48,045 research outputs found
Formation of iron nitride thin films with Al and Ti additives
In this work we investigate the process of iron nitride (Fe-N) phase
formation using 2 at.% Al or 2 at.% Ti as additives. The samples were prepared
with a magnetron sputtering technique using different amount of nitrogen during
the deposition process. The nitrogen partial pressure (\pn) was varied between
0-50% (rest Argon) and the targets of pure Fe, [Fe+Ti] and [Fe+Al] were
sputtered. The addition of small amount of Ti or Al results in improved
soft-magnetic properties when sputtered using \pn 10\p. When \pn is
increased to 50\p non-magnetic Fe-N phases are formed. We found that iron
mononitride (FeN) phases (N at% 50) are formed with Al or Ti addition at
\pn =50% whereas in absence of such addition \eFeN phases (N\pat30) are
formed. It was found that the overall nitrogen content can be increased
significantly with Al or Ti additions. On the basis of obtained result we
propose a mechanism describing formation of Fe-N phases Al and Ti additives.Comment: 9 Pages, 7 Figure
Comparison of Canonical and Grand Canonical Models for selected multifragmentation data
Calculations for a set of nuclear multifragmentation data are made using a
Canonical and a Grand Canonical Model. The physics assumptions are identical
but the Canonical Model has an exact number of particles, whereas, the Grand
Canonical Model has a varying number of particles, hence, is less exact.
Interesting differences are found.Comment: 12 pages, Revtex, and 3 postscript figure
One-parameter scaling theory for DNA extension in a nanochannel
Experiments measuring DNA extension in nanochannels are at odds with even the
most basic predictions of current scaling arguments for the conformations of
confined semiflexible polymers such as DNA. We show that a theory based on a
weakly self-avoiding, one-dimensional "telegraph" process collapses
experimental data and simulation results onto a single master curve throughout
the experimentally relevant region of parameter space and explains the
mechanisms at play.Comment: Revised version. 5 pages, 4 figures, revised version, supplementary
informatio
Contrast Interferometry Using Bose-Einstein Condensates to Measure h/m and the Fine Structure Constant
The kinetic energy of an atom recoiling due to absorption of a photon was
measured as a frequency using an interferometric technique called ``contrast
interferometry''. Optical standing wave pulses were used as atom-optical
elements to create a symmetric three-path interferometer with a Bose-Einstein
condensate. The recoil phase accumulated in different paths was measured using
a single-shot detection technique. The scheme allows for additional photon
recoils within the interferometer and its symmetry suppresses several random
and systematic errors including those from vibrations and ac Stark shifts. We
have measured the photon recoil frequency of sodium to ppm precision, using
a simple realization of this scheme. Plausible extensions should yield a
sufficient precision to bring within reach a ppb-level determination of
and the fine structure constant
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