Mobile impurities interacting with a few one-dimensional lattice bosons

We report a comprehensive study of the ground-state properties of one and two bosonic impurities immersed in small one-dimensional optical lattices loaded with a few interacting bosons. We model the system with a two-component Bose-Hubbard model and solve the problem numerically by means of the exact diagonalization method. We report polaron and bipolaron energies across the superfluid to Mott-insulator transition and confirm the formation of bipolaron bound states induced by repulsive interactions. In particular, we found that an insulator bath induces tightly bound bipolarons, whereas a superfluid bath induces shallower bound states.Comment: 22 pages, 13 figure

CHARACTERIZATION OF RF AND DC MAGNETRON REACTIVE SPUTTERED TiO 2 THIN FILMS FOR GAS SENSORS

This study presents the technology for prep aring and characterization of titanium oxide thin films with proper ties suitable for gas sensors. For preparing the samples the reactive radio frequency (RF) and direct current (DC) magnetron sputtering methods were used. The composition and microstructure of the films were studied by X-ray photoelectron spectroscopy (XPS), X-ray diff raction (XRD) and Raman spectroscopy, the surface of the films was observed applying high-resolution scanning electron microscopy (SEM). For measuring the thickness and identifying the refractive indices of the films laser ellipsometry was used. The research was focuse d on the sensing behavior of the sputtered titania thin films applying quartz crystal microbalance (QCM) method, which allows detection of mass changes in the nanogram range. Prototype QCM sensors with TiO 2 thin films were made by our team and tested for sensitivity to NH 3 and NO 2 . These films even in as-deposited state and without heating th e substrates show good sensitivity. Additional thermal treatment is not necessary, making manufacturing of QCM gas sensor simple and cost-effective, as it is fully compatible with the technology for producing the initial resonator. The sorption is fully reversible and the studied TiO 2 films are stable, which makes them capable for meas urements for long terms

Characterization of thin MoO3 films formed by RF and DC-magnetron reactive sputtering for gas sensor applications

The present work discusses a technology f or deposition and characterization of thin molybdenum oxide (MoO x , MoO 3 ) films studied for gas sensor applications. T he samples were produced by reactive radio - frequency (RF) and direct c urrent (DC) magnetron sputtering. The composition and microstructure of the films were studied by XPS , XRD and Raman spectroscopy, the morphology , using high resolution SEM. T he research was focused on the sensing properties of the sputtered thin MoO 3 films. Highly sensitive gas sensor s were implemented by depositing films of various thicknesses on quartz resonators. Making use of the quartz crystal microbalance (QCM) method , the se sensors we re capable of detect ing chan ges in the molecular range. Prototype QCM structures with thin MoO 3 films were tested for sensitivity to NH 3 and NO 2 . E ven in as - deposited state and without heating the substrates, these films show ed good sensitivity . Moreover , no a dditional thermal treatment is necessary, which makes the production of such QCM gas sensor s simple and cost - effective, as it is fu lly compatible wit h the technology for producing t he initial resonator . Т he films are sensitive at room temperature and can reg ister concentrations as low as 50 ppm . The sorption is fully reversible , the films are stable and capable of long - term measuremen ts

PERCEPTION OF Er-YAG LASER DENTAL CARIES TREATMENT IN ADOLESCENTS - A CLINICAL EVALUATION.

The aim of this study was to evaluate adolescents’ acceptance and pain perception of Er-YAG laser preparation in comparison to conventional mechanical preparation. Material and methods: Forty four adolescents between the age of 16 and 18 years with bilateral matched pairs of carious permanent molars participated in this study. In each patient one of the 2 cavities was prepared conventionally, the other with the Er-YAG laser. All cavities were restored with light-cured composite resin following the application of acid etch and a bonding agent. The patients were instructed to rate pain (sensitivity) during treatment according to visual analogue scale and to decide which method they would prefer for their future caries treatment. Results: The patients rated lower pain perception during laser treatment. It was found that 86.36 % of the adolescents indicated that they would prefer the Er:YAG laser preparation for further caries treatment. Conclusion: The application of the Er-YAG laser for carious tissue removal, compared to conventional mechanical preparation, is perceived as more comfortable and the adolescents prefer it for a future treatment

Precision Measurement of 11Li moments: Influence of Halo Neutrons on the 9Li Core

The electric quadrupole moment and the magnetic moment of the 11Li halo nucleus have been measured with more than an order of magnitude higher precision than before, |Q| = 33.3(5)mb and mu=3.6712(3)mu_N, revealing a 8.8(1.5)% increase of the quadrupole moment relative to that of 9Li. This result is compared to various models that aim at describing the halo properties. In the shell model an increased quadrupole moment points to a significant occupation of the 1d orbits, whereas in a simple halo picture this can be explained by relating the quadrupole moments of the proton distribution to the charge radii. Advanced models so far fail to reproduce simultaneously the trends observed in the radii and quadrupole moments of the lithium isotopes.Comment: 4 pages, 4 figures, 1 tabl

Optical measurements of electrophoretic suspension kinetics

Electrophoretic deposition (EPD) was originally used for formation of coatings, e. g. in the automotive industry. Recently EPD is successfully utili zed for thin film preparation with an app lication in the optics and electronics. This paper investigates the process of the suspension formation and aggregation by ultraviolet and visible spectroscopy (UV- VIS) spectroscopy and Dynamic Light Scattering (DLS) methods. The suspensions were formed by a precipitation of solution of poly[2-methoxy-5-(3 ′ ,7 ′ -dimethyloctyloxy)-1,4-phenylenevinylene] in toluene using acetonitrile as a precipitator. It could be concluded that the progressive suspension particle growth observed by DLS affects regularly the first derivative of the UV-VIS spectra. By a comparison of the results obtained by both methods it could be seen that UV-VIS spectroscopy combined with the spline method could be successfully used for an estimation of electrophoretic suspensions

Ferromagnetism and Lattice Distortions in the Perovskite YTiO3_3

The thermodynamic properties of the ferromagnetic perovskite YTiO$_3$ are investigated by thermal expansion, magnetostriction, specific heat, and magnetization measurements. The low-temperature spin-wave contribution to the specific heat, as well as an Arrott plot of the magnetization in the vicinity of the Curie temperature $T_C\simeq27$ K, are consistent with a three-dimensional Heisenberg model of ferromagnetism. However, a magnetic contribution to the thermal expansion persists well above $T_C$, which contrasts with typical three-dimensional Heisenberg ferromagnets, as shown by a comparison with the corresponding model system EuS. The pressure dependences of $T_C$ and of the spontaneous moment $M_s$ are extracted using thermodynamic relationships. They indicate that ferromagnetism is strengthened by uniaxial pressures $\mathbf{p}\parallel \mathbf{a}$ and is weakened by uniaxial pressures $\mathbf{p}\parallel \mathbf{b},\mathbf{c}$ and hydrostatic pressure. Our results show that the distortion along the $a$- and $b$-axes is further increased by the magnetic transition, confirming that ferromagnetism is favored by a large GdFeO$_3$-type distortion. The c-axis results however do not fit into this simple picture, which may be explained by an additional magnetoelastic effect, possibly related to a Jahn-Teller distortion.Comment: 12 pages, 13 figure

Spectroscopic distinction between the normal state pseudogap and the superconducting gap of cuprate high T_{c} superconductors

We report on broad-band infrared ellipsometry measurements of the c-axis conductivity of underdoped RBa_{2}Cu_{3}O_{7-d} (R=Y, Nd, and La) single crystals. Our data provide a detailed account of the spectral weight (SW) redistributions due to the normal state pseudogap (PG) and the superconducting (SC) gap. They show that these phenomena involve different energy scales, exhibit distinct doping dependencies and thus are likely of different origin. In particular, the SW redistribution in the PG state closely resembles the one of a conventional charge- or spin density wave (CDW or SDW) system.Comment: 4 pages, 4 figure