Isomeric Level Research Articles

Reinvestigation of the excited states in the proton emitter Lu151 : Particle-hole excitations across the N=Z=64 subshell

The excited states of the proton emitter Lu151 were reinvestigated in a recoil-decay tagging experiment at the Accelerator Laboratory of the University of Jyväskylä (JYFL). The level scheme built on the ground state of Lu151 was updated with five new γ-ray transitions. Large-scale shell model calculations were carried out in the model space consisting of the neutron and proton orbitals 0g7/2, 1d5/2, 1d3/2, 2s1/2, and 0h11/2 with the optimized monopole interaction in order to interpret the experimental level scheme of Lu151. It is found that the excitation energies of states above the 27/2− and 23/2+ isomeric levels in Lu151 can be sensitive to excitations from g7/2 and d5/2 to single-particle orbitals above N=Z=64.Received 11 October 2017DOI:https://doi.org/10.1103/PhysRevC.96.064307©2017 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasElectromagnetic transitionsEnergy levels & level densitiesLow & intermediate energy heavy-ion reactionsNuclear spin & parityNuclear structure & decaysProton emissionShell modelProperties150 ≤ A ≤ 189Nuclear Physics

Isomeric Level of the 229Th Nucleus and Its Population in the Coulomb Excitation Reaction

Electromagnetical properties of the deformed neutron-odd nucleus of 229Th are considered on the basis of a unified nuclear model. Particular attention is given to the properties of the low-lying isomeric 3/2+ state. The possibility of its population in the Coulomb excitation reaction is studied.

Erratum: Radiative lifetime and energy of the low-energy isomeric level in 229Th [Phys. Rev. C 92 , 054324 (2015)

Erratum: Radiative lifetime and energy of the low-energy isomeric level in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msup><mml:mrow /><mml:mn>229</mml:mn></mml:msup><mml:mi>Th</mml:mi></mml:mrow></mml:math> [Phys. Rev. C <b>92</b> , 054324 (2015)

Mass Spectrometric Discrimination of Squalene Monohydroperoxide Isomers.

Squalene (SQ), a main component of human sebum, is readily photooxidized by exposure to sunlight, producing six squalene monohydroperoxide (SQ-OOH) isomers. Despite its known connection to various skin conditions, few studies have sought to analyze SQ-OOH at the isomeric level. In this study, we aimed to develop a method to discriminate each SQ-OOH isomer with the use of tandem mass spectrometry (MS/MS). The six standard SQ-OOH isomers were prepared by photooxidizing SQ in the presence of rose bengal, a photosensitizer, and isolated by semipreparative high-performance liquid chromatography (HPLC). To purify each isomer, 2-methoxypropene, which reversibly reacts with the hydroperoxide group of SQ-OOH, was utilized. Product ion scanning was then performed on the standard SQ-OOH isomers in the absence and presence of the sodium ion. In the absence of the sodium ion, the fragmentation patterns produced by atmospheric pressure chemical ionization were similar between the isomers, whereas in the presence of the sodium ion by electrospray ionization, unique fragmentation patterns were achieved. Based on these fragment ions, HPLC-MS/MS multiple reaction monitoring analysis was conducted on a mixture of the standard SQ-OOH isomers. We achieved discrimination of SQ-OOH isomers with high selectivity and detected SQ-OOH isomers at nanogram levels. These results may improve our understanding of the effect of SQ-OOH on skin conditions as well as the mechanism behind SQ peroxidation.

Catalytic conversion of stearic acid to fuel oil in a hydrogen donor

Stearic acid (SA) was dispersed in tetralin (a hydrogen donor) and hydrotreated in a batch reactor over a fabricated sulfided NiMo/γ-Al2O3-β-zeolite catalyst to obtain a diesel-range fuel product. NiMo/γ-Al2O3-β-zeolite catalysts were prepared by loading the active components NiO and MoO3 onto a mechanically mixed γ-Al2O3 and β-zeolite support, followed by a sulfurization procedure. The effects of the catalytic properties and reaction conditions on the hydrodeoxygenation of SA were investigated. The results showed that increasing the β-zeolite in the support leads to a decrease in SA conversion and an increase in the isomerization of products; increasing the NiO and MoO3 mass fraction tends to promote the formation of alkene hydrocarbons and increase the level of isomerization; increasing the Ni molar fraction helps to promote both conversion and isomerization; and temperatures above 330 °C promoted the activities of the catalysts and tetralin. A nearly 90% SA conversion was achieved at 350 °C under H2 at a pressure of 0.8 MPa for 2 h in tetralin. The total content of C16C18 alkanes and alkenes in the products was about 98%, and the isomerized compounds accounted for 10–40 wt%.

Short-lived isomers inPo192andPo194

Isomeric states in $^{194}\mathrm{Po}$ and $^{192}\mathrm{Po}$ were studied at the velocity filter SHIP. The isotopes were produced in the fusion-evaporation reactions $^{141}\mathrm{Pr}$($^{56}\mathrm{Fe}, \mathrm{p}2\mathrm{n})^{194}\mathrm{Po}$ and $^{144}\mathrm{Sm}$($^{51}\mathrm{V}, \mathrm{p}2\mathrm{n})^{192}\mathrm{Po}$. Several new $\ensuremath{\gamma}$-ray transitions were attributed to the isomers and $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ coincidences for both isomers were studied for the first time. The 459-keV transition earlier, tentatively proposed as de-exciting the isomeric level in $^{194}\mathrm{Po}$, was replaced by a new 248-keV transition, and the spin of this isomer was reassigned from (${11}^{\ensuremath{-}}$) to (${10}^{\ensuremath{-}}$). The de-excitation of the (${11}^{\ensuremath{-}}$) isomeric level in $^{192}\mathrm{Po}$ by the 154-keV transition was confirmed and a parallel de-excitation by a 733-keV ($E3$) transition to (${8}^{+}$) level of the ground-state band was suggested. Moreover, side feeding to the (${4}^{+}$) level of the ground-state band was proposed. The paper also discusses strengths of transitions de-exciting ${11}^{\ensuremath{-}}$ isomers in neighboring Po and Pb isotopes.

Nuclear Properties of vg9/2+ Isomers in Odd 59Cr to 69Se Nuclei for N=35

&lt;p class="1Body"&gt;We have reported the systematic magnetic quadrupole reduced transition probabilities B (M2) between 9/2&lt;sup&gt;+&lt;/sup&gt; and 5/2&lt;sup&gt;-&lt;/sup&gt; in odd &lt;sup&gt;59&lt;/sup&gt;Cr to &lt;sup&gt;69&lt;/sup&gt;Se nuclei for neutron N=35. At present work the calculated B(M2) values are 0.079 W.U., 0.067 W.U., 0.230 W.U., 0.412 W.U., 0.060 W.U., and 0.044 W.U. for &lt;sup&gt;59&lt;/sup&gt;Cr, &lt;sup&gt;61&lt;/sup&gt;Fe, &lt;sup&gt;63&lt;/sup&gt;Ni, &lt;sup&gt;65&lt;/sup&gt;Zn, &lt;sup&gt;67&lt;/sup&gt;Ge, and &lt;sup&gt;69&lt;/sup&gt;Se nuclei respectively. The theoretical calculations of the reduced transition probabilities were compared to the previous experimental values. The width of isomeric levels, mean-life and Weisskopf hindrance factors in the odd &lt;sup&gt;59&lt;/sup&gt;Cr to &lt;sup&gt;69&lt;/sup&gt;Se nuclei were also calculated. The isomeric levels 9/2&lt;sup&gt;+&lt;/sup&gt; were systematically studied as a function of even atomic number from 24 to 34. It is shown that the isomeric levels are increases from Z= 24 to Z= 28 and then decreases monotonically up to Z= 34.&lt;/p&gt;

Associations between isomeric serum methdone levels, total sugar intake, and orexin-A

Associations between isomeric serum methdone levels, total sugar intake, and orexin-A

Nuclear Data Sheets for A = 87

The evaluated experimental data are presented for 14 known nuclides of mass 87 (Ga, Ge, As, Se, Br, Kr, Rb, Sr, Y, Zr, Nb, Mo, Tc, Ru). New datasets have been added for 87Ga, 87Se, 87Kr, 87Rb, 87Sr, 87Nb, and 87Tc. The observation of and new lifetime measurements for 87As at the NSCL Coupled Cyclotron Facility and the Oak Ridge Isochronous Cyclotron at the HRIBF–ORNL Facility are included in the adopted levels for this isotope. The new evaluation also includes an isomeric level at unknown energy for 87Tc, changes to the adopted levels for 87Nb based on newly published data including an extension of the high spin levels and new lifetime measurements, and new heavy ion data for 87Kr. New high spin levels for 87Rb were observed, indicating possible neutron core excitations. In addition, the ground state lifetime of 87Rb has been revised and a new lifetime measurement for an excited level in 87Rb indicates a possible proton spin flip. New excitation levels have been observed for the first time in 87Se. New direct and precise measurement of atomic masses of 87Tc, 87Mo, 87Nb, 87Zr, 87Mo and 87Tc have greatly improved the Q value landscape in this mass region. This work supersedes the previous A=87 evaluation published in 2002He09, and Q values for all isotopes were updated to incorporate the mass evaluation in 2012Wa38.

Progress in the structural studies of proton emitters

Studies of nuclei far from the β stability line have been at the forefront of nuclear structure research. Proton radioactivity is an important decay mode for nuclei near the proton drip-line. Studies of this decay mode can reveal valuable information on exotic nuclear structure and provide deep insights on the organization of nuclei in extreme conditions. For example, recent advances in modern experimental techniques have allowed the measurement of the detailed rotational structure of proton emitters. Yu et al. of the Oak Ridge National Laboratory identified states in the ground-state proton emitter 151Lu, which were populated by using the recoil-decay tagging technique. The systematic data suggested a possible isomeric level at high spin in 151Lu. In addition, by using the same technique, Seweryniak et al. of the Argonne National Laboratory observed rotational bands feeding the ground state and the isomeric state in the proton emitter 141Ho. These authors showed that, by using a state-of-the-art detection system, it is possible to study excited states in nuclei produced with sub 100 nb cross-sections. These new experimental data have given us valuable information for understanding the interactions in exotic systems, which motivate further theoretical development. For example, in the experimental work of Seweryniak et al., the authors challenged existing theoretical models to include non-axial degrees of freedom in the nuclear potential in calculations of proton decay rates. In this article, we provide a brief review on the recent progress in the studies of proton emitters, with an emphasis on introducing exciting theoretical models. A good model should not only yield the decay rates, but should also contain microscopic degrees of freedom that provide information on the detailed structure. This requires developing theoretical models that extend beyond the semi-classical methods, for example those based on the particle-rotor model. We mention several such attempts that are documented in the literature, including the relativistic Hartree-Bogoliubov model of Vretenar, Lalazissis, and Ring, and the most recent application of the projected shell model by the current authors.

Isomeric and ground state energy level measurements of natural tellurium isotopes via (γ,n) reaction

We have planned to measure isomeric and ground state energy levels in 120Te(γ,n)119m,gTe, 122Te(γ,n)121m,gTe, 128Te(γ,n)127m,gTe, 130Te(γ,n)129m,gTe photonuclear reactions of natural tellurium induced by bremsstrahlung photons with end-point energy at 18 MeV. The sample was irradiated in the clinical linear electron accelerator (Philips SLi-25) at Akdeniz University Hospital. The gamma spectrum of the tellurium sample was measured using HP(Ge) semiconductor detector (ORTEC) and multi channel analyzer. We used both MAESTRO (ORTEC) and home made root based gui program (Theia) for data analyzing. The obtained experimental data values are compared with NUDAT energy values.

Profiling of the molecular weight and structural isomer abundance of macroalgae-derived phlorotannins.

Phlorotannins are a group of complex polymers of phloroglucinol (1,3,5-trihydroxybenzene) unique to macroalgae. These phenolic compounds are integral structural components of the cell wall in brown algae, but also play many secondary ecological roles such as protection from UV radiation and defense against grazing. This study employed Ultra Performance Liquid Chromatography (UPLC) with tandem mass spectrometry to investigate isomeric complexity and observed differences in phlorotannins derived from macroalgae harvested off the Irish coast (Fucus serratus, Fucus vesiculosus, Himanthalia elongata and Cystoseira nodicaulis). Antioxidant activity and total phenolic content assays were used as an index for producing phlorotannin fractions, enriched using molecular weight cut-off dialysis with subsequent flash chromatography to profile phlorotannin isomers in these macroalgae. These fractions were profiled using UPLC-MS with multiple reaction monitoring (MRM) and the level of isomerization for specific molecular weight phlorotannins between 3 and 16 monomers were determined. The majority of the low molecular weight (LMW) phlorotannins were found to have a molecular weight range equivalent to 4–12 monomers of phloroglucinol. The level of isomerization within the individual macroalgal species differed, resulting in substantially different numbers of phlorotannin isomers for particular molecular weights. F. vesiculosus had the highest number of isomers of 61 at one specific molecular mass, corresponding to 12 phloroglucinol units (PGUs). These results highlight the complex nature of these extracts and emphasize the challenges involved in structural elucidation of these compounds.

Low-lying isomeric states in Ga80 from the β− decay of Zn80

A new level scheme of 80Ga has been determined. This nucleus was populated following the β− decay of 80Zn at ISOLDE, CERN. The proposed level scheme is significantly different compared to the previously reported one and contains 26 levels up to 3.4 MeV in excitation energy. The present study establishes that the previously identified 1.9-s β− -decaying 6− isomer is the ground state of 80Ga and the 1.3-s β− -decaying 3− isomer lies at an excitation energy of 22.4 keV. A new isomeric level was identified at 707.8 keV and its half-life was measured to be 18.3(5) ns, allowing the 685.4-keV transition de-exciting this state to be assigned anM2 multipolarity. The newly measured spectroscopic observables are compared with shell-model calculations using the jj44bpn and JUN45 interactions.

Transformation of ethylbenzene-m-xylene feed over MCM-22 zeolites with different acidities

Transformation of ethylbenzene (EB, 22wt%)-m-xylene (78wt%) mixture was carried out over zeolite MCM-22 catalysts with different acidities. The modification of the number and strength of the acid sites was attained by: (i) dealumination by steaming and successive acid treatment and (ii) isomorphous substitution of framework Al for boron ([Al,B]MCM-22). The effect of platinum introduction was also investigated. The strong decrease in the Brønsted acidity, concomitant to the dealumination procedure, appears unfavorable since it leads to a drastic diminish of the degree of EB conversion, not compensated by satisfactory level of m-xylene isomerization. [Al,B]MCM-22 is a modification with much better performance, most probably because it contains both strong, Al-connected acid sites but in lower amount than in the parent sample, and weaker boron-generated sites and practically no any Lewis sites.Parent zeolite [Al]MCM-22 as well as B-substitution possess promising properties for ethylbenzene-m-xylene mixture transformation catalyst with adequate degree of EB conversion and extent of p-xylene approach to equilibrium as well as low xylene loss.

Isomerization During Olefin Metathesis: An Assessment of Potential Catalyst Culprits

AbstractTwo ruthenium hydride complexes commonly proposed as agents of unintended isomerization during olefin metathesis are examined for their activity in isomerization of estragole, a representative allylbenzene. Neither proves kinetically competent to account for the levels of isomerization observed during cross‐metathesis of estragole by the second‐generation Grubbs catalyst. A structure–activity analysis of selected ruthenium hydride complexes indicates that higher isomerization activity correlates with a more electrophilic metal center.

Effects of Boron-Containing Lewis Acids on Olefin Metathesis

Boron-containing Lewis acids have shown a profound effect on the cross-metathesis reaction of 1-hexene. Grubbs first-generation catalyst shows over 100% improvement in conversion in some cases, while the yields increase by up to 50% with Grubbs second-generation catalyst. With the inclusion of boron-containing Lewis acids, compounds prepared using Grubbs second-generation-type catalysts display significantly reduced levels of isomerization.

Rotational bands in113Sb

Rotational bands in ${}^{113}$Sb, populated in the reaction ${}^{100}$Mo(${}^{19}$F,$6n$) at a beam energy of 105 MeV, have been studied. Two previously reported strongly coupled high-$K$ bands have been extended and a new sequence of five states, linked to the positive-parity high-$K$ band through interband transitions, is proposed. A comparison of the experimental $B(M1)/B(E2)$ ratios for the latter band with the predictions of the geometrical model of D$\stackrel{\ifmmode \ddot{}\else \&#34;{}\fi{}}{\mathrm{o}}$nau-Frauendorf suggests that the states are axially symmetric with a moderate quadrupole deformation of ${\ensuremath{\beta}}_{2}=0.20$. Present directional correlation orientation and $\ensuremath{\gamma}$-ray polarization studies indicate that the negative-parity states built upon the 3045 keV isomeric level involve a high-$\ensuremath{\Omega}$ $\ensuremath{\pi}{h}_{11/2}$ orbital and have an oblate shape. Mean lifetimes for eight states belonging to the prolate-deformed $\ensuremath{\pi}{h}_{11/2}$ band have been measured from Doppler shift attenuation data. The results suggest a large average quadrupole deformation of ${\ensuremath{\beta}}_{2}=0.32\ifmmode\pm\else\textpm\fi{}0.03$ for states up to 10217 keV. The decrease of the $B$($E$2) rates for the 9063- and 10217 keV states may be interpreted as a signature of band termination at high spin.

Low energy isomeric levels of nuclei near N=40

We present the results of an experiment in which the structure of neutron-rich nuclei located in the vicinity of N=40 was studied. The importance of our results comes from the fact that knowing the behaviour of the neutron g9/2 orbital with increasing number of neutrons is one of the key points in defining the structure of these nuclei at low excitation energy. The nuclei of interest were produced by fragmentation of a 86Kr beam at 60MeV/u on a thick Be target at GANIL (France). Preliminary results on 75Cu and 78Ga isomers will be presented together with tentative spin and parity assignments.

From Molecular Hollows to Imprinting Strategies – Mass-Sensitive Devices in Host-Guest Chemistry

Chemically sensitive coatings via supra-molecular chemistry are preferably combined with mass-sensitive devices. Thus, the quartz-crystal-balance (QCM) and the surface acoustic wave (SAW) oscillator allow monitoring inclusion phenomena from nano- gram down to the sub-femto-gram range. A deeper insight into the inclusion process of analytes by e.g. cyclodextrines, calixarenes and paracyclophanes is obtained by modelling procedures, which offer to predict the sensitivity and selectivity of sensor coatings. The robustness of the materials is further enhanced by cross-linking which leads to functionalized polymers. This strategy is further developed by templating, in most cases identical to analytes, the polymer materials enable us to perform both gas- and liquid-phase measurements due to their inertness. The flexibility of imprinting technique allows us to produce more selective and optimized recognition sites for the detection of aromatic, halogenated, polycyclic hydrocarbons and even complex mixtures e.g. oil degradation, composting are also accessible to monitor at isomeric level.

Isomeric levels in92Rb and the structure of neutron-rich92,94Rb isotopes

The medium-spin structure of the ${}^{92}$Rb nucleus, populated in spontaneous fission of ${}^{248}$Cm and ${}^{252}$Cf, has been studied using the EUROGAM2 and the GAMMASPHERE Ge arrays, respectively. Two isomers have been found in ${}^{92}$Rb at 284.2 and 1958.2 keV with half-lives of ${T}_{1/2}=54(3)$ ns and ${T}_{1/2}=7(2)$ ns, respectively. A measurement of neutron-induced fission of ${}^{235}$U, at the PF1B cold-neutron beam facility of the Institut Laue Langevin, Grenoble, has been performed to confirm the assignment of the ${T}_{1/2}=54(3)$ ns, 284.2-keV isomeric level to the ${}^{92}$Rb nucleus. Excited levels in ${}^{92}$Rb and ${}^{94}$Rb nuclei have been calculated in a large-scale shell-model framework. Isomers observed in these two nuclei have been interpreted as proton-neutron configurations involving the high-$j$ $\ensuremath{\nu}1{h}_{11/2}$ and $\ensuremath{\pi}1{g}_{9/2}$ orbitals.