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51.
R.J. Hendricks D.M. Grant P.F. Herskind A. Dantan M. Drewsen 《Applied physics. B, Lasers and optics》2007,88(4):507-513
An experimental demonstration of a novel all-optical technique for loading ion traps, which has particular application to
microtrap architectures, is presented. The technique is based on photoionisation of an atomic beam created by pulsed laser
ablation of a calcium target, and provides improved temporal control compared to traditional trap loading methods. Ion loading
rates as high as 125 ions per second have so far been observed. Also described are observations of trap loading where Rydberg
state atoms are photoionised by the ion Doppler cooling laser.
PACS 32.80.Fb; 32.80.Dz; 39.10.+j; 52.38.Mf 相似文献
52.
K. Petersen N. Thrane G. Trumpy R. W. Hendricks 《Applied Physics A: Materials Science & Processing》1976,10(1):85-90
We have measured the lifetimes of positrons in an aluminum single crystal which was irradiated to a fast neutron fluence of 1.5·1021 n/cm2 (>0.18 MeV) at 50°C. These irradiation conditions produced 4.2·1014 voids/cm3 with a mean diameter of 330 Å, as determined by both small-angle x-ray scattering and transmission electron microscopy. The positron lifetime spectra were resolved into three lifetime components of 100, 300, and 500 ps. The short lifetime component is a result of fast trapping of positrons by the voids; the long lifetime components result from annihilations within the voids. The intensity of the long lifetime components increases with temperature in the range 80 to 300 K and supports the model of a positron state at the void surface. The positron diffusion coefficient appears to have aT 1/2-dependence. A magnetic quenching experiment shows no indication of positronium formation. Finally, an isochronal heat treating sequence shows that the voids anneal out between 200 and 300°C, and that the lifetime spectrum after annealing is described by a single component of 170 ps, the observed lifetime in unirradiated aluminum. 相似文献
53.
Paul A. Westbrook John F. Fellers Robert W. Hendricks J. S. Lin 《Journal of Polymer Science.Polymer Physics》1983,21(6):969-982
A small-angle x-ray scattering (SAXS) study of the relaxed craze structure in polystyrene was performed using the Oak Ridge National Laboratory 10-m SAXS facility. Coupled with known results from transmission electron microscopy studies, the SAXS patterns can be interpreted as scattering from an open-cell foam with void spaces interspersed among the fibrils. Results have shown the scattering centers in crazed polystyrene can be modeled as cylinders the axes of symmetry of which are parallel to the tensile axes. Scattering centers are bimodal in their size distribution, with aspect ratios of 1.0 and 2.6. Crazes in lower-molecular-weight polystyrene have more and larger scattering centers than crazes in higher-molecular-weight polystyrene, while variations in strain rate and test temperature during craze formation have no effect on the relaxed craze morphology. A comparison of SAXS patterns from polystyrene and polycarbonate indicates that the morphologies of their respective crazes are significantly different. 相似文献
54.
J. S. Lin R. W. Hendricks J. M. Schultz M. J. McCready 《Journal of Polymer Science.Polymer Physics》1982,20(8):1365-1369
Absolute intensity measurements of a dynamic small-angle x-ray scattering from a linear polyethylene were carried out during polymer crystallization from melt in a temperature range of 113.5° to 124.5°C. The mean-square modulation of the electron density over the irradiated volume was evaluated and the feasibility of dynamic experimentation for crystallization kinetic analysis was established. The results provide an absolute value of mass density of the amorphous phase of a semicrystalline polymer at the crystallization temperature. 相似文献
55.
Sedgwick MA Trujillo AM Hendricks N Levinger NE Crans DC 《Langmuir : the ACS journal of surfaces and colloids》2011,27(3):948-954
Dynamic light scattering and NMR spectroscopic experimental evidence suggest the coexistence of two compositionally different self-assembled particles in solution. The self-assembled particles form in solutions containing water, Aerosol OT (AOT, sodium bis(2-ethylhexyl) sulfosuccinate) surfactant, and cholesterol in cyclohexane. In a similar series of studies carried out in 1-octanol only one aggregate type, that is, reverse micelles, is observed. Dynamic light scattering measurements reveal the presence of two different types of aggregates in the microemulsions formed in cyclohexane, demonstrating the coexistence of two compositionally distinct structures with very similar Gibbs energies. One particle type consists of standard AOT reverse micelles while the second type of particle consists of submicellar aggregates including cholesterol as well as small amounts of AOT and water. In microemulsions employing 1-octanol as the continuous medium, AOT reverse micelles form in a dispersed solution of cholesterol in 1-octanol. Although the size distribution of self-assembled particles is well-known for many different systems, evidence for simultaneous formation of two distinctly sized particles in solution that are chemically different is unprecedented. The ability to form microemulsion solutions that contain coexisting particles may have important applications in drug formulation and administration, particularly as applied to drug delivery using cholesterol as a targeting agent. 相似文献
56.
Spencer T.A. Davis C.E. Hendricks K.J. Agee F.J. Gilgenbach R.M. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1996,24(3):630-635
We report the first gyrotron-backward-wave oscillator experiments which utilize a high-current (1-4 kA) high-voltage (300-500 keV) annular electron beam. The experiment was designed to operate in the TE01 backward wave mode. Radio frequency extracted power was 0.1-4 MW, with pulselengths of 80-500 ns. Experimental results suggest the possibility of competition with the TE21 backward wave mode. Frequency spectrum measurements have shown a wide content of frequencies during the voltage pulse, an undesirable result for use in narrow-band devices 相似文献
57.
The effect of riblets on laminar to turbulent transition 总被引:2,自引:0,他引:2
Experiments conducted on the effect of riblets on the laminar-to-turbulent transition of a flat plate in a water tunnel are reported. Transition was determined using a Laser Doppler Velocimeter (LDV). A smooth reference surface was compared to five riblet surfaces for a range of Reynolds numbers. Smooth surface transition Reynolds number was about 2.75 × 106. All of the five tested riblet surfaces had lower transition Reynolds numbers. A critical roughness Reynolds number of about 6 was determined for one of the riblet surfaces. This is much lower than the generally accepted value of 25, considered safe for distributed roughness. 相似文献
58.
Haleden Chiririwa John R. Moss Denver Hendricks Reinout Meijboom Alfred Muller 《Transition Metal Chemistry》2013,38(2):165-172
Palladium(II) complexes have been obtained from the reactions of the iminophosphine ligands, (L1–L7), respectively, with [PdCl2(COD)] and [PdMeCl(COD)] in CH2Cl2 at room temperature. The palladium(II) complexes were characterised using elemental analysis, electro spray ionisation–mass spectrometry (ESI–MS), NMR (1H and 31P), IR spectroscopy and X-ray diffraction studies. Single-crystal X-ray diffraction analysis for complexes 2, 7 and 8 revealed that the complexes exhibited a slightly distorted square planar geometry. In vitro cytotoxic study results show that the palladium complexes exhibit moderate activity and block the proliferation of WHCO1 cells with an IC50 range of 19.02–45.27 μM, and IC50 range of 10.03–68.54 μM for the KYSE450 cell lines. 相似文献
59.
60.
J. P. Allain M. Nieto-Perez M. R. Hendricks P. Zink C. Metzmacher K. Bergmann 《Applied Physics A: Materials Science & Processing》2010,100(1):231-237
Sn+ irradiations of Ru single-layer mirrors (SLM) simulate conditions of fast-Sn ion exposure in high-intensity 13.5 nm lithography
lamps. Ultra-shallow implantation of Sn is measured down to 1–1.5 nm depth for energies between 1–1.3 keV at near-normal incident
angles on Ru mirror surfaces. The Sn surface concentration reaches an equilibrium of 55–58% Sn/Ru for near-normal incidence
and 36–38% for grazing incidence at approximately 63 degrees with respect to the mirror surface normal. The relative reflectivity
at 13.5 nm at 15-degree incidence was measured in-situ during Sn+ irradiation. For near-normal Sn+ exposures the reflectivity is measured to decrease between 4–7% for a total Sn fluence of 1016 cm−2. Theoretical Fresnel reflectivity modeling shows for the same fluence assuming all Sn atoms form a layer on the Ru mirror
surface, that the reflectivity loss should be between 15–18% for this dose. Ex-situ absolute 13.5 nm reflectivity data corroborate
these results, indicating that implanted energetic Sn atoms mixed with Ru reflect 13.5-nm light differently than theoretically
predicted by Fresnel reflectivity models. 相似文献