Ultra--cold gases and the detection of the Earth's rotation: Bogoliubov space and gravitomagnetism

The present work analyzes the consequences of the gravitomagnetic effect of the Earth upon a bosonic gas in which the corresponding atoms have a non--vanishing orbital angular momentum. Concerning the ground state of the Bogoliubov space of this system we deduce the consequences, on the pressure and on the speed of sound, of the gravitomagnetic effect. We prove that the effect on a single atom is very small, but we also show that for some thermodynamical properties the consequences scale as a non--trivial function of the number of particles.Comment: 4 page

A new capacitive sensor for displacement measurement in a surface force apparatus

We present a new capacitive sensor for displacement measurement in a Surface Forces Apparatus (SFA) which allows dynamical measurements in the range of 0-100 Hz. This sensor measures the relative displacement between two macroscopic opaque surfaces over periods of time ranging from milliseconds to in principle an indefinite period, at a very low price and down to atomic resolution. It consists of a plane capacitor, a high frequency oscillator, and a high sensitivity frequency to voltage conversion. We use this sensor to study the nanorheological properties of dodecane confined between glass surfaces.Comment: 7 pages, 8 figure

Non-adiabatic effects during the dissociative adsorption of O2 at Ag(111)? A first-principles divide and conquer study

We study the gas-surface dynamics of O2 at Ag(111) with the particular objective to unravel whether electronic non-adiabatic effects are contributing to the experimentally established inertness of the surface with respect to oxygen uptake. We employ a first-principles divide and conquer approach based on an extensive density-functional theory mapping of the adiabatic potential energy surface (PES) along the six O2 molecular degrees of freedom. Neural networks are subsequently used to interpolate this grid data to a continuous representation. The low computational cost with which forces are available from this PES representation allows then for a sufficiently large number of molecular dynamics trajectories to quantitatively determine the very low initial dissociative sticking coefficient at this surface. Already these adiabatic calculations yield dissociation probabilities close to the scattered experimental data. Our analysis shows that this low reactivity is governed by large energy barriers in excess of 1.1 eV very close to the surface. Unfortunately, these adiabatic PES characteristics render the dissociative sticking a rather insensitive quantity with respect to a potential spin or charge non-adiabaticity in the O2-Ag(111) interaction. We correspondingly attribute the remaining deviations between the computed and measured dissociation probabilities primarily to unresolved experimental issues with respect to surface imperfections.Comment: 18 pages including 6 figure

Stability and electronic structure of the complex K2_2PtCl6_6 structure-type hydrides

The stability and bonding of the ternary complex K$_2$PtCl$_6$ structure hydrides is discussed using first principles density functional calculations. The cohesion is dominated by ionic contributions, but ligand field effects are important, and are responsible for the 18-electron rule. Similarities to oxides are discussed in terms of the electronic structure. However, phonon calculations for Sr$_2$RuH$_6$ also show differences, particularly in the polarizability of the RuH$_6$ octahedra. Nevertheless, the yet to be made compounds Pb$_2$RuH$_6$ and Be$_2$FeH$_6$ are possible ferroelectrics. The electronic structure and magnetic properties of the decomposition product, FeBe$_2$ are reported. Implications of the results for H storage are discussed

Immersed nano-sized Al dispersoids in an Al matrix; effects on the structural and mechanical properties by Molecular Dynamics simulations

We used molecular dynamics simulations based on a potential model in analogy to the Tight Binding scheme in the Second Moment Approximation to simulate the effects of aluminum icosahedral grains (dispersoids) on the structure and the mechanical properties of an aluminum matrix. First we validated our model by calculating several thermodynamic properties referring to the bulk Al case and we found good agreement with available experimental and theoretical data. Afterwards, we simulated Al systems containing Al clusters of various sizes. We found that the structure of the Al matrix is affected by the presence of the dispersoids resulting in well ordered domains of different symmetries that were identified using suitable Voronoi analysis. In addition, we found that the increase of the grain size has negative effect on the mechanical properties of the nanocomposite as manifested by the lowering of the calculated bulk moduli. The obtained results are in line with available experimental data.Comment: 15 pages, 8 figures. Submitted to J. Phys: Condens. Matte

Frequency-shift vs phase-shift characterization of in-liquid quartz crystal microbalance applications

The improvement of sensitivity in quartz crystal microbalance (QCM) applications has been addressed in the last decades by increasing the sensor fundamental frequency, following the increment of the frequencymass sensitivity with the square of frequency predicted by Sauerbrey. However, this sensitivity improvement has not been completely transferred in terms of resolution. The decrease of frequency stability due to the increase of the phase noise, particularly in oscillators, made impossible to reach the expected resolution. A new concept of sensor characterization at constant frequency has been recently proposed. The validation of the new concept is presented in this work. An immunosensor application for the detection of a low molecular weight contaminant, the insecticide carbaryl, has been chosen for the validation. An, in principle, improved version of a balanced-bridge oscillator is validated for its use in liquids, and applied for the frequency shift characterization of the QCM immunosensor application. The classical frequency shift characterization is compared with the new phase-shift characterization concept and system proposed. © 2011 American Institute of Physics.The authors are grateful to the Spanish Ministry of Science and Technology for the financial support to this research under contract reference AGL2009-13511, and to the company Advanced Wave Sensors S. L. (www.awsensors.com) for the help provided in the development of some parts of this work.Montagut Ferizzola, YJ.; García Narbón, JV.; Jiménez Jiménez, Y.; March Iborra, MDC.; Montoya Baides, Á.; Arnau Vives, A. (2011). Frequency-shift vs phase-shift characterization of in-liquid quartz crystal microbalance applications. Review of Scientific Instruments. 82(6):1-14. https://doi.org/10.1063/1.3598340S114826Sauerbrey, G. (1959). 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Biomacromolecules, 3(6), 1170-1178. doi:10.1021/bm0255490Höök, F., Ray, A., Nordén, B., & Kasemo, B. (2001). Characterization of PNA and DNA Immobilization and Subsequent Hybridization with DNA Using Acoustic-Shear-Wave Attenuation Measurements. Langmuir, 17(26), 8305-8312. doi:10.1021/la0107704Ben-Dov, I., Willner, I., & Zisman, E. (1997). Piezoelectric Immunosensors for Urine Specimens ofChlamydia trachomatisEmploying Quartz Crystal Microbalance Microgravimetric Analyses. Analytical Chemistry, 69(17), 3506-3512. doi:10.1021/ac970216sNirschl, M., Blüher, A., Erler, C., Katzschner, B., Vikholm-Lundin, I., Auer, S., … Mertig, M. (2009). Film bulk acoustic resonators for DNA and protein detection and investigation of in vitro bacterial S-layer formation. Sensors and Actuators A: Physical, 156(1), 180-184. doi:10.1016/j.sna.2009.02.021Fung, Y. S., & Wong, Y. Y. (2001). Self-Assembled Monolayers as the Coating in a Quartz Piezoelectric Crystal Immunosensor To Detect Salmonella in Aqueous Solution. Analytical Chemistry, 73(21), 5302-5309. doi:10.1021/ac010655yZhou, X., Liu, L., Hu, M., Wang, L., & Hu, J. (2002). Detection of hepatitis B virus by piezoelectric biosensor. Journal of Pharmaceutical and Biomedical Analysis, 27(1-2), 341-345. doi:10.1016/s0731-7085(01)00538-6Gabl, R., Green, E., Schreiter, M., Feucht, H. D., Zeininger, H., Primig, R., … Wersing, W. (s. f.). Novel integrated FBAR sensors: a universal technology platform for bio- and gas-detection. Proceedings of IEEE Sensors 2003 (IEEE Cat. No.03CH37498). doi:10.1109/icsens.2003.1279132Gabl, R., Feucht, H.-D., Zeininger, H., Eckstein, G., Schreiter, M., Primig, R., … Wersing, W. (2004). First results on label-free detection of DNA and protein molecules using a novel integrated sensor technology based on gravimetric detection principles. 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IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 53(11), 2095-2100. doi:10.1109/tuffc.2006.149Wingqvist, G., Bjurström, J., Liljeholm, L., Yantchev, V., & Katardjiev, I. (2007). Shear mode AlN thin film electro-acoustic resonant sensor operation in viscous media. Sensors and Actuators B: Chemical, 123(1), 466-473. doi:10.1016/j.snb.2006.09.028Wingqvist, G., Anderson, H., Lennartsson, C., Weissbach, T., Yantchev, V., & Lloyd Spetz, A. (2009). On the applicability of high frequency acoustic shear mode biosensing in view of thickness limitations set by the film resonance. Biosensors and Bioelectronics, 24(11), 3387-3390. doi:10.1016/j.bios.2009.04.021Harding, G. L. (2001). Mass sensitivity of Love-mode acoustic sensors incorporating silicon dioxide and silicon-oxy-fluoride guiding layers. Sensors and Actuators A: Physical, 88(1), 20-28. doi:10.1016/s0924-4247(00)00491-xWang, Z., Cheeke, J. D. N., & Jen, C. K. (1994). Sensitivity analysis for Love mode acoustic gravimetric sensors. Applied Physics Letters, 64(22), 2940-2942. doi:10.1063/1.111976Kalantar-Zadeh, K., Wlodarski, W., Chen, Y. Y., Fry, B. N., & Galatsis, K. (2003). Novel Love mode surface acoustic wave based immunosensors. Sensors and Actuators B: Chemical, 91(1-3), 143-147. doi:10.1016/s0925-4005(03)00079-0Ogi, H., Naga, H., Fukunishi, Y., Hirao, M., & Nishiyama, M. (2009). 170-MHz Electrodeless Quartz Crystal Microbalance Biosensor: Capability and Limitation of Higher Frequency Measurement. Analytical Chemistry, 81(19), 8068-8073. doi:10.1021/ac901267bA. Arnau, V. Ferrari, D. Soares, and H. Perrot, inPiezoelectric Transducers and Applications, edited by A. Arnau, 2nd ed. (Springer Verlag, Berlin Heidelberg, 2008), ch. 5, pp. 117–186.Eichelbaum, F., Borngräber, R., Schröder, J., Lucklum, R., & Hauptmann, P. (1999). Interface circuits for quartz-crystal-microbalance sensors. Review of Scientific Instruments, 70(5), 2537-2545. doi:10.1063/1.1149788Schröder, J., Borngräber, R., Lucklum, R., & Hauptmann, P. (2001). Network analysis based interface electronics for quartz crystal microbalance. Review of Scientific Instruments, 72(6), 2750-2755. doi:10.1063/1.1370560Doerner, S., Schneider, T., Schroder, J., & Hauptmann, P. (s. f.). Universal impedance spectrum analyzer for sensor applications. Proceedings of IEEE Sensors 2003 (IEEE Cat. No.03CH37498). doi:10.1109/icsens.2003.1279007Rodahl, M., & Kasemo, B. (1996). A simple setup to simultaneously measure the resonant frequency and the absolute dissipation factor of a quartz crystal microbalance. Review of Scientific Instruments, 67(9), 3238-3241. doi:10.1063/1.1147494Rodahl, M., & Kasemo, B. (1996). Frequency and dissipation-factor responses to localized liquid deposits on a QCM electrode. Sensors and Actuators B: Chemical, 37(1-2), 111-116. doi:10.1016/s0925-4005(97)80077-9Barnes, C. (1992). Some new concepts on factors influencing the operational frequency of liquid-immersed quartz microbalances. Sensors and Actuators A: Physical, 30(3), 197-202. doi:10.1016/0924-4247(92)80120-rWessendorf, K. O. (s. f.). The Lever oscillator for use in high resistance resonator applications. 1993 IEEE International Frequency Control Symposium. doi:10.1109/freq.1993.367466Borngraber, R., Schroder, J., Lucklum, R., & Hauptmann, P. (2002). Is an oscillator-based measurement adequate in a liquid environment? IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 49(9), 1254-1259. doi:10.1109/tuffc.2002.1041542Ehahoun, H., Gabrielli, C., Keddam, M., Perrot, H., & Rousseau, P. (2002). Performances and Limits of a Parallel Oscillator for Electrochemical Quartz Crystal Microbalances. Analytical Chemistry, 74(5), 1119-1127. doi:10.1021/ac010883sMartin, S. J., Spates, J. J., Wessendorf, K. O., Schneider, T. W., & Huber, R. J. (1997). 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In-Liquid Sensing of Chemical Compounds by QCM Sensors Coupled With High-Accuracy ACC Oscillator. IEEE Transactions on Instrumentation and Measurement, 55(3), 828-834. doi:10.1109/tim.2006.873792Ferrari, M., Ferrari, V., & Kanazawa, K. K. (2008). Dual-harmonic oscillator for quartz crystal resonator sensors. Sensors and Actuators A: Physical, 145-146, 131-138. doi:10.1016/j.sna.2007.10.087Riesch, C., & Jakoby, B. (2007). Novel Readout Electronics for Thickness Shear-Mode Liquid Sensors Compensating for Spurious Conductivity and Capacitances. IEEE Sensors Journal, 7(3), 464-469. doi:10.1109/jsen.2007.891931Arnau, A., García, J. V., Jimenez, Y., Ferrari, V., & Ferrari, M. (2008). Improved electronic interfaces forAT-cut quartz crystal microbalance sensors under variable damping and parallel capacitance conditions. Review of Scientific Instruments, 79(7), 075110. doi:10.1063/1.2960571Barnes, C. (1991). Development of quartz crystal oscillators for under-liquid sensing. Sensors and Actuators A: Physical, 29(1), 59-69. doi:10.1016/0924-4247(91)80032-kAuge, J., Hauptmann, P., Eichelbaum, F., & Rösler, S. (1994). Quartz crystal microbalance sensor in liquids. Sensors and Actuators B: Chemical, 19(1-3), 518-522. doi:10.1016/0925-4005(93)00983-6Auge, J., Hauptmann, P., Hartmann, J., Rösler, S., & Lucklum, R. (1995). New design for QCM sensors in liquids. Sensors and Actuators B: Chemical, 24(1-3), 43-48. doi:10.1016/0925-4005(95)85010-4Chagnard, C., Gilbert, P., Watkins, A. N., Beeler, T., & Paul, D. W. (1996). An electronic oscillator with automatic gain control: EQCM applications. Sensors and Actuators B: Chemical, 32(2), 129-136. doi:10.1016/0925-4005(96)80121-3Rodriguez-Pardo, L., Fariña, J., Gabrielli, C., Perrot, H., & Brendel, R. (2004). Resolution in quartz crystal oscillator circuits for high sensitivity microbalance sensors in damping media. 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Ultrasensitive quartz crystal microbalance sensors for detection of M13-Phages in liquids. Biosensors and Bioelectronics, 16(9-12), 735-743. doi:10.1016/s0956-5663(01)00220-2Zimmermann, B., Lucklum, R., Hauptmann, P., Rabe, J., & Büttgenbach, S. (2001). Electrical characterisation of high-frequency thickness-shear-mode resonators by impedance analysis. Sensors and Actuators B: Chemical, 76(1-3), 47-57. doi:10.1016/s0925-4005(01)00567-6Sagmeister, B. P., Graz, I. M., Schwödiauer, R., Gruber, H., & Bauer, S. (2009). User-friendly, miniature biosensor flow cell for fragile high fundamental frequency quartz crystal resonators. Biosensors and Bioelectronics, 24(8), 2643-2648. doi:10.1016/j.bios.2009.01.023Bustabad, E. A., Rose, D., Arnau, A., Garcia, G., Rodriguez-Pardo, L., Farina, J., … Lazerges, M. (2009). A biosensor for detection of DNA sequences based on a 50MHz QCM electronic oscillator circuit. 2009 IEEE Sensors. doi:10.1109/icsens.2009.5398346Arnau, A., Montagut, Y., García, J. V., & Jiménez, Y. (2009). A different point of view on the sensitivity of quartz crystal microbalance sensors. Measurement Science and Technology, 20(12), 124004. doi:10.1088/0957-0233/20/12/124004Martin, S. J., Granstaff, V. E., & Frye, G. C. (1991). Characterization of a quartz crystal microbalance with simultaneous mass and liquid loading. Analytical Chemistry, 63(20), 2272-2281. doi:10.1021/ac00020a015Keiji Kanazawa, K., & Gordon, J. G. (1985). The oscillation frequency of a quartz resonator in contact with liquid. Analytica Chimica Acta, 175, 99-105. doi:10.1016/s0003-2670(00)82721-xPax, M., Rieger, J., Eibl, R. H., Thielemann, C., & Johannsmann, D. (2005). Measurements of fast fluctuations of viscoelastic properties with the quartz crystal microbalance. The Analyst, 130(11), 1474. doi:10.1039/b504302fMontrose, M. I. (1998). EMC and the Printed Circuit Board. doi:10.1002/047172310xA. Montoya, A. Ocampo, and C. March, inPiezoelectric Transducers and Applications, edited by A. 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Quasiparticle scattering time in superconducting films: from dirty to clean limit

We study the quasiparticle energy relaxation processes in superconducting Nb films of different thicknesses corresponding to different electron mean free paths in a state far from equilibrium, that is the highly dissipative flux-flow state driven up to the instability point. From the measured current-voltage curves we derive the vortex critical velocity $v^{*}$ for several temperatures. From the $v^{*}(T)$ values, the quasiparticle energy relaxation time $\tau_{\epsilon}$ is evaluated within the Larkin-Ovchinnikov model and numerical calculations of the quasiparticle energy relaxation rates are carried out to support the experimental findings. Besides the expected constant behavior of $\tau_{\epsilon}(T)$ for the dirty samples, we observe a strong temperature dependence of the quasiparticle energy relaxation time in the clean samples. This feature is associated with the increasing contribution from the electron-phonon scattering process as the dirty limit is approached from the clean regime

Surface Plasmon Enhanced Photoconductance of Gold Nanoparticle Arrays with Incorporated Alkane Linkers

We report on a photoconductive gain effect in two-dimensional arrays of gold nanoparticles, in which alkane molecules are inserted. The nanoparticle arrays are formed by a self-assembly process from alkanethiol-coated gold nanoparticles, and subsequently they are patterned on a Si/SiO2 chip by a microcontact printing technique. We find that the photoconductance of the arrays is strongly enhanced at the frequency of the surface plasmon of the nanoparticles. We interpret the observation as a bolometric enhancement of the conductance of the nanoparticle arrays upon excitation of the surface plasmon resonance

Time-dependent fluorescence in nanoconfined solvents: Linear-response approximations and Gaussian statistics

This is the publisher's version, also available electronically from http://scitation.aip.org/content/aip/journal/jcp/135/8/10.1063/1.3626825.The time-dependent fluorescence of a model dye molecule in a nanoconfined solvent is used to test approximations based on the dynamic and static linear-response theories and the assumption of Gaussian statistics. Specifically, the results of nonequilibrium molecular-dynamics simulations are compared to approximate expressions involving time correlation functions obtained from equilibrium simulations. Solvation dynamics of a model diatomic dye molecule dissolved in acetonitrile confined in a spherical hydrophobic cavity of radius 12, 15, and 20 Å is used as the test case. Both the time-dependent fluorescence energy, expressed as the normalized dynamic Stokes shift, and the time-dependent position of the dye molecule after excitation are examined. While the dynamic linear-response approximation fails to describe key aspects of the solvation dynamics, assuming Gaussian statistics reproduces the full nonequilibrium simulations well. The implications of these results are discussed

Coulomb correlation effects in zinc monochalcogenides

Electronic structure and band characteristics for zinc monochalcogenides with zinc-blende- and wurtzite-type structures are studied by first-principles density-functional-theory calculations with different approximations. It is shown that the local-density approximation underestimates the band gap and energy splitting between the states at the top of the valence band, misplaces the energy levels of the Zn-3d states, and overestimates the crystal-field-splitting energy. Regardless of the structure type considered, the spin-orbit-coupling energy is found to be overestimated for ZnO and underestimated for ZnS with wurtzite-type structure, and more or less correct for ZnSe and ZnTe with zinc-blende-type structure. The order of the states at the top of the valence band is found to be anomalous for ZnO in both zinc-blende- and wurtzite-type structure, but is normal for the other zinc monochalcogenides considered. It is shown that the Zn-3d electrons and their interference with the O-2p electrons are responsible for the anomalous order. The typical errors in the calculated band gaps and related parameters for ZnO originate from strong Coulomb correlations, which are found to be highly significant for this compound. The LDA+U approach is by and large found to correct the strong correlation of the Zn-3d electrons, and thus to improve the agreement with the experimentally established location of the Zn-3d levels compared with that derived from pure LDA calculations