2,473 research outputs found
Formation of hydrogen peroxide and water from the reaction of cold hydrogen atoms with solid oxygen at 10K
The reactions of cold H atoms with solid O2 molecules were investigated at 10
K. The formation of H2O2 and H2O has been confirmed by in-situ infrared
spectroscopy. We found that the reaction proceeds very efficiently and obtained
the effective reaction rates. This is the first clear experimental evidence of
the formation of water molecules under conditions mimicking those found in cold
interstellar molecular clouds. Based on the experimental results, we discuss
the reaction mechanism and astrophysical implications.Comment: 12 pages, 3 Postscript figures, use package amsmath, amssymb,
graphic
Measurements of rotational transform due to noninductive toroidal current using motional Stark effect spectroscopy in the Large Helical Device
The change of rotational transform due to noninductive plasma current driven by a negative neutral beam, which has a value typically less than 10% of total rotational transform determined by the external current in the helical coils, is measured in the Large Helical Device with motional Stark effect spectroscopy. Radial profiles of rotational transform are derived from the radial profiles of the polarization angle of the sigma component in the Halpha line emitted from the high energy hydrogen atom of the beam with four sets of linear polarizers, spectrometers, and CCD detectors. The radial profile of the change in the rotational transform due to the noninductive toroidal current driven by the neutral beam is measured
Phase Diagram of Coupled Ladders
The 2-leg t-J ladder forms a spin liquid at half-filling which evolves to a
Luther-Emery liquid upon doping. Our aim is to obtain a complete phase diagram
for isotropic coupling (i.e. rungs and legs equal) as a function of electron
density n and the ratio J/t (>0). Two known limiting cases are: n<1/2 which is
a single band Luttinger liquid and small hole doping for J/t close to 0 which
is a Nagaoka ferromagnet. Using Lanczos techniques we examine the region
between the Nagaoka and Luther-Emery phases for 1>n>1/2. We find evidences for
gapless behavior in both spin and charge channels for J/t<0.3 consistent with
Luttinger liquids in both bonding and anti-bonding bands (i.e., C2S2). This
proposal is based on the behavior of spin and charge correlation functions. For
example the hole-hole correlation function which displays hole pairing at
larger J/t, shows hole-hole repulsion in this region. As a further test, we
examined the dependence of the energy on a relative phase shift between bonding
and antibonding bands. For J/t < 0.3 this is very weak, indicating a lack of
pairing between these channels.Comment: 21 pages, 18 figure
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