Pd Nuclei Research Articles

Fabrication of a plasmonic sensor for surface-enhanced Raman spectroscopy using electroless deposition of Ag with hypophosphite

Surface-enhanced Raman spectroscopy (SERS) provides insights into electrode reaction processes due to its high selectivity towards the interface. It is necessary to ensure a stable and inexpensive supply of sensors to make this method more widely applicable. Techniques based on electrochemistry are efficient and suitable for mass manufacturing. In this research, two electroless processes for depositing Ag nanoparticles (NPs) on a glass substrate for sensor fabrication are discussed: one using ascorbic acid, the other hypophosphite. Specifically, the process using hypophosphite was achieved by forming Pd nuclei in the activating process. It turned out that when the ascorbic acid sensor is applied, undesired SERS signals originating from the reductant appear. By contrast, the hypophosphite sensor greatly reduces the unwanted signals. The optimized plasmonic sensor can achieve in situ SERS observation of electrochemical reactions without being restricted by electrode material and morphology.

Simultaneous description of β decay and low-lying structure of neutron-rich even- and odd-mass Rh and Pd nuclei

The low-energy structure and $\beta$ decay properties of neutron-rich even- and odd-mass Pd and Rh nuclei are studied using a mapping framework based on the nuclear density functional theory and the particle-boson coupling scheme. Constrained Hartree-Fock-Bogoliubov calculations using the Gogny-D1M energy density functional are performed to obtain microscopic inputs to determine the interacting-boson Hamiltonian employed to describe the even-even core Pd nuclei. The mean-field calculations also provide single-particle energies for the odd systems, which are used to determine essential ingredients of the particle-boson interactions for the odd-nucleon systems, and of the Gamow-Teller and Fermi transition operators. The potential energy surfaces obtained for even-even Pd isotopes as well as the spectroscopic properties for the even- and odd-mass systems suggest a transition from prolate deformed to $\gamma$-unstable and to nearly-spherical shapes. The predicted $\beta$ decay $\log{ft}$ values are shown to be sensitive to the details of the wave functions for the parent and daughter nuclei, and therefore serve as a stringent test of the employed theoretical approach.

Electroless Deposition of Pure Co on TaN Substrate for Interconnect Metallization

This work explores the electroless deposition of pure Co film on TaN substrate using Ti3+ as a reducing agent for interconnect metallization. Continuous and dense electroless-deposited (ELD) Co thin films with low surface roughness are obtained on the blanket and patterned structures using colloidal Sn/Pd activation. The effects of the Pd activation process on the Co nucleation, growth mechanisms, and the properties of the deposited Co films have been investigated in detail. The properties of the activated Pd nuclei decide the morphology and quality of the ELD Co films. The XPS results indicate that the ELD Co film is nearly pure Co film, with the metallic Co concentration of 99.2 at% and 99.4 at% for the as-deposited and annealed films, respectively. The resistivity of the Co film in 60 nm thick is as low as 13.6 μΩ·cm. Our results reveal that the ELD Co film is nanocrystalline with a mixture of the HCP and FCC structures. Further, the conformal ELD Co layer with good step coverage is deposited into the nanoscale trenches.

Possible multiple antimagnetic rotational bands in odd-A 103,105Pd and 109Cd nuclei * *Supported by the Science and Technology Research Planning Project of Jilin Provincial Department of Education (JJKH20220965KJ), and the National Natural Science Foundation of China (12175086, 11775098, U1867210, 11405072) and the Fundamental Research Funds for the Central Universities

The positive-parity signature partner bands in 103,105Pd and 109Cd nuclei are investigated using the classical particle-rotor model. Based on the systematic study of neighbouring nuclei, the signature partner bands of 105Pd are assigned to the configuration, and this assignment is also supported by the present calculations. Furthermore, the calculated values of such bands of 105Pd reproduce the experimental values well and exhibit a decrease with increasing angular momentum, suggesting that these two bands may originate from antimagnetic rotation. Similar signature partner bands are also found in the neighboring 103Pd and 109Cd nuclei. The properties of both bands are in general agreement with the fingerprints of antimagnetic rotation, and thus the signature partner bands of 103Pd and 109Cd are suggested to be candidates for the multiple antimagnetic rotational bands of 105Pd. In addition, the evolution of the two-shears-like mechanism for possible multiple antimagnetic rotational bands in 103,105Pd and 109Cd nuclei is examined by investigating the orientation of the angular momenta.

On the long-term stability of Pd-membranes with TiO2 intermediate layers for H2 purification

This work addresses the use of TiO 2 -based particles as an intermediate layer for reaching fully dense Pd-membranes by Electroless Pore-Plating for long-time hydrogen separation. Two different intermediate layers formed by raw and Pd-doped TiO 2 particles were considered. The estimated Pd-thickness of the composite membrane was reduced in half when the ceramic particles were doped with Pd nuclei before their incorporation onto the porous support by vacuum-assisted dip-coating. The real thickness of the top Pd-film was even lower (around 3 μm), as evidenced by the cross-section SEM images. However, a certain amount of palladium penetrates in some points of the porous structure of the support up to 50 μm in depth. In this manner, despite saving a noticeable amount of palladium during the membrane fabrication, lower H 2 -permeance was found while permeating pure hydrogen from the inner to the outer surface of the membrane at 400 °C (3.55·10 −4 against 4.59·10 −4 mol m −2 s −1 Pa −0.5 ). Certain concentration-polarization was found in the case of feeding binary H 2 –N 2 mixtures for all the conditions, especially in the case of reaching the porous support before the Pd-film during the permeation process. Similarly, the effect of using sweep gas is more significant when applied on the side where the Pd-film is placed. Besides, both membranes showed good mechanical stability for around 200 h, obtaining a complete H 2 /N 2 ideal separation factor for the entire set of experiments. At this point, this value decreased up to around 400 for the membrane prepared with raw TiO 2 particles as intermediate layer (TiO 2 /Pd). At the same time, complete selectivity was maintained up to 1000 h in case of using doped TiO 2 particles (Pd–TiO 2 /Pd). However, a specific decrease in the H 2 -permeate flux was found while operating at 450 °C due to a possible alloy between palladium and titanium that is not formed at a lower temperature (400 °C). Therefore, Pd–TiO 2 /Pd membranes prepared by Electroless Pore-Plating could be very attractive to be used under stable operation in either independent separators or membrane reactors in which moderate temperatures are required. • Pd-doped titania highly reduces the Pd-thickness for reaching fully dense membranes. • TiO 2 barriers yield H 2 permeance up to 4.17·10 −4 mol/s m 2 Pa 0.5 and complete α H2/N2 . • Pd-doped titania allows stability for long-time operation up to 1000 h at 400 °C. • Temperature above 450 °C leads to certain PdTi alloy and H 2 permeance decrease.

Microscopic insight into the structure of negative parity yrast bands in 99−117Pd isotopes

The negative parity bands in the odd-mass Palladium (Pd) nuclei in mass region A ∼110 are known to be built on the deformation-driving h11/2 neutron orbital. They offer rich testing grounds for the present day models as well as provide good base to study the deformation systematics of this mass region along with the other nuclear structure properties. Motivated by this, we have taken up the study of odd-mass isotopic chain of 99−117Pd by applying the theoretical framework of the Projected Shell Model. The results are obtained for the negative parity yrast cascades in these nuclei as well as the on the reduced electric transition probabilities. The quasi-particle structure of these bands has been understood in terms of the band diagrams in which the rotational phenomenon like band-crossing is also discussed. The E-GOS plots along with the R2/1 and R3/2 ratios predict the quasi-deformed structure for these bands.

Electrodeposition of Palladium Nanoparticles on Carbon Nanotubes Dispersed in an Ionic Liquid

Electrodeposition of palladium nanoparticles (PdNPs) was investigated on single walled carbon nanotubes (SWCNTs) or few walled carbon nanotubes (FWCNTs) dispersed in 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide (BMPTFSA) containing [PdBr4]2 -. Ionic liquids have been expected to be alternative electrolytes for electrodeposition of various metals and alloys because of such unique characteristics as wider electrochemical potential window, negligible vapor pressure, less flammability, and wider usable temperature range, compared with conventional organic electrolytes. In addition, the ionic liquids have been known to have ability to disperse nanoparticles without any additives[1]. Although several studies have reported the preparation of metal nanoparticles by electrochemical cathodic reduction in ionic liquids, there are some problems in the utilization of the nanoparticles dispersed in ionic liquids. Platinum nanoparticles (PtNPs) prepared in ionic liquids have been reported to be collected on such carbon materials as carbon nanotubes (CNTs) and carbon black with elevating temperature[2,3]. It has been reported that CNTs are dispersed in ionic liquids and act as an electrode[4]. We have already reported the electrodeposition of PtNPs is possible on CNTs dispersed in BMPTFSA containing [PtBr4]2–[5]. The average particle size of the PtNPs was 1.7 nm, which was independent on the concentration of [PtBr4]2– and the kind of CNTs. In the present study, the electrodeposition of PdNPs was investigated on SWCNTs and FWCNTs dispersed in BMPTFSA containing [PdBr4]2– in order to examine the effect of the deposition potential on the average particle size of PdNPs because the deposition potential of Pd is more positive than that of Pt[3,6]. In addition, the effect of the catalyst remaining in CNTs on electrodeposition of PdNPs was examined using high purity (> 99.6% purity) FWCNT synthesized by the fluidized bed method[7].Galvanostatic cathodic reduction was conducted in BMPTFSA containing CNTs and [PdBr4]2– at room temperature, resulted in deposition of NPs, which were identified as metallic Pd by energy dispersive X-ray analysis (EDX) and transmission electron mocroscopy (TEM). The average potential of [PdBr4]2– during the galvanostatic cathodic reduction was –1.2 V, which was close to that reported on a planar glassy carbon electrode[6]. Potentiostatic cathodic reduction at different potentials indicated that the average particle size of PdNPs decreased with lowering the potential. Pd nuclei are considered to occur and grow on the CNTs dispersed in the ionic liquid. As the potential becomes more negative, the cations of the ionic liquid are expected to be accumulated on the surface of the nuclei and CNTs in order to compensate the excess negative charge. The cations strongly attracted on the surface are considered to inhibit the growth of the PdNPs and affect their average particle size. On the other hand, the remaining catalyst in the CNTs was found to have little effect on the average particle size of PdNPs.

N = Z even–even proton-rich nuclei and nuclear structure

Nuclear systems near nucleon drip lines have great importance in studying nucleon–nucleon force properties. However, such unstable systems have few experimental data. Due to technical development in recent years, new experimental data assembly provides huge information to analyze possible observation of new phenomena. In the aim of exploring proton-rich nuclei near closed shells, we have studied the even–even Z = N nuclei in $$28<Z<50$$ , $$50<N<82$$ mass region. This study is based on the investigation of the core polarization and the monopole effect originated from the interactions between the magic core and the valence nucleons. In this context, this work includes the calculation of the energy spectra of Zr, Mo, Ru, Pd and Cd nuclei. These calculations were performed in the framework of the nuclear shell model using NuShellX@MSU code. Using recent single-particle energies, the three-body effect consideration introduces some modifications on the effective interaction. By means of the modified interaction, some nuclear properties of the studied nuclei have been evaluated. The results show a reasonable agreement with the available experimental data. The monopole effect is an important component of nucleon–nucleon interaction, in which its consideration gives a reasonably agreement with available data.

Pre-activation of SBA-15 intermediate barriers with Pd nuclei to increase thermal and mechanical resistances of pore-plated Pd-membranes

Thermal and mechanical resistances of palladium composite membranes prepared by Electroless Pore-Plating (ELP-PP) and containing SBA-15 as intermediate layer were improved by doping the silica material with Pd nuclei before its incorporation on the composite membrane. Textural properties of synthesized SBA-15 materials (both raw and doped ones) were analyzed by XRD, N2 adsorption-desorption at 77 K and TEM, while the main properties of the composite membrane were determined by SEM and gravimetric analyses. Moreover, membrane permeation tests were also carried out with pure gases, hydrogen and nitrogen, and binary mixtures of them at temperature of 400 °C and pressure driving forces in the range of 0.5–2.5 bar. The use of bare SBA-15 intermediate layer leads to the appearance of cracks on the Pd layer during permeation experiments at high temperature. In contrast, the use of Pd-doped SBA-15 particles avoids this problem, thus improving both thermal and mechanical resistances of the composite ELP-PP Pd-membrane. Following this preparation method, an estimated Pd thickness of 7.1 μm was obtained, reaching a hydrogen permeance of 3.81·10−4 mol s−1 m−2 Pa−0.5 and ensuring an ideal H2/N2 separation factor higher than 2550 at 400 °C.

Triaxiality-related nuclear phenomena in the A ≈ 100 mass region

Solid experimental evidence for triaxial nuclear shape is difficult to obtain and is quite rare. Such evidence can be provided by the phenomena of chiral rotation and wobbling motion, as these can occur only in triaxially deformed nuclei. Although nuclear chirality is well documented in different mass regions, experimental evidence for multiple chiral bands as well as for wobbling motion has been reported so far only in a few nuclei. Pd and Rh nuclei in the A ≈ 100 mass region have been recently studied, and transverse wobbling motion as well as multiple chiral band structures were identified for the first time in this region. These observations provide experimental evidence for the predicted triaxial shape in this mass region, and new data which enable a better understanding of the studied phenomena.

Rotational bands in neutron-rich Mo, Ru, and Pd nuclei * * Supported by the National Key R&D Program of China (2018YFA0404401), the National Natural Science Foundation of China (11835001, 11575007, 11847203) and the China Postdoctoral Science Foundation (2018M630018)

The collective rotations of the configuration in neutron-rich Mo, Ru and Pd isotopes were systematically investigated by the configuration-constrained cranking shell model based on the Skyrme Hartree-Fock method with pairing treated by shell-model diagonalization. The calculations efficiently reproduce the experimental moments of inertia of both the ground-state and side bands. Rotational bands built on two-particle configurations have been the subject of intense study. Possible configurations were assigned to the observed bands in 102-106Mo, 108-112Ru and 112-114Pd. We predict the existence of the bands in 108,110Mo. These results provide deep insights into the structure of neutron-rich nuclei, and provide useful information for future experiments.

Shape coexistence and collective low-spin states in Sn112,114 studied with the (p,p′γ) Doppler-shift attenuation coincidence technique

Proton-scattering experiments followed by the coincident spectroscopy of $\gamma$ rays have been performed at the Institute for Nuclear Physics of the University of Cologne to excite low-spin states in $^{112}$Sn and $^{114}$Sn, to determine their lifetimes and extract reduced transitions strengths $B(\Pi L)$. The combined spectroscopy setup SONIC@HORUS has been used to detect the scattered protons and the emitted $\gamma$ rays of excited states in coincidence. The novel $(p,p'\gamma)$ DSA coincidence technique was employed to measure sub-ps nuclear level lifetimes. 74 level lifetimes $\tau$ of states with $J = 0 - 6$ were determined. In addition, branching ratios were deduced which allowed the investigation of the intruder configuration in both nuclei. Here, $sd$ IBM-2 mixing calculations were added which support the coexistence of the two configurations. Furthermore, members of the expected QOC quintuplet are proposed in $^{114}$Sn for the first time. The $1^-$ candidate in $^{114}$Sn fits perfectly into the systematics observed for the other stable Sn isotopes. The $E2$ transition strengths observed for the low-spin members of the so-called intruder band support the existence of shape coexistence in $^{112,114}$Sn. The collectivity in this configuration is comparable to the one observed in the Pd nuclei, i.e. the 0p-4h nuclei. Strong mixing between the $0^+$ states of the normal and intruder configuration might be observed in $^{114}$Sn. The general existence of QOC states in $^{112,114}$Sn is supported by the observation of QOC candidates with $J \neq 1$.

Fabrication of palladium-copper nanoparticles with controllable size and chemical composition

A series of PdxCu100−x (x = 20, 40, 60, 80) particles with the sizes of 7–9 nm were fabricated by a two-step polyol reduction process, which differentiated the nucleation and growth steps of the nanoparticles. The primary reduction of Pd2+ by ethylene glycol at 393 K formed appreciable amounts of Pd0 nuclei, while the subsequent reduction at 473 K fully reduced the Pd2+ and Cu2+ species with the aid of the initially formed Pd nuclei seeds. Meanwhile, the releasing oleylamine, previously coordinated with metal cations, acted as the capping agent to segregate the nanoparticles. Both parameters simultaneously controlled the assembly kinetics of the bimetallic nanoparticles and resulted in uniform sizes and designed chemical compositions. Among them, the Pd80Cu20 nanoparticles showed quite promising activity and selectivity for the hydrogenation of nitrobenzene under mild conditions.

A Facile and Environmentally Friendly One-Pot Synthesis of Pt Surface-Enriched Pt-Pd(x)/C Catalyst for Oxygen Reduction

Platinum surface-enriched bimetallic PtPd nanoparticles are synthesized via a facile and eco-friendly approach. Significantly different formation processes of single Pt, Pd, and bimetallic PtPd nanoparticles under various conditions have been monitored by UV-visible spectra. The size of the bimetallic Pt-Pd nanoparticles has been found to be significantly affected by the pH of the starting precursor solutions. Uniform bimetallic Pt-Pd nanoparticles with an average diameter of ~3 nm are formed in the basic solutions; however, the particle size can be as large as 11 nm when synthesized in acidic media. The detailed morphology, composition, and structure of the carbon-supported bimetallic Pt-Pd electrocatalysts have been extensively characterized and correlated with their electrochemical properties as evaluated using cyclic voltammetry and single-cell test. The formation of Pt surface-enriched Pt-Pd bimetallic nanoparticles has been confirmed by X-ray photoelectron spectroscopy and has been interpreted by the exclusively reduced Pt around the newly formed Pd nuclei due to the catalytic action of Pd, which in turn curbs the unfavorable growth of the bimetallic nanoparticles. The electrochemical tests indicate that the optimized Pt-Pd/C with reduced cost exhibits competitive catalytic performance toward oxygen reduction reaction and superior tolerance to methanol over the state-of-the-art Pt/C.

Dinuclear fused salen complexes of group-10 metals: Peculiarity of the crystal structure and near-infrared luminescence of a bis(Pt-salen) complex

Dinuclear fused salen complexes with Ni, Pd, and Pt nuclei were synthesized, and their crystal structures were determined. In the crystal structure of the Pt complexes, the molecules were virtually planar and formed a closely stacked dimer every two molecules, whose Pt---Pt interatomic distance was 3.43Å. The absorption spectra of the dinuclear salen complexes were similar to each other both in solution and in the solid state. The dinuclear Pt complex exhibited photoluminescence, presumably related to the π-conjugated system of the naphthalene ring, both in solution and in the solid state. The low-energy emission, corresponding to a longer wavelength compared to that of analogous mononuclear complexes, ranged to the near-infrared region, suggesting that the naphthalene ring is perturbed by the adjoining chelate rings as if these moieties formed a fused aromatic ring system.

All-metal aromatic cationic palladium triangles can mimic aromatic donor ligands with Lewis acidic cations.

We present that cationic rings can act as donor ligands thanks to suitably delocalized metal-metal bonds. This could grant parent complexes with the peculiar properties of aromatic rings that are crafted with main group elements. We assembled Pd nuclei into equilateral mono-cationic triangles with unhindered faces. Like their main group element counterparts and despite their positive charge, these noble-metal rings form stable bonding interactions with other cations, such as positively charged silver atoms, to deliver the corresponding tetranuclear dicationic complexes. Through a mix of modeling and experimental techniques we propose that this bonding mode is an original coordination-like one rather than a 4-centre-2-electron bond, which have already been observed in three dimensional aromatics. The present results thus pave the way for the use of suitable metal rings as ligands.

E0 transitions in 106Pd: Implications for shape coexistence

Level lifetimes in 106Pd were measured with the Doppler-shift attenuation method following inelastic neutron scattering, and electric monopole transition strengths between low-lying 2+ states were deduced. The large \( \rho^{2}\)(E0) values obtained provide evidence for shape coexistence, extending observation of such structures in the N = 60 isotones. Included in these results is the first determination of the E0 transition strength in the Pd nuclei between levels with K = 2 .

Electroless Plating of Pd on Macro-Porous Alumina Support for H&lt;sub&gt;2&lt;/sub&gt; Purification

In this work, Pd metal layer was deposited on in-house prepared macro-porous disc alumina support by electroless plating. The in-house prepared support were repeatedly seeded for 4 cycles to obtain Pd nuclei before repeatedly electroless plated for 4 cycles. The 4-cycle Pd plating was to obtain the full layer of Pd metal observing from changing support surface from black to light grey. The plated membrane samples were annealed at 550 and 600oC for using in high-temperature H2 separation. The annealed samples were observed morphology by SEM and confirm the occurrence of Pd layer with EDS. The SEM images revealed incomplete Pd layer. The over 4 cycles of plating were needed to form complete Pd layer since the numerous Pd ions diffused into macro-pores alumina support instead of depositing on the surface of macro-porous support. The higher annealing temperature of 600oC led to denser layer of Pd with the presence of small cracks due to the contraction of Pd particles.

Nucleation and Growth Behaviors of Pd Catalyst and Electroless Ni Deposition on Cu (111) Surface

The electroless nickel plating process was used for protecting the copper pad of printed circuit boards from oxidation, which needs Pd catalytic treatment on the copper surface before Ni growth. The quantity of Pd deposition had a linear relationship with the activation time, while the Ni growth on the Pd-activated Cu films was accelerated with the deposition time by auto-catalytic reaction. It was confirmed that both Pd and Ni were grown coherently on the Cu (111) plane based on the high-resolution TEM measurement. The in-plane lattice misfits of Pd (111) and Ni (111) to Cu (111) are 7.6% (compressive) and 2.5% (tensile), respectively. The Pd grew in a dot-like rather than a two-dimensional form due to the large lattice mismatch. In addition, the lattice mismatch of Ni (111) to Pd (111) is 9.4% (tensile), and the larger lattice misfit seems to make it difficult for the Ni to nucleate on the Pd nuclei. It can be deduced that the Pd works simply as an electron supplier by oxidizing a reducing agent and the Ni reduction occurs preferably on the Cu surface by an electron from the Pd.

Lifetime measurement for the possible antimagnetic rotation band inPd101

Lifetime measurements were made for the $\ensuremath{\nu}{h}_{11/2}$ band in $^{101}\mathrm{Pd}$, which had been interpreted as a possible antimagnetic rotation band based on the comparison of $I\ensuremath{-}\ensuremath{\omega}$ behavior with the calculation of a semiclassical particle-rotor model in our previous study. Doppler broadened line shapes were analyzed for the decaying $\ensuremath{\gamma}$ rays in the band following the reaction $^{68}\mathrm{Zn}(^{37}\mathrm{Cl},\phantom{\rule{0.16em}{0ex}}\text{1p3n})^{101}\mathrm{Pd}$. The semiclassical particle-rotor model was modified to reproduce both the $I\ensuremath{-}\ensuremath{\omega}$ plot and the $B(E2)$ behavior simultaneously for the antimagnetic rotation bands in Pd and Cd nuclei, for which $B(E2)$ values had been measured so far. Reasonable agreements between the experiment and the calculation were obtained. It is concluded that the lower part of the $\ensuremath{\nu}{h}_{11/2}$ band in $^{101}\mathrm{Pd}$ can be interpreted as an antimagnetic rotor.