum effect on energy obtained.

Investigation of the role of the projectile-target orientation angles on the evaporation residue production

The measured yield of evaporation residues in reactions with massive nuclei have been well reproduced by using the partial fusion and quasifission cross sections obtained in the dinuclear-system model. The influence of the orientation angles of the projectile- and target-nucleus symmetry axes relative to the beam direction on the production of the evaporation residues is investigated for the 48Ca + 154Sm reaction as a function of the beam energy. At the low beam energies only the orientation angles close to αP = 30° (projectile) and αP = 0°–15° (target) can contribute to the formation of evaporation residues. At large beam energies (about Ec.m. = 140–180 MeV) the collisions at all values of orientation angles αP and αT of reactants can contribute to the evaporation residue cross section which ranges between 10–100 mb, while at Ec.m. > 185 MeV the evaporation residue cross section ranges between 0.1–1 mb because the fission barrier for the compound nucleus decreases by increasing its excitation energy and angular momentum.

Nonblocking Four-Stage Multicast Network for Multicast-Capable Optical Cross Connects

In this paper, we investigate the four-stage multicast network with only two multicast stages (the second and output stages) being multicast-capable, which is called 4(2 m)-stage multicast network. We first derive the sufficient wide-sense nonblocking (WSNB) and rearrangeable nonblocking (RNB) conditions for the 4(2 m)-stage multicast network. The WSNB and RNB conditions are also presented for multicast request with limited multicast degree. The 4(2 m)-stage multicast network needs at least O(N 3 / 2) crosspoints to be WSNB and RNB, which is a lower bound than the three-stage Clos network with two multicast stages and the same bound with the four-stage network with three multicast stages. Then we design full and partial multicast-capable optical cross connects (MC-OXCs) applying the 4(2 m)-stage multicast network. The proposed WSNB full MC-OXC with two multicast stages is power efficient in reducing splitting loss and has lower multicast cost, compared with the one having three multicast stages. Partial MC-OXC with only one multicast stage is proposed to further reduce the multicast cost and splitting loss. The RNB MC-OXCs with one or two multicast stages provide better performance at the respects of crosspoints, multicast cost, and splitting loss than their WSNB counterparts.

Coupled-channel investigation of rotationally and vibrationally inelastic collisions between He and H2

The coupled-channel formalism has been employed for He + H2 collisions including rotational (j = 0, 2) and vibrational (n = 0, 1) levels and making use of the Kraus-Mies potential energy surface. Integral and differential cross sections are obtained at the total energies 0.3884, 0.9, and 1.4116 eV for rotational and vibrational transitions separately, and for the combined processes. Considerable use has been made of the microscopic reversibility principle to extract cross sections from the S matrix for de-excitations as well as for excitations. Cross sections for vibrational excitation are found to decrease when accompanied by rotational excitation. For vibrational de-excitation, the effect of rotational excitation is to increase the cross sections. Defining a most probable impact parameter bmax from the maximum in the partial integral cross sections, vibration excitation is found to occur at low bmax, while rotational excitation is observed at comparatively higher values. For simultaneous rotational and transitions, bmax decreases with increasing energy transfer. A deflection angle ©(cl is defined in terms of the impact parameters and the turning point radii for the initial and final channels, and a correlation between this angle and the maxima in the computed angular distributions is found. The transition probabilities for the rotational excitation j = 0 2 with simultaneous vibrational excitation and their physical interpretation are also discussed within the total angular momentum coupling scheme.

POSSIBLE POSITRONIUM FORMATION IN THE COLLISIONS OF POSITRONS WITH CALCIUM AND STRONTIUM POSITIVE IONS

The inelastic collisions of positrons with calcium and strontium positive ions are treated for the first time as a three-channel problem within the framework of the improved coupled-static and frozen-core approximations with the assumption that the elastic, ground positronium and excited-positronium formation channels are open. The calculations of the partial and total cross sections are carried out for eight values of the total angular momentum ℓ (0 ≤ ℓ ≤7), at 20 values of the incident energy lying above the excited positronium formation threshold and extending to a wide region above the ionization threshold of the target ion. The total collisional positronium formation cross sections of e+– Sr+scattering show a peak around the ionization threshold of Sr+but display a peak at 30 eV for e+– Ca+scattering. In both scattering problems the total excited Ps formation cross sections have considerable values in the energy range [Formula: see text].

COMPARISON OF THE FUSION-FISSION AND QUASIFISSION MECHANISMS IN HEAVY-ION COLLISIONS

The decrease of the evaporation residue yields in reactions with massive nuclei is explained by an increase of the competition between quasifission and complete fusion processes and by the decrease of the survival probability of the heated and rotating nuclei against fission along the de-excitation cascade of the compound nucleus. The experimental data on the yields of evaporation residue, fusion-fission and quasifission fragments in the 48 Ca + 154 Sm reaction are analyzed in the framework of the combined theoretical method based on the dinuclear system concept and advanced statistical model. The measured yields of evaporation residues of the 48 Ca + 154 Sm reaction have been well reproduced and yields of fission fragments were analyzed using the partial fusion and quasifission cross sections calculated in the dinuclear system model. Such a way of calculation is used to find optimal conditions for the synthesis of the new element Z = 120 (A = 302) by studying the excitation functions of evaporation residues of the 54 Cr + 248 Cm , 58 Fe + 244 Pu , and 64 Ni + 238 U reactions. Our estimations show that the 54 Cr + 248 Cm reaction is preferable in comparison with the two others.

Elastic collisions between O and D atoms at low temperature and accurate analytic potential energy function and molecular constants of the OD（X2Π） radical

Interaction potential of the OD（X2Π） radical is constructed by employing the CCSD（T） theory in combination with the correlationconsistent quintuple basis set, augccpV5Z, in the valence range. Using the potential, the spectroscopic parameters are accurately determined. The present D0, De, Re, ωe, ωeχe and Be values are of 44574, 46225 eV, 009702 nm, 2724923, 453534 and 100096 cm-1, respectively, which are in excellent agreement with the recent measurements wherever available. A total of 23 vibrational states have been found when J = 0 by solving the radial Schrdinger equation of nuclear motion. The complete vibrational levels, classical turning points, initial rotation and centrifugal distortion constants when J = 0 are reported for the first time, which are in good agreement with the available experimental results. The total and various partialwave cross sections are calculated for the elastic collisions of O and D atoms in their ground states at low and ultralow temperatures when the two atoms approach each other along the OD（X2Π） potential energy curve. The impact energy range covers a vange from 10×10-11 to 10 ×10-3a.u.. One shape resonance has been found in the total elastic cross sections. Contribution to the total elastic cross sections by each partial wave is investigated carefully. The results show that the shape of the total elastic cross sections is mainly dominated by the s partial wave. The shape resonances coming from the higher partial waves are covered up by the strong s partial wave cross sections.

Genetic divergence in popcorn lines detected by microsatellite markers

The purpose of this study was to use microsatellite markers to evaluate the genetic divergence in 10 popcorn lines. The number of alleles per locus ranged from 2 to 5. The proportion of polymorphic loci was highest (50%) in line Curagua, while Zelia II was the most monomorphic (100%). The arithmetic complement of similarity of Roger and Tanimoto for the 10 lines indicated lower genetic similarity between the lines Zelia II and Avati Pichinga I and higher similarity between Zelia I and Zelia II. The mean distance between groups was greatest between the group formed by lines IAC 112 I 112 IAC II, Avati Pichinga I, Avati Pichinga II and the group containing Yellow Pear Popcorn II. Strategies on how to use the heterosis between different lines in partial diallel crosses are indicated.

Recent developments of prompt gamma activation analysis at Budapest

The PGAA facility at the Budapest Research Reactor has been continually upgraded and developed since its start-up in 1996, as a result of which its performance has improved considerably. The installation of the cold neutron source, the partial change to supermirror neutron guides and their realignment increased the flux by almost two orders of magnitude. The data acquisition has been modernized as well; digital spectrometers were tested and implemented in novel forms of gamma-ray spectrum collection. This year a higher-efficiency HPGe detector and a new data acquisition module were put into operation. Most recently all the neutron guides were changed to supermirror-coated ones to further increase the neutron flux. The improved evaluation software makes possible a more reliable elemental analysis of the samples. In this progress report these developments are critically reviewed. The characteristics of the latest system are also described. It is the first time that a set of new partial gamma-ray production cross sections are presented, which are based on the new intensity values of 14N(n,γ)15N calibration standard.

Study of isotope effect in 3He(4He)-H2 collisions

Close-coupling equation is applied to the 3He(4He)-H2 system，and the rotational excitation cross sections for incidence energy of 05eV are calculated.By analyzing the differences between these partial wave cross sections and differential cross sections，the change of the partial wave cross sections and differential cross sections with increase of quantum number，as well as with the change of the mass of isotope atom are found out. Based on the calculation，the effect of isotopic substitution on atom-diatom collision is discussed.

Simulation of Gas-Phase Kinetics in $\hbox{CHF}_{3}:\hbox{H}_{2}: \hbox{O}_{2}$ Mixtures

A gas-phase reaction model for and mixtures was developed. Self-consistent electron impact cross-section set for was introduced. The original total and partial dissociation cross sections were received. A developed gas-phase kinetic scheme was tested on the experimental data. An important role of the chain reactions in the kinetics of F and H atoms and radicals was revealed.

Absolute partial photoionization cross sections of ozone

Despite the current concerns about ozone, absolute partial photoionization cross sections for this molecule in the vacuum ultraviolet (valence) region have been unavailable. By eclectic re-evaluation of old/new data and plausible assumptions, such cross sections have been assembled to fill this void.

Shape resonances in the absoluteK-shell photodetachment ofB−

$K$-shell photodetachment of ${\mathrm{B}}^{\ensuremath{-}}$ has been measured using the collinear photon-ion beamline at the Advanced Light Source, Lawrence Berkeley National Laboratory, as well as calculated using two separate $R$-matrix methods. The measurement of the absolute photodetachment cross section, as a function of photon energy, exhibits three near-threshold shape resonances due to the $^{3}S$, $^{3}P$, and $^{3}D$ final partial waves. A fit to the measured data using three resonance profiles shows good overall qualitative agreement with the three partial wave cross sections calculated using either $R$-matrix method. However, certain significant and unresolved quantitative discrepancies exist between the experimentally inferred and the calculated resonance profiles.

“Reading” the photoelectronβ-parameter spectrum in a resonance region

The behavior of the dipole photoelectron angular distribution parameter ${\ensuremath{\beta}}_{nl}(\ensuremath{\omega})$ in the vicinity of autoionizing resonances is discussed. It is shown that from this behavior, surprisingly, many photoionization parameters that cannot be measured experimentally can be extracted. These are the energy positions and ordering of autoionizing resonance minima in the partial photoionization cross sections ${\ensuremath{\sigma}}_{l+1}$ and ${\ensuremath{\sigma}}_{l\ensuremath{-}1}$, the energies at which these two cross sections intersect, and signs and magnitudes of the $\mathrm{cos}({\ensuremath{\delta}}_{l+1}\ensuremath{-}{\ensuremath{\delta}}_{l\ensuremath{-}1})$ (${\ensuremath{\delta}}_{l\ifmmode\pm\else\textpm\fi{}1}$ being the phase shifts of the dipole photoionization amplitudes ${D}_{l\ifmmode\pm\else\textpm\fi{}1}$, respectively) through the autoionizing resonance energy region. Based on this, a deeper interpretation of such effects as the width-narrowing, width-fluctuating, and $q$-reversal in the ${\ensuremath{\beta}}_{nl}$ parameter spectrum in the autoionizing resonance energy region is given. As an example, calculated data for partial photoionization cross sections ${\ensuremath{\sigma}}_{3d\ensuremath{\rightarrow}f}$ and ${\ensuremath{\sigma}}_{3d\ensuremath{\rightarrow}p}$, and ${\ensuremath{\beta}}_{3d}$ parameters for $3d$ photoelectrons from ${\mathrm{Cr}}^{+}$ are presented.

Physics impact of ILC Higgs coupling measurements: The effect of theory uncertainties

We study the effect of theoretical and parametric uncertainties on the ability of future Higgs coupling measurements at the International Linear Collider (ILC) to reveal deviations from the standard model (SM). To quantify the impact of these uncertainties we plot $\ensuremath{\Delta}{\ensuremath{\chi}}^{2}=25$ contours for the deviations between the SM Higgs couplings and the light Higgs couplings in the ${m}_{h}^{\mathrm{max}}$ benchmark scenario of the minimal supersymmetric standard model (MSSM). We consider the theoretical uncertainties in the SM Higgs decay partial widths and production cross section and the parametric uncertainties in the bottom and charm masses and the strong coupling ${\ensuremath{\alpha}}_{s}$. We find that the impact of the theoretical and parametric uncertainties is moderate in the first phase of ILC data-taking ($500\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ at 350 GeV center-of-mass energy), reducing the reach in the $CP$-odd MSSM Higgs mass ${M}_{A}$ by about 10% to $\ensuremath{\sim}500\text{ }\text{ }\mathrm{GeV}$, while in the second phase ($1000\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ at 1000 GeV) these uncertainties are larger than the experimental uncertainties and reduce the reach in ${M}_{A}$ by about a factor of 2, from $\ensuremath{\sim}1200$ down to $\ensuremath{\sim}600\text{ }\text{ }\mathrm{GeV}$. The bulk of the effect comes from the parametric uncertainties in ${m}_{b}$ and ${\ensuremath{\alpha}}_{s}$, followed by the theoretical uncertainty in ${\ensuremath{\Gamma}}_{b}$.

Study of cross sections for the loss of outer 1s, 2s, and 2p electrons by fast ions and atoms of light elements

In the case of light-element ions propagating with velocities V = 1.83 and 3.65 au in H2, He, N2, Ne, and Ar, the loss cross sections σi, i+m for m electrons (m = 1, 2, 3) are considered. The partial loss cross sections σi(nl) for one of the outer 1s, 2s, or 2p electrons are determined using the obtained data. It is shown that the experimental cross sections for the loss of the 1s and 2s electrons by positive ions qualitatively agree with the theoretical values calculated in the Born approximation. In the case of the ion velocity V = 1.83 au, the cross sections σi for 2p electrons are greater than the cross sections σi (1s) and σi (2s) by a factor of 1.2–3 for the same binding energies of electrons in the ion (I nl > 20 eV). It is found experimentally that, at V = 1.83 au, the cross sections σi (2p) for I nl ∼ 10–20 eV are less than the cross sections σi (1s) by a factor of 2–3, which is probably caused by a decrease in the screening parameter (θ2p < 1) of the outer shell of atoms.

Determination of outer molecular orbitals by collisional ionization experiments and comparison with Hartree-Fock, Kohn-Sham, and Dyson orbitals

Although the outer shapes of molecular orbitals (MO's) are of great importance in many phenomena, they have been difficult to be probed by experiments. Here we show that metastable helium (He{sup *}) atoms can sensitively probe the outer properties of molecules and that an electron spectroscopic technique using velocity-selected He{sup *} atoms in combination with classical trajectory simulations leads to a consistent determination of MO functions and the molecular surface. MO functions composed of linear combinations of atomic orbital functions were fitted to the observed collision energy dependences of partial ionization cross sections (CEDPICS). The obtained CEDPICS MO functions were compared with conventionally available Hartree-Fock, Kohn-Sham, and Dyson orbitals.

Comment on “Partial Photoionization Cross Sections and Angular Distributions for Double Excitation of Helium up to theN=13Threshold”

A Comment on the Letter by A. Czasch et al. [Phys. Rev. Lett. 95, 243003 (2005)]. The authors of the Letter offer a Reply.