Doublet Structure Research Articles

First analysis of the 2ν1 + 3ν3 band of NO2 at 7192.159 cm−1

The first investigation of the very weak 2ν1+3ν3 absorption band of nitrogen dioxide, 14N16O2, located at 7192.1587(1) cm−1 was performed using Fourier-transform incoherent broadband cavity-enhanced absorption spectroscopy (FT-IBBCEAS) in the 7080–7210cm−1 spectral range. The assigned 2ν1+3ν3 lines involve energy levels of the (203) vibrational state with rotational quantum numbers up to Ka=7 and N=47. Furthermore, due to local resonances involving energy levels from the (2,2,2)⇔(2,0,3) and (5,1,0)⇔(2,0,3) states, several transitions were also observed for the 2ν1+2ν2+2ν3 and 5ν1+ν3 dark bands, respectively. The energy levels were satisfactorily reproduced within their experimental uncertainty using a theoretical model which takes explicitly into account the Coriolis interactions between the levels of the (2,0,3) vibrational state and those of (2,2,2) and of (5,1,0). As a consequence, precise vibrational energies, rotational, and coupling constants were achieved for the triad {(5,0,1), (2,2,2), (2,0,3)} of interacting states of 14N16O2. This theoretical model also accounts for the electron spin-rotation resonances within the (2,0,3), (2,2,2) and (5,1,0) vibrational states. However, owing to the limited experimental resolution (∼0.075cm−1), it was not possible to observe the spin-rotation doublet structure. As a consequence, the spin-rotation constants in the {(2,2,2), (2,0,3), (5,1,0)} excited states were maintained fixed to their ground state values in this study. Using these parameters a comprehensive list of line positions and line intensities was generated for the 2ν1+3ν3 band of NO2.

Description of the Rigid Triaxial Deformation at Low Energy in 76Ge with the Proton-Neutron Interacting Model IBM2

We investigate properties of the low-lying energy states for 76Ge within the framework of the proton-neutron interacting model IBM2, considering the validity of the Z = 38 subshell closure 88Sr50 as a doubly magic core. By introducing the quadrupole interactions among like bosons to the IBM2 Hamiltonian, the energy levels for both the ground state and γ bands are reproduced well. Particularly, the doublet structure of the γ band and the energy staggering signature fit the experimental data correctly. The ratios of B(E2) transition strengths for some states of the γ band, and the g factors of the 21+, 22+ states are very close to the experimental data. The calculation result indicates that the nucleus exhibiting rigid triaxial deformation in the low-lying states can be described rather well by the IBM2.

Magnetic resonance identification of hydrogen at a zinc vacancy in ZnO

Hydrogen (H) at a zinc vacancy (VZn) in ZnO is identified by electron paramagnetic resonance (EPR) and electron spin echo envelope modulation (ESEEM). In ZnO irradiated by 2 MeV electrons, a doublet EPR spectrum, labelled S1, is observed. The doublet structure and the accompanying weak satellites are shown to be the allowed and forbidden lines of the hyperfine structure due to the dipolar interaction between an electron spin S = 1/2 and a nuclear spin I = 1/2 of 1H located at a VZn. The involvement of a single H atom in the S1 defect is further confirmed by the observation of the nuclear Zeeman frequency of 1H in ESEEM experiments. We show that at a VZn, H prefers to make a short O–H bond with one O neighbour and is off the substitutional site, forming a low symmetry C1 defect. In this partly H passivated VZn, the unpaired electron localizes on the p orbital of another O neighbour of VZn, and not on the H.

Tunneling of polarized fermions in 3D double wells

We study the tunneling of a spin polarized Fermi gas in a three-dimensional double-well potential, focusing on the time dynamics starting from an initial state in which there is an imbalance in the number of particles in the two wells. Although fermions in different doublets of the double well tunnel with different frequencies, we point out that (incoherent) oscillations of a large number of particles can arise, as a consequence of the presence of transverse degrees of freedom. Estimates of the doublet structure and of the occupation of transverse eigenstates for a realistic experimental setup are provided.

Colloidal Polarization of Yolk/Shell Particles by Reconfiguration of Inner Cores Responsive to an External Magnetic Field

Yolk/shell particles, which were hollow silica particles containing a movable magnetic silica core (MSC), were prepared by removing a middle polystyrene layer from multilayered particles of MSC/polystyrene/silica shell with heat treatment followed by a slight etching with a basic solution. An ac electric field was applied to the suspension of the yolk/shell particles to form pearl chains (1D structure) of yolk/shell particles. Observation with an optical microscope showed that the MSCs in the silica compartment of the pearl chains had a zigzag structure under the electric field. An external magnetic field applied to the suspension could form a novel structure of doublet MSC in the shell compartment of the quasi-pearl chain structure. Application of a magnetic field was also performed for 2D hexagonally close-packed assemblies of the yolk/shell particles, which could two-dimensionally form a doublet structure of MSCs as if they were polarized in the compartment. Switching on/off the magnetic field successfully controlled the positional ordering of cores in the consolidated silica shell.

Ultrastructure of spermatozoa of the Atlantic cod Gadus morhua L. observed by scanning and transmission electron microscopy

The present study on wild caught Atlantic cod Gadus morhua provides a detailed description of the spermatozoa ultrastructure. The spermatozoa of G. morhua are composed of a head (nucleus) with no acrosome, a midpiece and a single flagellum. The total length is 67.69±6.33μm with a lanceolate sperm head that is 2.34±0.26μm long and 1.32±0.26μm wide. The nucleus presents homogeneous condensation of chromatin with few lacunae of decondensed chromatin. The nuclear fossa penetrates over three third of the nuclear axis and is tubiform. The axoneme is composed of a typical 9+2 microtubular doublet structure and is enclosed by the plasma membrane. Central microtubules are absent from the proximal portion of the anterior end of nuclear notch and a distal centriole complex is perpendicular to the axoneme. A group of mitochondria and vesicles is present in the midpiece. The ultrastructure of the Gadidae G. morhua spermatozoon differs from the structures described earlier for other Gadiformes. The unique features may be synapomorphic for marine Gadidae, and may contribute to the study of phylogenetic relationships in teleost fishes, and be a reference for future studies on spermatozoon quality and morphology in fish.

Two Bulky-Decorated Triangular Dysprosium Aggregates Conserving Vortex-Spin Structure

The self-assembly of dysprosium(III) with the tailored chemical modification of the vanillin group affords two decorated Dy(3) compounds, namely, [Dy(3)(μ(3)-OH)(2)(Hpovh(-))(3)(NO(3))(3)(CH(3)OH)(2)H(2)O]·NO(3)·3CH(3)OH·2H(2)O (2) and [Dy(3)(μ(3)-OH)(2)(H(2)vovh(-))(3)Cl(2)(CH(3)OH)(H(2)O)(3)][Dy(3)(μ(3)-OH)(2)(H(2)vovh(-))(3)Cl(2)(H(2)O)(4)]·Cl(4)·2CH(3)OH·2CH(3)CN·7H(2)O (3), where H(2)povh = N-(pyridylmethylene)-o-vanilloylhydrazone and H(3)vovh = N-vanillidene-o-vanilloylhydrazone. Of particular interest is that those two title Dy(3) compounds maintain the peculiar vortex-spin structure of the ground nonmagnetic doublet. Complex 2 displays frequency-dependent slow magnetic relaxation, while 3 still inherits the single-molecule-magnet behavior as the parent Dy(3) prototype. The dissimilar dynamic magnetic behavior originates from the structural differences in light of the coordination environment of Dy(III) ions, which influence the local tensor of anisotropy and crystal-field splitting on each Dy site.

Raman spectroscopy and crystal-field split rotational states of photoproducts CO and H2 after dissociation of formaldehyde in solid argon

Raman signal is monitored after 248 nm photodissociation of formaldehyde in solid Ar at temperatures of 9-30 K. Rotational transitions J = 2 ← 0 for para-H(2) fragments and J = 3 ← 1 for ortho-H(2) are observed as sharp peaks at 347.2 cm(-1) and 578.3 cm(-1), respectively, which both are accompanied by a broader shoulder band that shows a split structure. The rovibrational spectrum of CO fragments has transitions at 2136.5 cm(-1), 2138.3 cm(-1), 2139.9 cm(-1), and 2149 cm(-1). To explain the observations, we performed adiabatic rotational potential calculations to simulate the Raman spectrum. The simulations indicate that the splitting of rotational transitions is a site effect, where H(2) molecules can reside in a substitution site, in addition to an interstitial site. In the former site, rotational motion is unperturbed by the electrostatic field of the host atoms, while the latter site splits the excited rotational manifolds, J = 2 and 3, into doublet and triplet structures, respectively. For CO, the spectrum can be ascribed to monomeric species in single- and double-substitution sites, to a dimeric species (CO)(2), and to a CO-H(2)O complex. The simulations show that a nearest-neighbor molecular complex CO-H(2) is not responsible for any of the observed spectral fingerprints. The cause of the exit of the molecular hydrogen from the initial cage can be traced to high translational energy of the fragment after the photodissociation. After the matrix has reached a thermal equilibrium, a diffusion driven formation of the complex is possibly hindered by the high rotational zero-point energy developed upon complexation.

Nonresonant inelastic x-ray scattering from actinides and rare earths

Calculated multiplet spectra are presented for the electric-multipole transitions in nonresonant inelastic x-ray scattering (NIXS) at the ${O}_{4,5}$ edges of actinides and the ${N}_{4,5}$ edges of rare earths. The multiplet structure is characteristic for the $f$ count as well as for the angular momentum coupling. As a remarkable peculiarity, the calculations for the actinide ${O}_{4,5}$ edge show that the higher multipole spectra resemble $jj$ coupling, whereas the dipole spectrum is close to $LS$ coupling. The exchange integral ${G}^{1}(5d,5f)$ is responsible for a shift of $\ensuremath{\sim}$15 eV of the dipole spectrum to higher energy. This high energy is conserved by a sum rule for the average energy of the accessible final states. In the higher multipole spectra, where the allowed final states are different, the splitting by the $5d$ spin-orbit interaction exceeds that of the electrostatic interaction. This leads to a distinct spin-orbit-split doublet structure, with a broad first peak and a narrower second peak. According to the spin-orbit sum rule, the $5f$ spin-orbit interaction per hole is linearly related to the core-level branching ratio, where the proportionality factor is opposite in sign for the $k=3$ and 5 spectra. Compared to the $k=3$ spectrum, the $k=5$ spectrum has overall a lower intensity in the low-energy region but a higher intensity in the high-energy region, especially for the heavier elements in the series. The NIXS at the rare-earth ${N}_{4,5}$ edge is quite different since the electrostatic and core spin-orbit splitting in the $k=3$ and 5 spectra are of similar size. The pre-edge region of the rare-earth spectra, where the linewidth is narrow, shows a rich multiplet structure that depends strongly on the initial-state $J$ value.

Maximum carbonyl‐coordination number of scandium Computational study of Sc(CO)n (n = 1–7), Sc(CO)7− and Sc(CO)63−

AbstractUnderstanding the maximum bonding ability is very important with the potential both to design new compounds and to broaden chemists' imagination. While the coordination ability of the late transition metals has been richly understood, that of scandium is very poor. In this work, a detailed computational study on the equilibrium geometries, stability and vibrational frequencies of a series of Sc(CO)n (n = 1–7), Sc(CO) and Sc(CO) is reported using density functional theory functionals and the coupled cluster (single‐point) method with 6‐311+G(3df) basis set. It was shown that the obtained sequential and average CO binding energies of Sc(CO)n (n = 4–7), Sc(CO) and Sc(CO) are comparable to those of the experimentally known species, i.e., smaller Sc‐carbonyls (n ≤3) and the analog Ti(CO)7+. Thus, the studied high scandium carbonyls could all be experimentally accessible. In addition, the studied Sc(CO)n generally favor the low‐spin ground state (doublet) structures except ScCO and Sc(CO)3 that are in the quartet states. The previously uncertain spectrum bands were assigned to Sc(CO)4 and Sc(CO)5 in this work. In all, the appreciable stability suggested that the last 18‐electron first‐row transition metal carbonyls, that is, Sc(CO) and Sc(CO), could be accessible in experiment. © 2013 Wiley Periodicals, Inc.

The relationship between hydrogen and paramagnetic defects in thin film silicon irradiated with 2 MeV electrons

After irradiation of hydrogenated amorphous and microcrystalline silicon (a-Si:H and μc-Si:H) with 2 MeV electrons at 100 K, we observe satellite-like components close to the dominating electron spin resonance (ESR) signal of these materials. The satellites overlap with the commonly observed dangling bond resonance and are proposed to originate from a hyperfine interaction with the nuclear magnetic moment of hydrogen atoms in a-Si:H and μc-Si:H. Our present study is focused on the verification of this hypothesis. Equivalent hydrogenated and deuterated a-/μc-Si:H/D materials have been investigated with ESR before and after 2 MeV electron bombardment. From the difference between ESR spectra of hydrogenated and deuterated samples we identify the doublet structure in the ESR spectra as a hyperfine pattern of hydrogen-related paramagnetic centers. The observations of H-related paramagnetic centers in a-/μc-Si:H are of particular interest in view of metastability models of a-Si:H, which include H-related complexes as precursors for the stabilization of the metastable Si dangling bonds. The nature of the observed center is discussed in the light of known H-related complexes in crystalline Si and suggested H-related dangling bonds in a-Si:H.

Na I spectra in the 1.4–14 micron range: transitions and oscillator strengths involving f-, g-, and h-states

Context. Compared with the visible and ultraviolet ranges, fewer atomic and ionic lines are available in the infrared spectral region. Atlases of stellar spectra often provide only a short list of identified lines, and modern laboratory-based spectral features for wavelengths longer than 1 micron are not available for most elements. For the efficient use of the growing capabilities of infrared (IR) astronomy, detailed spectroscopical information on atomic line features in the IR region is needed. Aims. Parts of the infrared stellar (e.g., solar) spectra in the 1200–1800 cm-1 (5.6–8 μ m) range have never been observed from the ground because of heavy contamination of the spectrum by telluric absorption lines. Such an infrared spectrum represents a great challenge for laboratory observations of new, unknown infrared atomic transitions involving the atomic levels with high orbital momentum and their comparison with the available spectra. Methods. The vapors of excited Na i atoms are produced during the ablation of the salt (sodium iodide, Na i) targets by a high-repetition rate (1.0 kHz) pulsed nanosecond ArF laser ExciStar S-Industrial V2.0 1000, pulse length 12 ns, λ = 193 nm, output energy of 15 mJ, fluence about 2–20 J/cm2 inside a vacuum chamber (average pressure 10-2 Torr). The time-resolved emission spectrum of the neutral atomic potassium (Na i) was recorded in the 700–7000 cm-1 region using the Fourier transform infrared spectroscopy technique with a resolution of 0.02 cm-1 . The f -values calculated in the quantum-defect theory approximation are presented for the transitions involving the reported Na i levels. Results. This study reports precision laboratory measurements for 26 Na i lines in the range of 700–7000 cm-1 (14–1.4 μ m), including 20 lines not measured previously in the laboratory. This results in newly observed 7h, 6h, and 6g levels, and improved energy determination for ten previously known levels. The doublet structure of the 4f level has been observed for the first time. For transitions between the observed levels, we report calculated f -values that agree reasonably well with experiment.Conclusions. The recorded Na i line features agree with the data from the available solar spectrum atlases. The energy values of Na i 4s, 4p, 5p, 6p, 4f, 5f, and 5g levels extracted from our spectra have lower uncertainties as compared to the values reported several decades ago, but the latter values slightly differ from ours.

Three-level medium as a former of a series of short light pulses

We study propagation of optical radiation in a gaseous medium consisting of atoms with doublet structure of the ground state. It is shown that at small deviation of the amplitude of the wave incident at the medium from the regime of adiabatically slow variation the medium polarization becomes periodically modulated. In this case the transmitted wave acquires amplitude modulation in addition to phase modulation. Under favorable conditions this modulation transforms the input quasimonochromatic wave into a regular sequence of short pulses. We show that it is possible to generalize this scheme for more complex structure such as molecules and semiconductor constructions.

Giant Rabi splitting in a metallic cluster–cavity system

We theoretically investigate the photoabsorption cross-section of a cluster of alkali atoms embedded in a single-mode quantum microcavity. We show that if the energy of the giant plasmonic resonance lies close to the energy of the cavity mode, the strong coupling between the plasmon and cavity photon can occur which is characterized by mode anticrossing and observation of the doublet structure in the photoabsorption spectrum. The characteristic values of the Rabi splitting are expected to be several orders of magnitude larger than those observed in single quantum dot–cavity systems.

Theory of ac Stark splitting in core-resonant Auger decay in strong x-ray fields

In this work we report the modification of the normal Auger line shape under the action of an intense x-ray radiation. Under strong Rabi-type coupling of the core, the Auger line profile develops into a doublet structure with an energy separation mainly determined by the relative strength of the Rabi coupling. In addition, we find that the charge resolved ion yields can be controlled by judicious choice of the x-ray frequency.

Photo-luminescence properties of Cu and Ag doped Li2B4O7 single crystals at low temperatures

UV excited photo luminescence from Li2B4O7:Cu and Li2B4O7:Cu, Ag single crystals has been investigated in the temperature range from 77K to 300K. An excitation band having a doublet structure at 240nm and 262nm was observed for the emission at 370nm that corresponds to 1A1g→1Eg and 1A1g→1T2g crystal field components of the 3d10→3d94s1 transition of Cu+. The relative intensity of these components and their temperature dependence provide a measure of the off-center displacement of the Cu+ ground state in the crystal lattice site. The co-doped Ag plays a role of a sensitizer when doped with Cu and increases the overall emission as the emission between Ag states lies in the excitation region of Cu states. The 370nm emission in both the crystals slightly decreases with temperature; however a sudden increase in the intensity around 264K was observed.

Fingerprints of the Anisotropic Spin-Split Hole Dispersion in Resonant Inelastic Light Scattering in Two-Dimensional Hole Systems

In resonant inelastic light scattering experiments on two-dimensional hole systems in GaAs-Al(x)Ga(1-x)As single quantum wells we find evidence for the strongly anisotropic spin-split hole dispersion at finite in-plane momenta. In all our samples we detect a low-energy spin-density excitation of a few meV, stemming from excitation of holes of the spin-split ground state. The detailed spectral shape of the excitation depends sensitively on the orientations of the linear light polarizations with respect to the in-plane crystal axes. In particular, we observe a doublet structure, which is most pronounced if the polarization of the incident light is parallel to the [110] in-plane direction. Theoretical calculations of the Raman spectra based on a multiband k · p approach confirm that the observed doublet structure is due to the anisotropic spin-split hole dispersion.

Analogues of the Lavallo–Grubbs Compound Fe3(C8H8)3: Equilateral, Isosceles, and Scalene Metal Triangles in Trinuclear Cyclooctatetraene Complexes M3(C8H8)3 of the First Row Transition Metals (M = Ti, V, Cr, Mn, Fe, Co, and Ni)

The trinuclear derivative Fe(3)(C(8)H(8))(3) was synthesized in 2009 by Lavallo and Grubbs via the reaction of Fe(C(8)H(8))(2) with a bulky heterocyclic carbene. This fascinating structure is the first example of a derivative of the well-known Fe(3)(CO)(12) in which all 12 carbonyl groups have been replaced by hydrocarbon ligands. The density functional theory predicts a structure having a central Fe(3) equilateral triangle with ∼2.9 Å Fe-Fe single bonded edges bridged by η(5),η(3)-C(8)H(8) ligands. This structure is close to the experimental structure, determined by X-ray crystallography. The related hypoelectronic M(3)(C(8)H(8))(3) derivatives (M = Cr, V, Ti) are predicted to have central scalene M(3) triangles with edge lengths and Wiberg bond indices (WBIs) corresponding to one formal single M-M bond, one formal double M═M bond, and one formal triple M≡M bond. For Mn(3)(C(8)H(8))(3), both a doublet structure with one Mn═Mn double bond and two Mn-Mn single bonds in the Mn(3) triangle, and a quartet structure with two Mn═Mn double bonds and one Mn-Mn single bond are predicted. The hyperelectronic derivatives M(3)(C(8)H(8))(3) have weaker direct M-M interactions in their M(3) triangles, as indicated by both the M-M distances and the WBIs. Thus, Ni(3)(C(8)H(8))(3) has bis(trihapto) η(3),η(3)-C(8)H(8) ligands bridging the edges of a central approximately equilateral Ni(3) triangle with long Ni···Ni distances of ∼3.7 Å. The WBIs indicate very little direct Ni-Ni bonding in this Ni(3) triangle and thus a local nickel environment in the singlet Ni(3)(C(8)H(8))(3) similar to that observed for diallylnickel (η(3)-C(3)H(5))(2)Ni.

Core-level positive-ion and negative-ion fragmentation of gaseous and condensed HCCl3 using synchrotron radiation

We investigated the dissociation dynamics of positive-ion and negative-ion fragments of gaseous and condensed HCCl(3) following photoexcitation of Cl 2p electrons to various resonances. Based on ab initio calculations at levels HF/cc-pVTZ and QCISD/6-311G∗, the first doublet structures in Cl L-edge x-ray absorption spectrum of HCCl(3) are assigned to transitions from the Cl (2P(3/2),(1/2)) initial states to the 10a(1)(∗) orbitals. The Cl 2p → 10a(1)(∗) excitation of HCCl(3) induces a significant enhancement of the Cl(+) desorption yield in the condensed phase and a small increase in the HCCl(+) yield in the gaseous phase. Based on the resonant photoemission of condensed HCCl(3), excitations of Cl 2p electrons to valence orbitals decay predominantly via spectator Auger transitions. The kinetic energy distributions of Cl(+) ion via the Cl 2p → 10a(1)(∗) excitation are shifted to higher energy ∼0.2 eV and ∼0.1 eV relative to those via the Cl 2p → 10e(∗) excitation and Cl 2p → shape resonance excitation, respectively. The enhancement of the yields of ionic fragments at specific core-excited resonance states is assisted by a strongly repulsive surface that is directly related to the spectator electrons localized in the antibonding orbitals. The Cl(-) anion is significantly reinforced in the vicinity of Cl 2p ionization threshold of gaseous HCCl(3), mediated by photoelectron recapture through post-collision interaction.

Study of proton resonances in 18Ne via resonant elastic scattering of 17F + p and its astrophysical implication in the stellar reaction of 14O(α, p)17F

The stellar 14O (α, p) 17F reaction is thought to be one of the most important breakout reactions from the Hot CNO cycles into the rp-process in Type I X-ray bursters. In the present work, the properties of proton resonances in 18Ne have been investigated efficiently by utilizing a technique of proton resonant elastic scattering with a 17F radioactive-ion (RI) beam and a thick proton target. A 4.22 MeV/nucleon 17F RI beam, which was produced via a projectile-fragmentation reaction and experiencing a series of energy degradation, was separated by a Radioactive Ion Beam Line in Lanzhou (RIBLL) and bombarded a (CH2)n target. Energy spectra of the recoiled protons were measured by two sets of ΔE-E silicon telescope at center-of-mass scattering angles of θ c.m. ≈ 175° ± 5°, θ c.m. ≈ 152° ± 8°, respectively. Several proton resonances in 18Ne were observed, and their resonant parameters have been determined by an R-matrix analysis of the differential cross-sections. A doublet structure around 7.10 MeV has been identified and thought to be one state at 7.05 MeV (2+) and another one at 7.12 MeV (4+). The presently calculated total reaction rates of 14O (α, p) 17F are, at least, a factor of 1.2 ∼ 1.9 larger than the previous ones in a temperature region of 1.7 ∼ 3.0 GK mainly owing to the contribution from the 7.05 MeV (2+) state. This result implies that this breakout reaction may play a more important role than previously expected.