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101.
L.J.S. Halloran 《Optics Communications》2009,282(4):554-557
We have measured the isotope shift between 41K and 39K in the 4s1/2 → 5p1/2 transition at 405 nm using saturation spectroscopy. Our measured isotope shift is 456.1 ± 0.8 MHz, implying a residual isotope shift (sum of specific mass shift and field shift) of −52.7 ± 0.8 MHz. We deduce a specific mass shift of −40 ± 5 MHz, which would imply that the 5p1/2 state has a considerably larger specific mass shift than the 4p1/2 state. We have in addition measured the 5p1/2 hyperfine splitting for 41K. 相似文献
102.
F.C. Charlwood K. Baczynska J. Billowes P. Campbell B. Cheal T. Eronen D.H. Forest A. Jokinen T. Kessler I.D. Moore H. Penttilä R. Powis M. Rüffer A. Saastamoinen G. Tungate J. Äystö 《Physics letters. [Part B]》2009
Radioisotopes of molybdenum have been studied using laser spectroscopy techniques at the IGISOL facility, University of Jyväskylä. Differences in nuclear charge radii have been determined for neutron deficient isotopes 90,91Mo and neutron rich isotopes 102–106,108Mo (and all stable isotopes). A smooth transition in the mean square charge radii is observed as the neutron number increases with no sudden shape change observed in the region around N=60. As N increases, the nuclear deformation appears to go beyond a maximum and a fall off at N=66 is observed. The magnetic moments of the odd isotopes 91,103,105Mo are also determined. 相似文献
103.
We discuss the high-temperature electronic and thermal properties of an icosahedral quasicrystal within the framework of the fractional multicomponent Fermi-surface model. When intervalley electron-phonon scattering sets in above a characteristic temperature T∗ of the order of the Debye temperature ΘD the quasicrystal becomes more “metallic”. In this regime the electrical conductivity and the electronic contribution to the thermal conductivity vary as T and T2, respectively. We predict that at elevated temperatures the electronic specific heat will vary faster than γT and the low-frequency Drude-type component of the optical conductivity σ1(ω) will gain weight. 相似文献
104.
Absolute frequency measurement of iodine lines with a femtosecond optical synthesizer 总被引:2,自引:0,他引:2
R. Holzwarth A.Yu. Nevsky M. Zimmermann Th. Udem T.W. Hänsch J. von Zanthier H. Walther J.C. Knight W.J. Wadsworth P.St.J. Russell M.N. Skvortsov S.N. Bagayev 《Applied physics. B, Lasers and optics》2001,73(3):269-271
We have used a single laser femtosecond optical frequency synthesizer together with a widely tunable Nd:YAG laser to measure
the absolute frequency of several absorption lines in molecular iodine around 532 nm. The use of two different repetition
frequencies allows us to determine the number of modes used for the frequency measurement unambiguously. The lines also provide
data for the determination of improved ro-vibrational constants of the iodine molecule.
Received: 3 July 2001 / Published online: 19 September 2001 相似文献
105.
A general phenomenological reaction-diffusion model for flow-induced phase transitions in complex fluids is presented. The
model consists of an equation of motion for a nonconserved composition variable, coupled to a Newtonian stress relation for
the reactant and product species. Multivalued reaction terms allow for different homogeneous phases to coexist with each other,
resulting in banded composition and shear rate profiles. The one-dimensional equation of motion is evolved from a random initial
state to its final steady state. We find that the system chooses banded states over homogeneous states, depending on the shape
of the stress constitutive curve and the magnitude of the diffusion coefficient. Banding in the flow gradient direction under
shear rate control is observed for shear-thinning transitions, while banding in the vorticity direction under stress control
is observed for shear-thickening transitions.
Received 1 April 2001 and Received in final form 16 June 2001 相似文献
106.
T. Schaub J. Delahaye C. Berger H. Guyot R. Belkhou A. Taleb-Ibrahimi Y. Calvayrac 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,20(2):183-188
High resolution photoemission measurements performed at low temperatures on a single-grained sample of the AlPdMn icosahedral
phase show that the density of states N(E) strongly depends on the nature of the surface. For an ordered quasicrystalline surface, prepared by Ar etching and ultra
high vacuum annealing, a dip feature is observed in N(E) near the Fermi level, which energy dependence can be analyzed with a simple square-root power law. By contrast, N(E) varies only little with energy both for a disordered surface and a crystalline surface of the same sample. A sharp Fermi
edge is then clearly observed. This shows that the metallic character of the surface of a quasicrystal is strongly reduced
when the surface presents a quasicrystalline ordering.
Received 19 February 2000 and Received in final form 6 November 2000 相似文献
107.
J. Benlliure P. Armbruster M. Bernas C. Böckstiegel S. Czajkowski C. Donzaud H. Geissel A. Heinz C. Kozhuharov P. Dessagne G. Münzenberg M. Pfützner C. Stéphan K.-H. Schmidt K. Sümmerer W. Schwab L. Tassan-Got B. Voss 《The European Physical Journal A - Hadrons and Nuclei》1998,2(2):193-198
Projectile fragmentation of 238U in a lead target was investigated at a bombarding energy of 750 A MeV. Isotopic production cross sections of about 250 different projectile fragments in the element range Z= 30–53 were measured with the FRagment Separator (FRS). The magnetic selection and the kinematical analysis of the measured
isotopes allowed to disentangle fission and fragmentation residues. The mass loss of these residues indicates a violent collision
where a large amount of energy is dissipated. The position of the fragmentation corridor defined by the measured residues
was used to determine an effective proton-evaporation barrier.
Received: 3 October 1997 / Revised version: 27 February 1998 相似文献
108.
C. Affolderbach C. Andreeva S. Cartaleva T. Karaulanov G. Mileti D. Slavov 《Applied physics. B, Lasers and optics》2005,80(7):841-848
We present a novel scheme for reducing the AC Stark effect in optical-microwave double-resonance spectroscopy and its application for efficient suppression of the light-shift-related instabilities in laser-pumped gas-cell atomic clocks. The method uses a multi-frequency pump light field that can be easily produced by frequency modulation of the single-frequency pump laser. We show theoretically that variations of the light shift with both laser frequency and light intensity can be strongly suppressed with properly chosen pump light spectra. Suitable modulation parameters can be found for both the case of pure frequency modulation as well as for pump light spectra showing amplitude-modulation contributions, as usually found for current modulation of diode lasers. We experimentally demonstrate the method for a Rb atomic clock using a frequency-modulated distributed Bragg-reflector laser diode as pump light source. 相似文献
109.
N. C. Wong 《Applied physics. B, Lasers and optics》1995,61(2):143-149
A method for building an optical-to-microwave frequency chain and for measuring optical frequencies relative to the cesium primary frequency standard is described. Based on optical frequency division via parametric oscillators, the concept is to generate two known ratios (1/2 and 4/9) of an optical calibration frequencyf
1 whose frequency difference is measured relative to the cesium clock. The (1/2) ratio is obtained by either a 2:1 frequency division off
1 or second-harmonic generation of (l/2)f
1. The (4/9) ratio off
1 can be generated with a 3:1 frequency divider driven by a second laser atf
2 that is chosen to be near (2/3)f
1, which in turn is obtained with af
1-pumped 3:1 frequency divider. A set of auxiliary Optical Parametric Oscillators (OPOs) with outputs centered at (1/2)f
1 is used to facilitate the difference-frequency measurement between the two ratios. A practical configuration utilizing a YAG and a Ti: Al2O3 laser and its application to a number of precision measurements of interest are presented. 相似文献
110.
T. Grenet M.C. Cheynet 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,13(4):701-705
We present the results of an electron energy loss spectroscopy (EELS) investigation of the icosahedral quasicrystals i-Al-Cu-Fe,
i-Al-Pd-Mn and i-Al-Pd-Re. The spectra of the three systems studied are very similar. Their main contribution comes from a
broad plasmon like peak, which can be interpreted as an “s-p" electron plasmon damped by “d" electron interband transitions. We show that it is similar to those found in other simple crystalline aluminum-transition
metal alloys, so that no specificity related to the quasicrystalline order of the alloys dominates.
Received 3 November 1998 and Received in final form 16 July 1999 相似文献