56 research outputs found
Recoil-free spectroscopy of neutral Sr atoms in the Lamb-Dicke regime
We have demonstrated a recoil-free spectroscopy on the
transition of strontium atoms confined in a one-dimensional optical lattice. By
investigating the wavelength and polarization dependence of the ac Stark shift
acting on the and states, we determined the {\it
magic wavelength} where the Stark shifts for both states coincide. The
Lamb-Dicke confinement provided by this Stark-free optical lattice enabled the
measurement of the atomic spectrum free from Doppler as well as recoil shifts.Comment: 5pages, 4figure
Induction of embryonal carcinoma cell differentiation by deferoxamine, a potent therapeutic iron chelator
AbstractWe investigated the effects of deferoxamine on the differentiation of embryonal carcinoma F9 cells. Deferoxamine, a widely used therapeutic agent for thalassemia and iron overload, was found to induce F9 cell differentiation and to have some unique characteristics compared with other chelators, hinokitiol and dithizone, which were previously reported to induce differentiation of these cells. This hydrophilic agent induced reversible differentiation as did sodium butyrate, whereas other chelators did not. However, morphological features of the cells after deferoxamine-induced differentiation were similar to those of cells incubated with the other chelators. The differentiation-inducing activity of deferoxamine was abolished by preincubation with Fe3+ ions, similarly to the other chelators examined. Moreover, cell proliferation was inhibited by treatment with this agent, and the numbers of cells in the colonies were reduced by apoptosis. Based on these results, we conclude that deferoxamine induces differentiation and apoptosis of F9 cells via chelation of extracellular and/or intracellular Fe3+ ions
Precision spectroscopy and density-dependent frequency shifts in ultracold Sr
By varying the density of an ultracold Sr sample from cm
to cm, we make the first definitive measurement of the
density-related frequency shift and linewidth broadening of the -
optical clock transition in an alkaline earth system. In addition, we
report the most accurate measurement to date of the Sr
optical clock transition frequency. Including a detailed analysis of systematic
errors, the frequency is () Hz.Comment: 4 pages, 4 figures, 1 table. submitte
Narrow Line Cooling: Finite Photon Recoil Dynamics
We present an extensive study of the unique thermal and mechanical dynamics
for narrow-line cooling on the 1S0 - 3P1 88Sr transition. For negative
detuning, trap dynamics reveal a transition from the semiclassical regime to
the photon-recoil-dominated quantum regime, yielding an absolute minima in the
equilibrium temperature below the single-photon recoil limit. For positive
detuning, the cloud divides into discrete momentum packets whose alignment
mimics lattice points on a face-centered-cubic crystal. This novel behavior
arises from velocity selection and "positive feedback" acceleration due to a
finite number of photon recoils. Cooling is achieved with blue-detuned light
around a velocity where gravity balances the radiative force.Comment: 4 pages, 3 figures, Phys. Rev. Lett., in pres
Narrow Line Cooling and Momentum-Space Crystals
Narrow line laser cooling is advancing the frontier for experiments ranging
from studies of fundamental atomic physics to high precision optical frequency
standards. In this paper, we present an extensive description of the systems
and techniques necessary to realize 689 nm 1S0 - 3P1 narrow line cooling of
atomic 88Sr. Narrow line cooling and trapping dynamics are also studied in
detail. By controlling the relative size of the power broadened transition
linewidth and the single-photon recoil frequency shift, we show that it is
possible to continuously bridge the gap between semiclassical and quantum
mechanical cooling. Novel semiclassical cooling process, some of which are
intimately linked to gravity, are also explored. Moreover, for laser
frequencies tuned above the atomic resonance, we demonstrate momentum-space
crystals containing up to 26 well defined lattice points. Gravitationally
assisted cooling is also achieved with blue-detuned light. Theoretically, we
find the blue detuned dynamics are universal to Doppler limited systems. This
paper offers the most comprehensive study of narrow line laser cooling to date.Comment: 14 pages, 19 figure
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