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141.
The relative contributions of the partial electron waves emitted in the Auger decay of the Xe* 4d(-1)(5/2)6p(J(*)=1) resonance have been determined by fluorescence polarimetry after excitation with circularly polarized synchrotron radiation. The analysis of circularly polarized fluorescence of the photoion leads to an independent determination of the orientation parameters for all states of the Xe II 5p(4)6p multiplet. The present study provides, in combination with data on the angular distribution and spin polarization of the Auger electrons, complete quantum mechanical information on the resonant Auger decay, i.e., branching ratios and relative phases of the Auger decay amplitudes. 相似文献
142.
MRI and x-ray CT study of spatial distribution of core breakdown in 'Conference' pears 总被引:7,自引:0,他引:7
Lammertyn J Dresselaers T Van Hecke P Jancsók P Wevers M Nicolaï BM 《Magnetic resonance imaging》2003,21(7):805-815
Two non-destructive tomographic techniques, X-ray CT imaging and magnetic resonance imaging (MRI), were applied to study the development of core breakdown disorder in 'Conference' pears (Pyrus communis cv. Conference). This disorder, which is characterized by brown discoloration of the tissue and development of cavities, is induced by elevated CO(2) and decreased O(2) levels during controlled atmosphere storage. Tomographic images of pears stored for 10 months under disorder inducing conditions, were acquired with both techniques and compared to the actual slices. Both X-ray and MRI were able to differentiate between unaffected tissue, brown tissue and cavities. A simple image-processing program, based on threshold values, was developed to determine the area percentage of affected and unaffected tissue as well as the cavity and core area per slice. For all three imaging techniques the area percentage brown tissue per slice increased with the diameter of the pear, but was systematically underestimated by 12% and 6% for, respectively, X-ray and MRI, compared to the actual slices. The area percentage cavity corresponded very well for all techniques. It was also found that the contours of the brown tissue were parallel to the fruit boundaries, suggesting a relation between the disorder symptoms and gas diffusion properties of the fruit. It was concluded that MRI is the most appropriate technique to study the development of core breakdown disorder during postharvest storage in future experiments. 相似文献
143.
Ricciardi MV Enqvist T Pereira J Benlliure J Bernas M Casarejos E Henzl V Kelić A Taïeb J Schmidt KH 《Physical review letters》2003,90(21):212302
Precise momentum distributions of identified projectile fragments, formed in the reactions 238U+Pb and 238U+Ti at 1A GeV, are measured with a high-resolution magnetic spectrometer. With increasing mass loss, the velocities first decrease as expected from previously established systematics, then level off, and finally increase again. Light fragments are on the average even faster than the projectiles. This finding is interpreted as the response of the spectators to the participant blast. The reacceleration of projectile spectators is sensitive to the nuclear mean field and provides a new tool for investigating the equation of state of nuclear matter. 相似文献
144.
145.
H.A. Michelsen F. Liu B.F. Kock H. Bladh A. Boiarciuc M. Charwath T. Dreier R. Hadef M. Hofmann J. Reimann S. Will P.-E. Bengtsson H. Bockhorn F. Foucher K.-P. Geigle C. Mounaïm-Rousselle C. Schulz R. Stirn B. Tribalet R. Suntz 《Applied physics. B, Lasers and optics》2007,87(3):503-521
We have performed a comparison of ten models that predict the temporal behavior of laser-induced incandescence (LII) of soot.
In this paper we present a summary of the models and comparisons of calculated temperatures, diameters, signals, and energy-balance
terms. The models were run assuming laser heating at 532 nm at fluences of 0.05 and 0.70 J/cm2 with a laser temporal profile provided. Calculations were performed for a single primary particle with a diameter of 30 nm
at an ambient temperature of 1800 K and a pressure of 1 bar. Preliminary calculations were performed with a fully constrained
model. The comparison of unconstrained models demonstrates a wide spread in calculated LII signals. Many of the differences
can be attributed to the values of a few important parameters, such as the refractive-index function E(m) and thermal and
mass accommodation coefficients. Constraining these parameters brings most of the models into much better agreement with each
other, particularly for the low-fluence case. Agreement among models is not as good for the high-fluence case, even when selected
parameters are constrained. The reason for greater variability in model results at high fluence appears to be related to solution
approaches to mass and heat loss by sublimation.
PACS 65.80.+n; 78.20.Nv; 42.62.-b; 44.05.+e 相似文献
146.
R. Boutami M. J.G. Borge H. Mach L. M. Fraile K. Gulda A. J. Aas L. M. García-Raffi E. Hagebø W. Kurcewicz G. Løvhøiden T. Martínez B. Rubio J. L. Taín O. Tengblad 《The European physical journal. Special topics》2007,150(1):87-88
There is lack of knowledge of the structure of the 231Ac
nucleus located in the upper border of the
island of octupole deformation centered around A = 225.
We have populated the excited states in 231Ac by beta-decay from the parent 231Ra
produced at ISOLDE, CERN.
The low-energy structure of 231Ac has been investigated by
means of γ, conversion electrons, γ-γ and γ-e-
spectroscopy. We report here in the precise
determination in 231Ac of the half-life of the most intensively populated states
by the Advanced Time Delayed ββγ(t) technique. 相似文献
147.
A new 8X beam condenser has been designed by the Beckman Instruments, Inc., for use with the supersize IR-11 and IR-12. This letter will report on results obtained with this accessory. 相似文献
148.
149.
150.
Bis‐benzimidazolium salts were prepared successfully from commercially available and inexpensive o‐phenylenediamine through a series of simple reactions. The bis‐NHC‐Pd complexes prepared in situ can catalyze Suzuki‐Miyaura cross‐coupling reaction under very mild conditions in aqueous media with excellent yields. The efficiency of this reaction is demonstrated by its compatibility with a range of functional groups. Di‐ortho‐substituted biaryls could be accomplished in 89–99% yields. Moreover, the rigorous exclusion of air or moisture is not required in these transformations. 相似文献