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Articles 31891 - 31920 of 36559
Full-Text Articles in Physical Sciences and Mathematics
Observation Of Beam-Induced Changes In The Polarization Of Balmer-Α Radiation Emitted Following Beam--Tilted-Foil Transmission, Wang Qi, David D. Allred, Larry V. Knight, Douglas L. Harper, Royal G. Albridge, Norman H. Tolk
Observation Of Beam-Induced Changes In The Polarization Of Balmer-Α Radiation Emitted Following Beam--Tilted-Foil Transmission, Wang Qi, David D. Allred, Larry V. Knight, Douglas L. Harper, Royal G. Albridge, Norman H. Tolk
Faculty Publications
Measurements of the circular polarization of Balmer-α radiation emitted by excited hydrogen atoms, following the transmission of (20-50)-keV protons through thin, tilted amorphous carbon foils, exhibit markedly unexpected behavior as a function of exposure of the foil to the proton beam. Specifically, the circular polarization changes from an initially well understood tilt-angle dependence to a behavior which, for low tilt angles, gives the opposite handedness of circular polarization from that predicted. In addition, the degree of alignment, indicated by the linear Stokes parameter M/I, is enhanced also as a function of dose. These changes in the tilt-angle dependence of the …
Pion Fusion In Peripheral Pp Collisions, Alec Schramm, Burndt Muller
Pion Fusion In Peripheral Pp Collisions, Alec Schramm, Burndt Muller
Alec J Schramm
We estimate the cross section for quasielastic double pion exchange in high energy proton-proton collisions. Total and elastic ππ cross sections are calculated in an equivalent pion approximation, with pion-baryon vertices taken from chiral perturbation theory.
Forming B1-XCX Semiconductor Devices By Chemical Vapor Deposition, Peter A. Dowben
Forming B1-XCX Semiconductor Devices By Chemical Vapor Deposition, Peter A. Dowben
Peter Dowben Publications
Active semiconductor devices including heterojunction diodes and thin film transistors are formed by PECVD deposition of a boron carbide thin film on an N-type substrate. The boron to carbon ratio of the deposited material is controlled so that the film has a suitable band gap energy. Boron carbides such as B4.7C, B7.2C and B19C have suitable band gap energies between 0.8 and 1.7 eV. The stoichiometry of the film can be selected by varying the partial pressure of precursor gases, such as nido pentaborane and methane. The precursor gas or gases are energized, e.g., …
Simple Description Of Pion-Pion Scattering To 1 Gev, Joseph Schechter, Masayasu Harada, Francesco Sannino
Simple Description Of Pion-Pion Scattering To 1 Gev, Joseph Schechter, Masayasu Harada, Francesco Sannino
Physics - All Scholarship
Motivated by the 1/Nc expansion, we present a simple model of pion-pion scattering as a sum of a `current-algebra' contact term and resonant pole exchanges. The model preserves crossing symmetry as well as unitarity up to 1.2 GeV. Key features include chiral dynamics, vector meson dominance, a broad low energy scalar (sigma) meson and a `Ramsauer-Townsend' mechanism for the understanding of the 980 MeV region. We discuss in detail the `regularization' (corresponding to rescattering effects) necessary to make all these nice features work.
Evidence For Crystal-Field Splitting In Surface-Atom Photoemission From Potassium, G. K. Wertheim, D. Mark Riffe
Evidence For Crystal-Field Splitting In Surface-Atom Photoemission From Potassium, G. K. Wertheim, D. Mark Riffe
All Physics Faculty Publications
Photoemission spectra from the shallow 3p3/2 core levels of the surface atoms of metallic potassium exhibit the effects of a small but measurable crystal-field splitting of ∼38 meV. It manifests itself mainly as an apparent angle-dependent modulation of the spin-orbit splitting. This phenomenon may, in general, interfere with accurate determinations of surface-atom core-level shifts.
Complexity Properties Of The Cellular Automaton Game Of Life, Andreas Rechtsteiner
Complexity Properties Of The Cellular Automaton Game Of Life, Andreas Rechtsteiner
Dissertations and Theses
The Game of Life is probably the most famous cellular automaton. Life shows all the characteristics of Wolfram's complex Class IV cellular automata: long-lived transients, static and propagating local structures, and the ability to support universal computation.
We examine in this thesis questions about the geometry and criticality of Life. We find that Life has two different regimes with different dimensionalities. In the small scale regime Life shows a fractal dimensionality with Ds = 0.658 and in the large scale regime D1 = 2.0, suggesting that the objects of Life are randomly distributed. We find that Life …
The Geometry And Kinematics Of The Broad-Line Region In Ngc 5548 From Hst And Iue Observations, Ignaz Wanders, Mike R. Goad, Kirk T. Korista, Bradley M. Peterson, Keith Horne, Gary J. Ferland, Anuradha P. Koratkar, Richard W. Pogge, Joseph C. Sheilds
The Geometry And Kinematics Of The Broad-Line Region In Ngc 5548 From Hst And Iue Observations, Ignaz Wanders, Mike R. Goad, Kirk T. Korista, Bradley M. Peterson, Keith Horne, Gary J. Ferland, Anuradha P. Koratkar, Richard W. Pogge, Joseph C. Sheilds
Physics and Astronomy Faculty Publications
The spatial and radial velocity distribution of broad-line-emitting gas in the Seyfert 1 galaxy NGC 5548 is examined through the process of reverberation mapping, which is done by detailed comparison of continuum and emission-line variations. Recent spectroscopic monitoring of NGC 5548 with HST and IUE allows us to resolve the "transfer function" (TF) that relates the continuum and emission-line variability. We also examine the radial velocity-resolved TFs, and confirm that predominantly radial motions of the line-emitting clouds can be excluded. We find that a broad-line region comprised of clouds that are orbiting a central source of mass ~108 M …
Tailoring Of The Magnetic Properties Of Smco5:Nb0.33Cr0.67 Nanocomposites Using Mechanical Alloying, Richard L. Schalek, Diandra Leslie-Pelecky, John Knight, David J. Sellmyer, Steven C. Axtell
Tailoring Of The Magnetic Properties Of Smco5:Nb0.33Cr0.67 Nanocomposites Using Mechanical Alloying, Richard L. Schalek, Diandra Leslie-Pelecky, John Knight, David J. Sellmyer, Steven C. Axtell
David Sellmyer Publications
Nanocomposite structures composed of ferromagnetic particles dispersed in a matrix are systems in which the magnetic properties can be tailored by varying the size and spacing of the ferromagnetic particles. Nanocomposites of SmCo5 in a non-magnetic Nb0.33Cr0.67 matrix exhibit a wide variety of magnetic properties. SmCo5 powder is premilled prior to mechanical alloying. The premilliing results in a maximum coercivity of 16 kOe after 2 hours of milling, and an enhanced remanence ratio. Both features may be due to exchange anisotropy and/or exchange coupling between hard and soft ferromagnetic phases. The nanocomposite samples show that, …
Magnetic Switching Volumes Of Cosm Thin Films For High Density Longitudinal Recording, E.W. Singleton, Z.S. Shan, Y.S. Jeong, David J. Sellmyer
Magnetic Switching Volumes Of Cosm Thin Films For High Density Longitudinal Recording, E.W. Singleton, Z.S. Shan, Y.S. Jeong, David J. Sellmyer
David Sellmyer Publications
For a high density recording media, the magnetic switching volume is of great importance when considering media noise and thermal stability. CoSm//Cr films have been prepad and the influence of the Cr underlayer thickness and of the magnetic layer preparation conditions on the magnetic switching volume have been investigated through magnetic viscosity and remnance curve measurements. The measured switching volumes ranged from 3.0 to 15.2x10-18 cm3, and implications regarding noise and thermal stability are discussed.
A Quasiparticle Trap Assisted Transition Edge Sensor For Phonon Mediated Particle Detection, K. D. Irwin, S. W. Nam, Blas Cabrera, B. Chugg, Betty A. Young
A Quasiparticle Trap Assisted Transition Edge Sensor For Phonon Mediated Particle Detection, K. D. Irwin, S. W. Nam, Blas Cabrera, B. Chugg, Betty A. Young
Physics
ABSTRACT We have demonstrated the operation of composite superconducting tungsten and aluminum transition‐edge sensors which take advantage of quasiparticle trapping and electrothermal feedback. We call these devices W/Al QETs (quasiparticle‐trap‐assisted electrothermal feedback transition‐edge sensors). The quasiparticle trapping mechanism makes it possible to instrument large surface areas without increasing sensor heat capacity, thus allowing larger absorbers and reducing phonon collection times. The sensor consists of a 30‐nm‐thick superconducting tungsten thin film with Tc∼80 mK deposited on a high‐purity silicon substrate. The W film is patterned into 200 parallel lines segments, each 2 μm wide and 800 μm long. Eight …
Analysis Of Ladar Range Resolution Enhancement By Sinusoidal Phase Modulation, Leonard T. Masters, Martin B. Mark, Bradley D. Duncan
Analysis Of Ladar Range Resolution Enhancement By Sinusoidal Phase Modulation, Leonard T. Masters, Martin B. Mark, Bradley D. Duncan
Electro-Optics and Photonics Faculty Publications
The ability of a ladar system to resolve two or more separate returns from a combined echo is related to the effective correlation bandwidth of the pulse emitted by the ladar system. Phase modulation of an outgoing pulse introduces additional frequency components, which increases the effective correlation bandwidth of the pulse and thus improves the range resolution of the system. In this paper, we discuss the general theoretical basis for achieving improved range resolution using a modulated waveform and a matched filter receiver. We then demonstrate these concepts by considering the particular case of improved range resolution for a sinusoidally …
Spin Polarization Of The Conduction Bands Of Gd(0001)*, Dongqi Li, J. Pearson, S.D. Bader, D. N. Mcilroy, C. Waldfried, Peter A. Dowben
Spin Polarization Of The Conduction Bands Of Gd(0001)*, Dongqi Li, J. Pearson, S.D. Bader, D. N. Mcilroy, C. Waldfried, Peter A. Dowben
Peter Dowben Publications
Angle- and spin-resolved photoemission was utilized to investigate the 5d bulk bands and the surface state of Gd(0001) in the temperature range of 130 - 350 K. The bulk bands at 1-2 eV below the Fermi energy EF show Stoner-like behavior, while the temperature dependence of the surface state near EF indicates spin-mixing behavior due to fluctuating local 5d moments. The secondary electron spectra of the Gd surfaces both before and after initial oxygen adsorption show a polarization dip at low kinetic energies due to the extra scattering channel for minority electrons via the unoccupied 4ƒ level. The …
Magnetic Properties And Structure Of Fe/Pt Thin Films, C.P. Luo, David J. Sellmyer
Magnetic Properties And Structure Of Fe/Pt Thin Films, C.P. Luo, David J. Sellmyer
David Sellmyer Publications
The structural transfqmation from fcc to fct and relevant magnetic properties of initially multilayered Fe/Pt films were studied. When the as-deposited FePt films were annealed at the temperature of 300°C and up, the fct-phase was formed. Rather square hysteresis loops and large coercivities were measured from the annealed films. The films annealed at 300°C retain a layered structure.
A Magnetic, Neutron-Diffraction, And Mössbauer Spectral Study Of The Ce₂Fe₁₇₋ₓsiₓ Solid Solutions, D. P. Middleton, Sanjay R. Mishra, Gary J. Long, Oran Allan Pringle, Zhongbo Hu, William B. Yelon, Fernande Grandjean, K. H. J. Buschow
A Magnetic, Neutron-Diffraction, And Mössbauer Spectral Study Of The Ce₂Fe₁₇₋ₓsiₓ Solid Solutions, D. P. Middleton, Sanjay R. Mishra, Gary J. Long, Oran Allan Pringle, Zhongbo Hu, William B. Yelon, Fernande Grandjean, K. H. J. Buschow
Chemistry Faculty Research & Creative Works
The magnetic properties of a series of Ce2Fe17-xSix solid solutions with x equal to 0.0, 0.23, 0.4, 0.6, 0.8, 1.02, 1.98, and 3.20 have been studied by magnetic measurements, neutron diffraction, and Mössbauer spectroscopy. An x-ray-diffraction study indicates that the compounds adopt the rhombohedral Th2Zn 17-type structure. The substitution of silicon for iron in Ce 2Fe17 leads to a contraction of the a axis by 0.2%, an expansion of the c axis by 0.2%, and a consequent reduction of the unit-cell volume by about 0.2% per substituted silicon. Magnetization studies …
High Resolution Electron Microscopy And Nano-Probe Study Of Cosm/Cr Films, Yi Liu, David J. Sellmyer, B. W. Robertson, Z.S. Shan, Sy_Hwang Liou
High Resolution Electron Microscopy And Nano-Probe Study Of Cosm/Cr Films, Yi Liu, David J. Sellmyer, B. W. Robertson, Z.S. Shan, Sy_Hwang Liou
Sy-Hwang Liou Publications
The crystal structure of the crystallites in CoSm thin films deposited on Cr underlayer was studied by nanodiffraction and high resolution electron microscopy (HREM). It was found that the crystallites have a closed-packed structure. Some nanodiffraction patterns taken from different crystallites using a two nanometer probe can be indexed by two layer stacking AB (HCP structure), three layer stacking ABC (FCC structure), and four layer stacking ABAC (double hexagonal structure), suggesting that a particular local stacking mode could exist. [112-0] HREM images confirmed that stacking sequence changes within one crystallite. In local regions, random stacking, and unit cells …
Image Restoration Of Dispersion-Degraded Images From A Liquid-Crystal Beam Steerer, Ronald J. Broessel, Vince Dominic, Russell C. Hardie
Image Restoration Of Dispersion-Degraded Images From A Liquid-Crystal Beam Steerer, Ronald J. Broessel, Vince Dominic, Russell C. Hardie
Electrical and Computer Engineering Faculty Publications
Liquid-crystal arrays represents one of the first practical technologies capable of steering light by electronic control only. We use such a device to steer the field of view of a broadband imaging sensor. Unfortunately, dispersion degrades the image quality by smearing out details in the image and by introducing multiple diffraction orders (echoes) at the detector plane. We present a method to compensate for these unwanted effects and thus restore the broadband images obtained with the beam steerer. We use the beam-propagation method to find the wavelength-dependent impulse response, from which we determine the appropriate Wiener filter. When training data …
Steady-State Kinetics Of Br(2P1/2) Yields Co2(101) Electronic-To-Vibrational Energy Transfer Laser System, Stephen J. Karis
Steady-State Kinetics Of Br(2P1/2) Yields Co2(101) Electronic-To-Vibrational Energy Transfer Laser System, Stephen J. Karis
Theses and Dissertations
Steady state photolysis experiments were conducted to gain information relevant to the construction of a continuous wave electronic to vibrational pumped infrared laser. An Ar+ laser =488 µm) was used to produce the electronically excited state Br(2P1/2) (Br*) via photolysis of molecular bromine. Energy was then transferred to the near resonant vibrational state CO2(101) (CO2) via the collisional quenching of Br* by CO2. The dependence of the 2.71 µm Br* and 4.3 µm CO2 emissions on CO2 pressure was measured, as well as …
Magnetic And Magneto-Optical Properties Of MnXCubi ( X =0.75 - 3.5 ) Films†, Jian Chen, K. Wierman, Roger D. Kirby, David J. Sellmyer
Magnetic And Magneto-Optical Properties Of MnXCubi ( X =0.75 - 3.5 ) Films†, Jian Chen, K. Wierman, Roger D. Kirby, David J. Sellmyer
Department of Physics and Astronomy: Faculty Publications
Abstract - Magnetic and magneto-optical properties of MnxCuBi ( x = 0.75 - 3.5) thin films are presented. With increasing Mn concentration x, the perpendicular anisotropy constant (Ku), the remanence squareness (S = Mr/Ms) and the coercivity (Hc ), of the perpendicular hysteresis loop increase. Remanence squareness as high as 0.95 has been obtained. Kerr rotation (Өk) and ellipticity (ηk) spectra from all samples measured from substrate side are similar, with Өk exhibiting a broad peak in the blue wavelength region with maximum Kerr rotation up …
Recurrences Associated With A Classical Orbit In The Node Of A Quantum Wave Function, John A. Shaw, John B. Delos, Michael Courtney, Daniel Kleppner
Recurrences Associated With A Classical Orbit In The Node Of A Quantum Wave Function, John A. Shaw, John B. Delos, Michael Courtney, Daniel Kleppner
Arts & Sciences Articles
Absorption spectra of atoms in magnetic fields reveal recurrences: manifestations of classical orbits (or quantum wave packets) that go out from the atom and later return. A formula from closed-orbit theory asserts that if the orbit lies on a node of the outgoing wave function, then the strength of the recurrence is zero. New quantum calculations, however, show that the recurrence strength is nonzero, though small. We derive a semiclassical formula for the recurrence strength associated with a classical orbit at a node of the quantum wave function. This formula is compared to the quantum mechanical calculation. Compared to …
Liquid Crystal Displays, Peter J. Collings
Liquid Crystal Displays, Peter J. Collings
Physics & Astronomy Faculty Works
No abstract provided.
Heterodyne Ladar System Efficiency Enhancement Using Single-Mode Optical Fiber Mixers, Donald K. Jacob, Martin B. Mark, Bradley D. Duncan
Heterodyne Ladar System Efficiency Enhancement Using Single-Mode Optical Fiber Mixers, Donald K. Jacob, Martin B. Mark, Bradley D. Duncan
Electro-Optics and Photonics Faculty Publications
A theoretical performance analysis of a heterodyne ladar system incorporating a single-mode fiber receiver has been performed. For our purposes, the performance parameters of interest are the coupling and mixing efficiency of the ladar receiver, as they relate to the overall system carrier-to-noise ratio. For a receiver incorporating a single-mode fiber mixer, the received and local-oscillator fields are matched both spatially and temporally at the detector, yielding 100% mixing efficiency. We have therefore focused our efforts on determining an expression for the efficiency with which a diffuse return from a purely speckle target can be coupled into the receiving leg …
Magnetic And Magneto-Optical Properties Of MnXCubi ( X =0.75 - 3.5 ) Films, Jian Chen, K. Wierman, Roger D. Kirby, David J. Sellmyer
Magnetic And Magneto-Optical Properties Of MnXCubi ( X =0.75 - 3.5 ) Films, Jian Chen, K. Wierman, Roger D. Kirby, David J. Sellmyer
Department of Physics and Astronomy: Faculty Publications
Magnetic and magneto-optical properties of MnxCuBi ( x = 0.75 - 3.5) thin films are presented. With increasing Mn concentration x, the perpendicular anisotropy constant (Ku the remanence squareness (S = Mr/Ms) and the coercivity (Hc)the perpendicular hysteresis loop increase. Remanence squareness as high as 0.95 has been obtained. Kerr rotation (θk) and ellipticity (ηk) spectra from all samples measured from substrate side are similar, with θk exhibiting a broad peak in the blue wavelength region with maximum Kerr rotation up to 0.7 degrees.
Aliasing Reduction In Staring Infrared Imagers Utilizing Subpixel Techniques, Joseph C. Gillette, Thomas M. Stadtmiller, Russell C. Hardie
Aliasing Reduction In Staring Infrared Imagers Utilizing Subpixel Techniques, Joseph C. Gillette, Thomas M. Stadtmiller, Russell C. Hardie
Electrical and Computer Engineering Faculty Publications
We introduce and analyze techniques for the reduction of aliased signal energy in a staring infrared imaging system. A standard staring system uses a fixed two-dimensional detector array that corresponds to a fixed spatial sampling frequency determined by the detector pitch or spacing. Aliasing will occur when sampling a scene containing spatial frequencies exceeding half the sampling frequency. This aliasing can significantly degrade the image quality. The aliasing reduction schemes presented here, referred to as microscanning, exploit subpixel shifts between time frames of an image sequence. These multiple images are used to reconstruct a single frame with reduced aliasing. If …
Light-Heavy Symmetry: Geometric Mass Hierarchy For Three Families, Aharon Davidson, Tomer Schwartz, Kameshwar C. Wali
Light-Heavy Symmetry: Geometric Mass Hierarchy For Three Families, Aharon Davidson, Tomer Schwartz, Kameshwar C. Wali
Physics - All Scholarship
The Universal Seesaw pattern coupled with a Light
↔ Heavy symmetry principle leads to the Diophantine equation N =NXi =1ni, where ni ≥ 0 and distinct. Its unique non-trivial solution (3 = 0+1+2) gives rise to the geometric mass hierarchy mW, mWǫ, mWǫ2 for N = 3 fermion families. This is realized in a model where the hybrid (yet Up ↔ Down symmetric) quark mass relations m dmt ≈ m2 c ↔ mumb ≈ m2 s play a crucial role in expressing the CKM mixings in terms of simple mass ratios, notably sin θC ≈ m c m b . …
Peak Effect In Twinned Superconductors, A. I. Larkin, M. Cristina Marchetti, V. M. Vinokur
Peak Effect In Twinned Superconductors, A. I. Larkin, M. Cristina Marchetti, V. M. Vinokur
Physics - All Scholarship
A sharp maximum in the critical current Jc as a function of temperature just below the melting point of the Abrikosov flux lattice has recently been observed in both low and high temperature superconductors. This peak effect is strongest in twinned crystals for fields aligned with the twin planes. We propose that this peak signals the breakdown of the collective pinning regime and the crossover to strong pinning of single vortices on the twin boundaries. This crossover is very sharp and can account for the steep drop of the differential resistivity observed in experiments.
Correlation Between Screening And Electron Effective Mass Across The Nonmetal-Metal Transition In Ultrathin Films, Jiandi Zhang, D.N. Mcilroy, Peter A. Dowben
Correlation Between Screening And Electron Effective Mass Across The Nonmetal-Metal Transition In Ultrathin Films, Jiandi Zhang, D.N. Mcilroy, Peter A. Dowben
Peter Dowben Publications
Angle-resolved photoemission and resonant photoemission have been used to determine the relative changes of the electron effective mass and the screening parameter across the nonmetal to metal transition in the magnesium thin films on Mo(112). Both the screening length and the electron effective mass exhibit a gradual change with Mg coverage in the transition range between half and one monolayer. The relationship of these two different measures of metallicity is in surprisingly good agreement with the relationship predicted by theory for the Mott-Hubbard transition. Our results indicate the importance of electron-electron correlation within the overlayer.
Lattice Quantum Gravity: Review And Recent Developments, Simon Catterall
Lattice Quantum Gravity: Review And Recent Developments, Simon Catterall
Physics - All Scholarship
We review the status of different approaches to lattice quantum gravity indicating the successes and problems of each. Recent developments within the dynamical triangulation formulation are then described. Plenary talk at LATTICE 95 July 11-15, Melbourne, Australia.
A Real-Space Renormalization Group For Random Surfaces, Simon Catterall, G. Thorleifsson
A Real-Space Renormalization Group For Random Surfaces, Simon Catterall, G. Thorleifsson
Physics - All Scholarship
We propose a new real-space renormalization group transformation for dynamical triangulations. It is shown to preserve geometrical exponents such as the string susceptibility and Hausdorff dimension. We furthermore show evidence for a fixed point structure both in pure gravity and gravity coupled to a critical Ising system. In the latter case we are able to extract estimates for the gravitationally dressed exponents which agree to within 2-3% of the KPZ formula.
Electrostatic Interactions At Membrane-Water Interfaces And Distribution Of 2, 4, 6-Trichlorophenol In A Membrane Model System, Isolde Sieder
Electrostatic Interactions At Membrane-Water Interfaces And Distribution Of 2, 4, 6-Trichlorophenol In A Membrane Model System, Isolde Sieder
Dissertations and Theses
It is generally accepted that biological membranes consist of a lipid bilayer matrix with proteins incorporated into the lipid bilayer. Typically, these membranes are negatively charged due to the presence of negatively charged lipids in the bilayer as well as negatively charged molecular groups on proteins. Biologically active molecules, such as environmental pollutants, enter the membrane from the aqueous phase by adsorption or partitioning into the lipid bilayer. The thesis consists of two parts. Part I is a computational study of spatial distribution of electric potential in the aqueous portion of the membrane-water interface using two models of charge distribution: …
Coherent Excitation Of The Singlet-Triplet Mixed 1s4f State Of Helium, Jingbo Wang, J. F. Williams, Andris T. Stelbovics, John E. Furst, Don H. Madison
Coherent Excitation Of The Singlet-Triplet Mixed 1s4f State Of Helium, Jingbo Wang, J. F. Williams, Andris T. Stelbovics, John E. Furst, Don H. Madison
Physics Faculty Research & Creative Works
In this paper, we present a detailed theoretical description for the coherent electron-impact excitation, the subsequent time evolution, and the cascading decay process of the singlet-triplet mixed 1s4f state of helium. The excitation amplitude and phase of each sublevel of this state are related to measurable coincidence intensities and polarizations of the emitted photons. It is found that the intensity and polarization of the emitted photons are time modulated due to the singlet and triplet mixing in the 1s4f state.