3P1 State Research Articles

Electronic spectroscopy of ytterbium in a neon matrix

The low-lying electronic states of Yb isolated in a solid Ne matrix are characterized through absorption and emission spectroscopy. The absorption spectra of matrix isolated Yb while pumped into its triplet states have been recorded for the first time and the 6s6p (3)P(J) → 5d6s (3)D(1, 2) transition frequencies obtained. Under matrix conditions, the structure of these states is found to be qualitatively the same as in the free atom, but the intersystem crossing rate is observed to be several orders of magnitude greater. A proposed explanation for this is curve crossings between the bound potential energy surface correlated to the 6s6p (1)P(1) state and the potential energy surfaces correlated to the 5d6s (3)D(1, 2) states in isolation. The potentials of the Yb·Ne dimer in its lowest electronic states are computed ab initio and used in a pairwise cluster model to explicitly demonstrate these curve crossings.

Spin-dependent collision of ultracold metastable atoms

Spin-polarized metastable atoms of ultracold ytterbium are trapped at high density and their inelastic collisional properties are measured. We reveal that in collisions of Yb(3P2) with Yb(1S0) there is relatively weak inelastic loss, but with a significant spin-dependence consistent with Zeeman sublevel changes as being the dominant decay process. This is in strong contrast to our observations of Yb(3P2)-Yb(3P2) collisional loss, which are, at low field, much more rapid and have essentially no spin dependence. Our results give a guideline to use the 3P2 states in many possible applications.

Geometric phases generated by the non-trivial spatial topology of static vector fields linearly coupled to a neutral spin-endowed particle: application to 171Yb atoms trapped in a 2D optical lattice

We have constructed the geometric phases emerging from the non-trivial topology of a space-dependent magnetic field B(r), interacting with the spin magnetic moment of a neutral particle. Our basic tool, adapted from a previous work on Berry’s phases, is the space-dependent unitary transformation , which leads to the identity, , at each point r. In the ‘rotated’ Hamiltonian , is replaced by the non-Abelian covariant derivative where can be written as A1(r)Sx + A2(r)Sy + A3(r)Sz. The Abelian differentials Ak(r)·dr are given in terms of the Euler angles defining the orientation of B(r). The non-Abelian field transforms as a Yang–Mills field; however, its vanishing ‘curvature’ reveals its purely geometric character. We have defined a perturbation scheme based upon the assumption that in the longitudinal field A3(r) dominates the transverse field A1, 2(r) contributions, evaluated to second order. The geometry embedded in both the vector field A3(r) and the geometric magnetic field is described by their associated Aharonov–Bohm phase. As an illustration we study the physics of cold 171Yb atoms dressed by overlaying two circularly polarized stationary waves with orthogonal directions, which form a 2D square optical lattice. The frequency is tuned midway between the two hyperfine levels of the (6s6p)3P1 states to protect the optical B(r) field generated by the lattice from the dressed atom instability. The geometric field B3(r) is computed analytically in terms of the Euler angles. The magnitude of the second-order corrections due to the transverse fields can be reduced to the per cent level by a choice of light intensity that keeps the dressed atom loss rate ⩽5 s−1. A second optical lattice can be designed to confine the atoms inside 2D domains where . We extend our analysis to the case of a triangular lattice.

Magnetic states at short distances

The magnetic interactions between a fermion and an antifermion of opposite electric or color charges in the 1S0 and 3P0 states are very attractive and singular near the origin and may allow the formation of new bound and resonance states at short distances. In the two body Dirac equations formulated in constraint dynamics, the short-distance attraction for these states for point particles leads to a quasipotential that behaves near the origin as -\alpha^2/r^2. Both 1S0 and 3P0 states admit two types of eigenstates with drastically different behaviors for the radial wave function u=r\psi. One type of states, with u growing as r^{1+\sqrt(1-4*\alpha^2)/2} at small r, will be called usual states. The other type of states with u growing as r^{(1-\sqrt(1-4*\alpha^2))/2} will be called peculiar states. Both of the usual and peculiar eigenstates have admissible behaviors at short distances. The usual bound 1S0 states possess attributes the same as those one usually encounters in QED and QCD. In contrast, the peculiar bound 1S0 states, yet to be observed, have distinctly different bound state properties and scattering phase shifts. For the 3P0 states, the usual solutions lead to the standard bound state energies and no resonance, but resonances have been found for the peculiar states whose energies depend on the description of the internal structure of the charges, the mass of the constituent, and the coupling constant. The existence of both usual and peculiar eigenstates in the same system leads to the non-self-adjoint property of the mass operator and two non-orthogonal complete sets. The mass operator can be made self-adjoint with a single complete set of admissible states by introducing a new peculiarity quantum number and an enlarged Hilbert space.

S-Factor of radiative р 13C capture

The possibility of description of experimental data on the astrophysical S-factor of radiative р 13C capture within the framework of the potential cluster model with forbidden states is analyzed at energies in the range 0.03–0.8 MeV. It is demonstrated that the behavior of the astrophysical S-factor can be explained based on the Е1-transition to the bound 3 P 1 state of the 14N nucleus in the р 13С channel from the 3 S 1 wave of р 13С scattering at resonant energy of 0.55 MeV (l.s.).

Spectroscopy and dynamics of barium-doped helium nanodroplets

Excitation spectra up to the ionization threshold are reported for barium atoms located on the surface of helium nanodroplets. For states with low principal quantum number, the resonances are substantially broadened and shifted towards higher energy with respect to the gas phase. This has been attributed to the repulsive interaction of the excited atom with the helium at the Franck-Condon region. In contrast, for states with high principal quantum number the resonances are narrower and shifted towards lower energies. Photoelectron and ZEKE spectroscopy reveal that the redshift results from a lowering of the ionization threshold due to polarization of the helium by the barium ionic core. As a result of the repulsive interaction with the helium, excited barium atoms desorb from the surface of the droplets. Only when excited to the 6s6p (1)P(1) state, which reveals an attractive interaction with the helium, the atoms remain attached to the droplets.

Enhanced photoluminescence intensity of Y2O3: Eu3+ Sheets by codoping Pr3+ and involved energy transfer mechanisms

Y2O3: Eu3+ has been widely applied as red phosphors in the fields of displaying and illumination. Here, we report the enhanced luminescence intensity of Y2O3: Eu3+ by codoping Pr3+ ion. The Pr3+ and Eu3+ doped Y2O3 microsheets with high aspect ratio were synthesized by a simple route combining chemical precipitation and pyrolysis, which could emit intense red light centered at 610nm under the 254 and 365nm UV excitation. The fluorescence measurement indicated that the luminescence intensity of Y2O3: Eu3+, Pr3+ did not increase monotonously with increasing Pr3+ concentration. The highest improvement of the photoluminescence intensity of Y2O3:Eu3+ was realized in the sample doped with 2mol% Pr3+, which was of 17.8% higher than the whole intensity of only Eu3+ doped Y2O3.The mechanism analysis based on SEM, XRD, fluorescence spectra, and simplified energy level diagram indicated that (1) energy transfer process between Pr3+ and Eu3+, (2) crystallinity, and (3) symmetry should respond for this nonmonotonous variation phenomenon by competition with each other. For energy transfer process between Pr3+ and Eu3+, it was suggested that the cross relaxation of 5D0+7F1(Eu3+)↔3P0+3H6(Pr3+) and the efficient energy transfer from 3P0 state of Pr3+ to 5D1 energy level of Eu3+ lead to the improvement of the population of the 5D0 state of Eu3+ so that the 610 red emission of Eu3+ ion was accordingly enhanced.

Spin correlations of $\varLambda{\bar{\varLambda}}$ pairs as a probe of quark–antiquark pair production

The polarizations of Λ and ${\bar{\varLambda}}$ are thought to retain memories of the spins of their parent s quarks and ${\bar{s}}$ antiquarks, and are readily measurable via the angular distributions of their daughter protons and antiprotons. Correlations between the spins of Λ and ${\bar{\varLambda}}$ produced at low relative momenta may therefore be used to probe the spin states of $s {\bar{s}}$ pairs produced during hadronization. We consider the possibilities that they are produced in a 3P0 state, as might result from fluctuations in the magnitude of $\langle {\bar{s}} s \rangle$ , a 1S0 state, as might result from chiral fluctuations, or a 3S1 or other spin state, as might result from production by a quark–antiquark or gluon pair. We provide templates for the $p {\bar{p}}$ angular correlations that would be expected in each of these cases, and discuss how they might be used to distinguish $s {\bar{s}}$ production mechanisms in pp and heavy-ion collisions.

Storage-ring measurement of the hyperfine-induced2s2p3P0→2s21S0transition rate in berylliumlike sulfur

The hyperfine induced 2s 2p 3P0 -> 2s2 1S0 transition rate in Be-like sulfur was measured by monitoring the decay of isotopically pure beams of 32-S12+ and 33-S12+ ions in a heavy-ion storage ring. Within the 4% experimental uncertainty the experimental value of 0.096(4)/s agrees with the most recent theoretical results of Cheng et al. [Phys. Rev. A 77, 052504 (2008)] and Andersson et al. [Phys. Rev. A 79, 032501 (2009)]. Repeated experiments with different magnetic fields in the storage-ring bending magnets demonstrate that artificial quenching of the 2s 2p 3P0 state by these magnetic fields is negligible.

Populations of metastable and resonant argon atoms in radio frequency magnetron plasmas used for deposition of indium-zinc-oxide films

This work reports optical absorption spectroscopy measurements of the number density of Ar atoms in resonant (3P1, 1P1) and metastable (3P2, 3P0) states in rf magnetron sputtering plasmas used for the deposition of ZnO-based thin films. While the density of Ar 3P2 and 3P0 was fairly independent of pressure in the range of experimental conditions investigated, the density of Ar 3P1 and 1P1 first sharply increased with pressure and then reached a plateau at values close to those of the 3P2 and 3P0 levels at pressures above about 50 mTorr. At such pressures, ultraviolet radiation from resonant states becomes trapped such that these levels behave as metastable states. For a self-bias voltage of −115 V and pressures in the 5–100 mTorr range, similar number densities of Ar resonant and metastable atoms were obtained for Zn, ZnO, and In2O3 targets, suggesting that, over the range of experimental conditions investigated, collisions between these excited species and sputtered Zn, In, and O atoms played only a minor role on the discharge kinetics. The metastable-to-ground state number density ratios were also fitted to the predictions of a global model using the average electron temperature, Te, as the only adjustable parameter. For all targets examined, the values of Te deduced from this method were in excellent agreement with those obtained from Langmuir probe measurements.

A theoretical study on electron impact excitation differential cross sections and Stokes parameters of Mg atom

Differential cross sections (DCSs) and Stokes parameters for electron impact excitation of 3s3p 1P1, 3s4p 1P1 states in magnesium are calculated by using the fully relativistic distorted-wave (RDW) program REIE06. In the calculations, the relativistic effects and electron correlations are considered systematically. The results are analyzed and compared with available experimental data and theoretical calculations, and they are in good agreement with each other.

Experimental investigation of spectrum of strontium intercombination transition

We observe the fluorescence and the saturated fluorescence spectra of (5s2)1S0(5s5p)3P1 intercombination transition of thermal strontium atomic beam. Experimental investigation of 88Sr(5s2)1S0(5s5p)3P1 intercombination transition is performed on the different experimental conditions. Our study indicates that experimental parameters affect spectra largely, including temperature, intensity of laser and scanning frequency of laser. Intensity of spectrum is reciprocal of scanning frequency of laser due to long lifetime of (5s5p)3P1 state of Sr atom. Owing to Doppler broadening, transit broadening and other experimental factors, the linewidth of (5s2)1S0(5s5p)3P1 fluorescence spectrum is far more than its natural linewidth and proportional scanning frequency of laser.

Radiative lifetime of the v′1(3 P 2) states of the HgAr, HgKr, and HgXe molecules and the probabilities A(v′, v″) of the v′1(3 P 2−v″0+(1 S 0) transitions

A semiempirical method of analysis of quasi-molecular terms in conjunction with experimental potentials of interaction of Hg(6(3P1)) atoms with Ar, Kr, and Xe atoms are used to obtain the Hg(63P2)-Ar, Kr, Xe interaction potential, which are applied to calculating the radiative lifetimes of the v′1(3P2) states of the HgAr, HgKr, and HgXe molecules and the probabilities of the v′1(3P2)−v″0+(1S0) transitions.

Study on Energy Transfer and Energy Migration of Ca2Gd8(SiO4)6O2:Dy3+ Phosphor Films

Being a kind of rare-earth-metal silicate with oxidapatite structure, Ca2R8(SiO4)6O2 (R = Y, Gd, La) is a promising material doped with rare earth, and widely used as phosphors. In this thesis, Ca2Gd8(SiO4)6O2:Dy3+ films were prepared by the sol-gel method. X-ray diffraction (XRD), atomic force microscopy (AFM), photoluminescence (PL) spectra, and lifetimes were used to characterize the resulting films. AFM study indicated that the phosphor films consisted of 120 nm homogeneous particles. By combining the model of Burshtein for donor-donor migration and the V-F-B model for donor-acceptor energy transfer, the experimental luminescence decay curve of 6P(J) state of Gd3+ was re-simulated. It is found that concentration quenching of Gd3+ can be due to the result of the joint action of donor-donor (Gd3+-Gd3+) energy migration and donor-acceptor (Gd3+-Dy3+) energy transfer.

The effects of quantum interference between direct and resonant photorecombination of H-like Ar17+ ions

The multiconfiguration Dirac–Fock method has been used to study interference effects between direct and resonant photorecombination (i.e. radiative and dielectronic recombination) from the ground state 1s2S1/2 of H-like Ar17+ ions via doubly excited 2s21S0, 2s2p 3P0, 1, 2, 1P1 and 2p23P0, 1, 2, 1D2, 1S0 resonances of He-like Ar16+ ions combined with the Fano parameterization technique. In order to produce total photorecombination spectra, it is necessary to calculate the energy levels of the 1s of H-like Ar17+ ions, 1s2, 1s2l and 2l2l′ (l,l′ =0, 1) of He-like Ar16+ ions, the radiative and nonradiative properties of the doubly excited states of He-like Ar16+ ions, and the direct and resonant photorecombination cross sections from the 1s state of H-like Ar17+ ions into the ground state 1s2 and the single excited states of 1s2l (l=0, 1) of He-like Ar16+ ions, in detail. Based on good agreement between the present calculations and other available experimental and theoretical results, the interference profile determined by the so-called Fano parameters q and ρ2 is also shown. The results indicate that interference effects are remarkable at some resonances, especially near the doubly excited 2s2p 1P1 state of He-like Ar16+ ions, and strongly influence the intensity of the wing of the nonresonant background in the photorecombination of H-like Ar17+ ions through comparison between the final Fano and total radiative recombination to dielectronic recombination spectra.

Excitation of Rydberg states in rubidium with near infrared diode lasers

A system of three external cavity diode lasers is used to excite Rydberg states in rubidium. The 5S→5P→5D transitions are driven using lasers with λ = 780 and 776 nm respectively. From the 5D state, atoms fluoresce down to the 6P state. The final transition to Rydberg levels is from the 6P state with laser light near λ = 1016 nm. The nS and nD Rydberg states are accessible directly and with the application of a modest electric field nP states can also be excited. As a test of this system, Stark spectra are collected for nD and nP states.

Highly Stable Red Oxynitride β-SiAlON:Pr3+ Phosphor for Light-Emitting Diodes

Trivalent Pr3+-doped oxynitirde red phosphors β-SiAlON with composition Si6–zAlzOzN8–z:Prx (z = 0–2.0, x = 0.016) were synthesized by gas pressure sintering (GPS) at 1950 °C for 2 h. Red luminescence in the range 600–650 nm was detected upon excitation with 460 nm blue light, indicating that the phosphor can be excited by blue InGaN light-emitting diodes (LED). The crystallization and cell parameters of samples were investigated by powder X-ray diffraction (XRD), Rietveld refinement, and high-resolution transmission electron microscopy (HRTEM). Energy-dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM) were further adopted to examine the effect of Al substitution on the microstructure. 27Al and 29Si solid-state nuclear magnetic resonance (NMR) data are consistent with SiN4–xOx and partially substituted AlN4–xOx tetrahedra. The temperature-dependent luminescence from the 1D2 and 3P0 states of Pr3+ were studied (10–573 K), and the integrated red emission from 600 to 650 nm increased w...

Magneto-optical trapping of bosonic and fermionic neon isotopes and their mixtures: isotope shift of the 3P2 ↔ 3D3 transition and hyperfine constants of the 3D3 state of 21Ne

We have magneto-optically trapped all three stable neon isotopes, including the rare 21Ne, and all two-isotope combinations. The atoms are prepared in the metastable 3P2 state and manipulated via laser interaction on the 3P2 ↔ 3D3 transition at 640.2 nm. These cold (T ≈ 1 mK) and environmentally decoupled atom samples present ideal objects for precision measurements and the investigation of interactions between cold and ultracold metastable atoms. In this work, we present accurate measurements of the isotope shift of the 3P2 ↔ 3D3 transition and the hyperfine interaction constants of the 3D3 state of 21Ne. The determined isotope shifts are (1625.9 ± 0.15) MHz for 20Ne ↔ 22Ne, (855.7 ± 1.0) MHz for 20Ne ↔ 21Ne, and (770.3 ± 1.0) MHz for 21Ne ↔ 22Ne. The obtained magnetic dipole and electric quadrupole hyperfine interaction constants are A(3D3) = (−142.4 ± 0.2) MHz and B(3D3) = (−107.7 ± 1.1) MHz, respectively. All measurements give a reduction of uncertainty by about one order of magnitude over previous measurements.

Laser spectroscopy of the (1s22s2p) 3P0–3P1 level splitting in Be-like krypton

Heavy few-electron ions, such as He-, Li- and Be-like ions, are ideal atomic systems to study the effects of correlation, relativity and quantum electrodynamics. Very recently, theoretical and experimental studies of these species achieved a considerable improvement in accuracy. Be-like ions are interesting because their first excited state, i.e. (1s22s2p)3P0, has an almost infinite lifetime (τ0) in the absence of nuclear spin (I), as it can only decay by a two-photon E1M1 transition to the (1s22s2)1S0 ground state. In addition, the energy difference between the 3P0 and the next higher-lying 3P1 state is expected to remain almost completely unaffected by QED effects, and should thus be dominated by the effects of correlation and relativity. Therefore, we want to determine the (1s22s2p) 3P0–3P1 level splitting in Be-like krypton (84Kr32+), which has I=0, by means of laser spectroscopy at the experimental storage ring at GSI. In such an experiment, the energy splitting can be obtained with very good accuracy and can be compared with recent calculations.

Loading rate of Yb+ loaded through photoionization in radiofrequency ion trap

We investigate the loading rate of Yb+ ions loaded through photoionization in a radiofrequency trap. The absolute or relative number of the loaded trapped ions is measured by use of an electric resonance of the secular motion. This method is applicable even in the presence of anharmonicity. In two-color photoionization, where the first-excitation laser drives the 1S0–1P1 transition in the Yb atom and the second one ionizes the atom from the 1P1 state, the loading rate is at its highest by the excitation of the ionization potential. A similar loading rate is observed at the second-laser wavelength around 369.5 nm, which is the wavelength for the cooling transition of Yb+. We estimate the loading cross section to be 40(15) Mb for the two-color excitation of the ionization potential. The excitation of the Yb atoms in the Rydberg states is detected by the enhancement of the loading rate. By irradiation with only the first-excitation laser, Yb+ is produced at a rate three orders of magnitude smaller than that when the non-resonant two-photon absorption from the 1P1 state is the dominant process. We also measure the charge-exchange rate between Yb+ and Yb, and discuss its effect on isotope-selective photoionization loading.