Spin-orbit Components Research Articles

Ab-initio study of spin-orbit effect on 175Lu19F spectroscopy

By ab-initio methods, the spin-orbit coupling effects of Lu on the low-lying electronic states of 175Lu19F are calculated. Thus, allowing for the first time the prediction of the nine observed transition systems in a very good agreement. This is ensured by calculating the fine structure which is consisted of 36 Ω(±) states and situated below 48000 cm−1. The potential energy curves (PECs) of these states are plotted in a range of internuclear distance from 1.30 Å to 4.40 Å and their spectroscopic constants (Re, Te, ωe, ωeχe) are determined. The main parent of these spin-orbit components (SOC) is determined by the percentage composition in term of Λ-S states. Moreover, the splitting energies between Ω(±) states are calculated and the Hund case to which LuF belongs is discussed.

Electronic bands of scandium monocarbide, ScC, in the region 14 140-16 000 cm-1.

Scandium monocarbide molecules, ScC, have been prepared by the reaction of 532 nm laser-ablated Sc metal with acetylene or methane under supersonic jet-cooled conditions. Electronic spectra of Sc12C and Sc13C have been recorded in the region 14 140-16 000 cm-1 using laser-induced fluorescence, and about 40 bands of each isotopomer have been analyzed rotationally. Wavelength resolved emission spectra have been obtained for many of them. The results show that Sc12C has a 2Πi ground state, with a bond length of 1.952 Å. Its vibrational frequency and spin-orbit coupling constant are 648 cm-1 and -39.47 cm-1, respectively (631 cm-1 and -39.32 cm-1 in Sc13C). Lying 155.58 cm-1 above the X2Π3/2 level (154.72 cm-1 in Sc13C) is a 4Π5/2 level, the lowest spin-orbit component of a 4Πi state. The excited states at higher energy are very complicated. Bands from both the doublet and quartet spin manifolds are present, and there are strong doublet-quartet interactions which induce many nominally-forbidden bands violating the selection rule ΔS = 0. Eight excited electronic states have been recognized, including four 4Δ states. These 4Δ states represent four of the five 4Δ states from the electron configurations (C 2pσ)2 (C 2pπ)2 (Sc 3dδ)1 and (C 2pσ)1 (C 2pπ)2 (Sc 4sσ)1 (Sc 3dδ)1.

Qbar{Q} (Qin {b, c}) spectroscopy using the Cornell potential

The mass spectra and decay properties of heavy quarkonia are computed in nonrelativistic quark-antiquark Cornell potential model. We have employed the numerical solution of Schrödinger equation to obtain their mass spectra using only four parameters namely quark mass (m_c, m_b) and confinement strength (A_{cbar{c}}, A_{bbar{b}}). The spin hyperfine, spin-orbit and tensor components of the one gluon exchange interaction are computed perturbatively to determine the mass spectra of excited S, P, D and F states. Digamma, digluon and dilepton decays of these mesons are computed using the model parameters and numerical wave functions. The predicted spectroscopy and decay properties for quarkonia are found to be consistent with available data from experiments, lattice QCD and other theoretical approaches. We also compute mass spectra and life time of the B_c meson without additional parameters. The computed electromagnetic transition widths of heavy quarkonia and B_c mesons are in tune with available experimental data and other theoretical approaches.

Photocatalytic activity and microstructure of micro-arc oxidized TiO2:Cr3+ composite coatings

ABSTRACTIn this study, the TiO2:Cr3+ composite coatings were formed in phosphate-based electrolyte with the addition of Cr2O3 by micro-arc oxidation (MAO) treatment. The chemical and physical properties of coatings were investigated. The results showed that the TiO2:Cr3+ coatings are mainly composed of Ti, O, P and Cr. And the Cr content in the coatings increased with the MAO treatment time. XRD results showed the TiO2:Cr3+ coatings are composed of anatase phase and anatase content varied with the treatment time. XPS results indicated that Ti2p spin-orbit components of the TiO2:Cr3+ coatings are shifted towards higher binding energy, compared with the pure TiO2 coating, suggesting that some of the Cr3+ ions are incorporated into TiO2 lattice. The photocatalytic experiment results showed that the TiO2:Cr3+ coatings are of higher photocatalytic activity than that of the pure TiO2 coatings. Besides, the Cr3+ is of positive effect on photocatalytic properties of TiO2:Cr3+ coatings.

Mass spectra and decay properties of the $c\bar{c}$ c c ¯ meson

In this article we present the result of $c\bar{c}$ meson mass calculation by solving the Schrodinger equation numerically considering the Coulomb plus linear potential. The spin-hyperfine, spin-orbit and tensor components of one-gluon-exchange interactions are employed to obtain the mass spectra of $c\bar{c}$ meson. The calculated mass spectra are compared with the latest results of PDG and are found to be in good accordance. The Regge trajectories of the calculated mass spectra have also been constructed. The values of the wave function are extracted and employed to calculate the leptonic decay constant, $\gamma\gamma$ , gg, $e^{+}e^{-}$ , light hadron (LH) and $\gamma\gamma\gamma$ decay widths of S-wave $0^{-+}$ and $1^{- -}$ states of $c\bar{c}$ meson, the widths have been calculated by Van Royen-Weisskopf formula and by NRQCD mechanism incorporating relativistic corrections of order $\nu^{2}$ . The $\gamma\gamma$ and gg decay widths of $\chi_{0}$ and $\chi_{2}$ states of $c\bar{c}$ meson have also been calculated. The calculated decay constants and widths have been compared with the experimental results.

Observation of low-lying electronic states of NiD with multi-isotope analysis

Resolved laser induced fluorescence spectra of 58NiD, recorded at Doppler resolution between 11000 and 18000 cm−1 have established >200 term energies in two of the three strongly interacting, low-lying states (2Δ, 2Π, 2Σ+) of NiD, associated with an Ni+(3d9)D− configuration. Our observations span v = 0–5 in the lowest spin–orbit component of the ground state, X 2Δ5/2, v = 0–3 in X 2Δ3/2 and v = 0–1 in the lower component of the W 2Π3/2 state. Collisional processes populate several neighbouring excited states, allowing us also to locate the first rotational levels of A(Ω = 5/2) v = 1, I(Ω = 3/2) v = 0 and E(Ω = 3/2) v = 1 at 16664.8, 17367.3 and 17508.1 cm−1 respectively. Spin-orbit and rotation-electronic interactions are strong in NiD (as in NiH), and with no direct observation of either of the Ω = 1/2 states, meaningful representations of the low-lying energy levels is difficult. We have therefore attempted a global, multi-isotope fit to reproduce the term energies of the known term energies of NiD and 58,60,62NiH (where some Ω″ = 1/2 levels are known). Dunham-type parameters have been used to represent the unperturbed 2Δ, 2Π and 2Σ+ states, with off-diagonal matrix elements (treating spin–orbit, L- and S-uncoupling effects) based on Ni+ atomic properties. Born-Oppenheimer breakdown terms were included in the model. The equilibrium bond lengths for 58NiH/58NiD are 1.4545(1)/1.4559(1) Å for the X 2Δ state and 1.5094(2)/1.5083(2) Å for the W 2Π state.

Study on photocatalytic performance of TiO2 and Fe3+/TiO2 coatings

ABSTRACTThe TiO2 coatings were fabricated in phosphate-based electrolyte on pure titanium by micro-arc oxidation (MAO); then, they were impregnated with Fe3+-containing electrolyte to produce the Fe3+/TiO2 composite coatings. The physical and chemical properties of two coatings were investigated by SEM, XRD, AFM, XPS and EDS. A UV–vis spectrophotometer was also used to study photocatalytic properties of the coatings. It is indicated that the coating formed in phosphate-based electrolyte were composed of anatase and rutile phase with varying fraction depending on the applied frequency. XPS results revealed that Ti 2p spin-orbit components of Fe3+/TiO2 composite coatings are shifted towards higher binding energy, with respect to TiO2 coatings, suggesting that some of the Fe3+ ions are incorporated into TiO2 lattice. The Fe3+/TiO2 composite coatings showed an obvious enhanced photocatalytic activity than that of the TiO2 coating under irradiation.

Investigation of earth-alkaline (EA = Mg, Ca, Sr) containing methylammonium tin iodide perovskite systems

Methylammonium tin iodide systems containing earth-alkaline ions (CH3NH3Sn1−x (EA) x I3, EA = Ca2+, Sr2+, Mg2+, 0 ≤ x ≤ 0.30) were investigated. The X-ray diffraction patterns detected the formation of tetragonal nearly cubic CH3NH3SnI3 (space group P4mm), SnI2, and not identified phases. The morphological analysis confirmed the presence of secondary phases with formation of irregularly shaped crystallites. The Sn3d and I3d photoemission spectra revealed the typical position and separation of spin–orbit components for Sn2+ in halides. Static thermogravimetric measurements (T = 85 °C) showed a barely measurable weight loss for EA = Mg, a dramatic decrease of the weight loss rate for EA = Ca, and recorded weight losses till t ≈ 1.5 h only for EA = Sr, respectively. The optical spectra displayed absorption edges which increased at increasing the (EA)-content with maximum values for x = 0.050 (λ on-set = 1754 nm, EA = Mg; λ on-set = 1692 nm, EA = Ca; and λ on-set = 1338 nm, EA = Sr, respectively). The Tauc plots revealed a direct semiconducting behavior with band energy gaps depending on the nature and amount of the (EA)-ions. The photoluminescence (PL) spectra showed, for EA = Mg, an increase of the PL-band intensity at increasing the Mg content with a maximum at x = 1.0 and, for EA = Ca, an increase of band intensity at increasing the Ca-content and for EA = Sr, a band intensity maximum at x = 0.025. This was explained by the similar ionic radius between Sn2+ and Sr2+ ions which can be easily exchanged in the SnI6 2− octahedra.

Kaon-nucleon scattering states and potentials in the Skyrme model

We study the (anti)kaon nucleon interaction in the Skyrme model. The kaon field is introduced as a fluctuation around the rotating Skyrmion for the nucleon. As an extension of our previous work, we study scattering states and examine phase shifts in various kaon-nucleon channels. Then we study the interaction, where we find that it consists of central and spin-orbit components for isospin channels, $I = 0, 1$, with energy dependence and nonlocality. The interaction is then fitted to a Shr\"odinger equivalent local potential for s- and p-waves.

ExoMol molecular line lists – XXIII. Spectra of PO and PS

Comprehensive line lists for phosphorus monoxide ($^{31}$P$^{16}$O) and phosphorus monosulphide ($^{31}$P$^{32}$S) in their $X$ $^2\Pi$ electronic ground state are presented. The line lists are based on new ab initio potential energy (PEC), spin-orbit (SOC) and dipole moment (DMC) curves computed using the MRCI+Q-r method with aug-cc-pwCV5Z and aug-cc-pV5Z basis sets. The nuclear motion equations (i.e. the rovibronic Schr\"odinger equations for each molecule) are solved using the program Duo. The PECs and SOCs are refined in least-squares fits to available experimental data. Partition functions, $Q(T)$, are computed up to $T=$ 5000 K, the range of validity of the line lists. These line lists are the most comprehensive available for either molecule. The characteristically sharp peak of the $Q$-branches from the spin-orbit split components give useful diagnostics for both PO and PS in spectra at infrared wavelengths. These line lists should prove useful for analysing observations and setting up models of environments such as brown dwarfs, low-mass stars, O-rich circumstellar regions and potentially for exoplanetary retrievals. Since PS is yet to be detected in space, the role of the two lowest excited electronic states ($a$ $^4\Pi$ and $B$ $^2\Pi$) are also considered. An approximate line list for the PS $X - B$ electronic transition, which predicts a number of sharp vibrational bands in the near ultraviolet, is also presented. he line lists are available from the CDS (cdsarc.u-strasbg.fr) and ExoMol (www.exomol.com) databases.

Electrical, Thermal and Spectroscopic Characterization of Bulk Bi2Se3 Topological Insulator

We report the electrical (angular magnetoresistance and Hall), thermal (heat capacity) and spectroscopic (Raman, X-ray photoelectron, angle-resolved photoelectron) characterization of a bulk Bi2Se3 topological insulator, which was grown by self-flux method through solid-state reaction from high-temperature (950. degrees C) melt and slow cooling (2. degrees C/h) of constituent elements. Bi2Se3 exhibited metallic behaviour down to 5 K. Magnetotransport measurements revealed linear up to 400 and 30% magneto-resistance (MR) at 5 K under a 14-T field in perpendicular and parallel field directions, respectively. We noticed that the MR of Bi2Se3 is very sensitive to the angle of the applied field. The MR is maximum when the field is normal to the sample surface, while it is minimum when the field is parallel. The Hall coefficient (RH) is seen nearly invariant with a negative carrier sign down to 5 K albeit having near-periodic oscillations above 100 K. The heat capacity (C-p) versus temperature plot is seen without any phase transitions down to 5 K and is well fitted (Cp =gamma T + beta T-3) at low temperature with a calculated Debye temperature (theta(D)) value of 105.5 K. Clear Raman peaks are seen at 72, 131 and 177 cm(-1) corresponding to A(1g)(1), E-g(2) and A(1g)(2), respectively. Though two distinct asymmetric characteristic peak shapes are seen for Bi 4f(7/2) and Bi 4f(5/2), the Se 3d region is found to be broad, displaying the overlapping of spin-orbit components of the same. Angle-resolved photoemission spectroscopy (ARPES) data of Bi2Se3 revealed distinctly the bulk conduction bands (BCB), surface state (SS), Dirac point (DP) and bulk valence bands (BVB), and 3D bulk conduction signatures are clearly seen. Summarily, a host of physical properties for the as-grown Bi2Se3 crystal are reported here.

Microstructure and photocatalytic property of TiO2 and Fe3 +:TiO2 films produced by micro-arc oxidation

First, the TiO2 films prepared by micro-arc oxidation (MAO) were formed in phosphate based electrolyte on pure titanium; after that, they were impregnated with Fe3+-containing electrolyte to produce the Fe3+:TiO2 composite films. Effects of the applied current density and impregnation time and concentration on physical and chemical properties of TiO2 and Fe3+:TiO2 composite films were investigated by Scanning electron microscopy (SEM), stereoscopic microscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray spectroscopy (EDS). A UV–vis spectrophotometer was also used to study photocatalytic properties of both films. It is indicated that the film formed in phosphate-based electrolyte were composed of anatase phase with varying fraction depending on the applied current density. XPS results revealed that Ti2p spin-orbit components of Fe3+:TiO2 composite films are shifted towards higher binding energy, with respect to TiO2 films, suggesting that some of the Fe3+ ions are incorporated into TiO2 lattice. Photocatalytic activity of the films was studied by measuring the degradation rate of methylene blue on their surface under simulated sunlight irradiation. The Fe3+:TiO2 composite films showed an obvious enhanced photocatalytic activity than the pure layers under UV-irradiation, while their photocatalytic degradation was much higher than that of the TiO2 film under the irradiation.

Nephelauxetic effect in the lanthanide complexes with methyl acetoacetate

ABSTRACTThe complexation between methyl acetoacetate and certain lanthanides was studied in the mixed ethanol–water solvent (90% ethanol) using electronic absorption spectroscopy. The formation of the cationic 1:2 type complexes was shown at alkalescent medium. Based on the energy of the f–f transitions, the interelectronic repulsion parameters (Slater integrals) were determined by a least-square fit using effective Hamiltonian comprised of electrostatic and spin–orbit components and the nephelauxetic ratio was calculated as a ratio of the second-order Slater integrals. The nephelauxetic ratio was found to be proportional to the relative shortening of the lanthanide–oxygen bond length when the geometry of the complexes was optimized by semiempirical Sparkle/Parametric Method 7.

Analysis of the oxidation state of platinum particles in supported catalysts by double differentiation of XPS lines

In the work the double differentiation of functions describing the Pt4f7/2 band in the XPS spectra of model supported Pt/SiO2 catalysts is performed in order to determine the number of different chemical states of platinum particles. The functions for the differentiation are obtained by the deconvolution of the experimental spectral contour into two spin-orbit components. As a result of the performed analysis of the number and position of the minima of the second derivative of the function of Pt437/2 the conditions of the oxidation of platinum particles in the Pt/SiO2 sample on treating in a NO + O2 mixture and the reduction of platinum oxide particles on interacting of the PtOx/SiO2 sample with hydrogen are determined.

Elastic versus inelastic spin-polarized electron scattering from a ferromagnetic surface

Spin-polarized electron energy loss spectroscopy was applied to study the intensity asymmetry upon the reversal of the incident spin polarization of elastically and inelastically scattered polarized electrons from an epitaxial ferromagnetic Fe layer on W(110). The polarization of the incident beam was always collinear with the magnetic moment (magnetization) of the sample, and the asymmetries were measured for two opposite magnetizations of the sample. They allowed extracting the exchange and the spin-orbit components from the measured asymmetry. A strong asymmetry of Stoner excitations in an Fe film on W(110) is observed, as expected, at about 3 eV energy loss. The value of the asymmetry declines but is still observable when the surface is contaminated. The asymmetry of elastic scattering for normal incidence and a 50\ifmmode^\circ\else\textdegree\fi{} detection angle is close to zero in contrast to the Stoner excitation asymmetry (inelastic scattering). However, the asymmetry of elastic scattering increases substantially at two specular geometries with 25\ifmmode^\circ\else\textdegree\fi{} and 72\ifmmode^\circ\else\textdegree\fi{} angles of incidence, compared to the normal incidence, and may be even larger than the asymmetry of Stoner excitations. The sign of elastic scattering asymmetry changes upon the reversal of the sample magnetization, indicating the magnetic origin of this asymmetry, i.e., spin-dependent electron-electron scattering with electron exchange. The calculation of the asymmetry of elastic spin-polarized electron scattering from a spin-dependent surface potential barrier shows a qualitative agreement with the measurements.

Infrared spectroscopy of molecular ions in selected rotational and spin-orbit states.

First results are presented obtained with an experimental setup developed to record IR spectra of rotationally state-selected ions. The method we use is a state-selective version of a method developed by Schlemmer et al. [Int. J. Mass Spectrom. 185, 589 (1999); J. Chem. Phys. 117, 2068 (2002)] to record IR spectra of ions. Ions are produced in specific rotational levels using mass-analyzed-threshold-ionization spectroscopy. The state-selected ions generated by pulsed-field ionization of Rydberg states of high principal quantum number (n ≈ 200) are extracted toward an octupole ion guide containing a neutral target gas. Prior to entering the octupole, the ions are excited by an IR laser. The target gas is chosen so that only excited ions react to form product ions. These product ions are detected mass selectively as a function of the IR laser wavenumber. To illustrate this method, we present IR spectra of C2H2 (+) in selected rotational levels of the (2)Πu,3/2 and (2)Πu,1/2 spin-orbit components of the vibronic ground state.

Roles of NN-interaction components in shell-structure evolution

Since the importance of the monopole interaction was first emphasized in 1960s, roles of monopole strengths of two-body nucleon–nucleon interaction in shell structure have been discussed. Through the monopole strengths, we study the roles in shell-structure evolution, starting from explicit forms of the interaction. For the tensor component of the interaction, we show the derivation of the relation, (2j>+1)Vjj>+(2j<+1)Vjj<=0, with a detailed manipulation. We show that one-body spin–orbit term appears in the multipole expansion of two-body spin–orbit interaction. Only the spin–orbit components can affect the spin–orbit energy splitting between spin–orbit partners, when the spin–orbit partner orbits are fully occupied.

Tetraquark states in the bottom sector and the status of the $$Y_b$$ Y b (10890) state

We have done the exploratory study of bottom tetraquarks ($[bq\bar b \bar q];{q\in u,d}$) in the diquark-antidiquark framework with the inclusion of spin hyperfine, spin-orbit and tensor components of the one gluon exchange interaction. Our focus here is on the $Y_b$(10890) and other exotic states in the bottom sector. We have predicted some of the bottom counterparts to the charm tetraquark candidates. Our present study shows that if $Z_b(10610)$ and $Z_b(10650)$ are diquark-diantiquark states then they have to be first radial excitations only and we have predicted $Z_b(10650)$ state as first radial excitation of tetraquark state $X_b$ (10.143-10.230). We have identified $X_b$ state with $J^{PC}= 1^{+-}/0^{++}$ as being the analogue of $Z_c(3900)$. An observation of the $X_b$ will provide a deeper insight into the exotic hadron spectroscopy and is helpful to unravel the nature of the states connected by the heavy quark symmetry. We particularly focus on the lowest P wave $[bq][\bar b\bar q]$ states with $J^{PC}=1^{--}$ by computing their leptonic, hadronic and radiative decay widths to predict the status of still controversial $Y_b$(10890) state. Apart from this, we have also shown here the possibility of mixing of P wave states. In the case of mixing of $1^{--}$ state with different spin multiplicities, we found that predicted masses of the mixed P states differ from $Y_b$(10890) state only by $\pm20$ MeV energy difference which can be helpful to resolve further the structure of $Y_b$(10890).

Band structure characterization of WS2 grown by chemical vapor deposition

Growth by chemical vapor deposition (CVD) leads to multilayer WS2 of very high quality, based on high-resolution angle-resolved photoemission spectroscopy. The experimental valence band electronic structure is considered to be in good agreement with that obtained from density functional theory calculations. We find the spin-orbit splitting at the K¯ point to be 420 ± 20 meV with a hole effective mass of −0.35 ± 0.02 me for the upper spin-orbit component (the branch closer to the Fermi level) and −0.43 ± 0.07 me for the lower spin-orbit component. As predicted by theory, a thickness-dependent increase of bandwidth is observed at the top of the valence band, in the region of the Brillouin zone center. The top of the valence band of the CVD-prepared films exhibits a substantial binding energy, consistent with n-type behavior, and in agreement with transistor characteristics acquired using devices incorporating the same WS2 material.

Decay rates of charmonia within a quark-antiquark confining potential**Supported by Major Research Project NO. F. 40-457/2011(SR), UGC, India

In this work, we investigate the spectroscopy and decay rates of charmonia within the framework of the non-relativistic Schrödinger equation by employing an approximate inter quark-antiquark potential. The spin hyperfine, spin-orbit and tensor components of the one gluon exchange interaction are employed to compute the spectroscopy of the excited S states and a few low-lying P and D waves. The resultant wave functions at zero inter-quark separation as well as some finite separations are employed to predict the di-gamma, di-leptonic and di-gluon decay rates of charmonia states using the conventional Van Royen-Weisskopf formula. The di-gamma and di-leptonic decay widths are also computed by incorporating the relativistic corrections of order v4 within the NRQCD formalism. We have observed that the NRQCD predictions with their matrix elements computed at finite radial separation yield results which are found to be in better agreement with experimental values for both di-gamma and di-leptonic decays. The same scenario is seen in the case when di-gamma and di-leptonic decay widths are computed with the Van Royen-Weisskopf formula. It is also observed that the di-gluon decay width with the inclusion of binding energy effects are in better agreement with the experimental data available for 1S-2S and 1P. The di-gluon decay width of 3S and 2P waves waves are also predicted. Thus, the present study of decay rates clearly indicates the importance of binding energy effects.