4,276 research outputs found
Optical thickness of the Olympus cloud
Results are presented from a model of telescope observations that indicate a diurnal cycle exist, at least at one location, in the Martian atmosphere. By comparing calculated intensities with observed intensities of reflected sunlight, the diurnal variations in the optical thickness of the Olympus cloud that forms near the summit of Olympus Mons during summer was estimated. The results indicate that the optical depth at 0.4 microns rises sharply from near zero in late morning to about 0.8 in the early afternoon
Evidence for the singlet-dimer ground state in an S = 1 antiferromag netic bond alternating chain
Susceptibility, ESR and magnetization measurements have been performed on si
ngle crystals of an S=1 bond alternating chain compound: [Ni(333-tet)(\mu-NO
_2)](ClO_4) (333-tet = N,N'-bis(3-aminopropyl)propane-1,3-diamine) and the c
ompound doped with a small amount of Zn. We observed an anomalous angular de
pendence in the Zn-doped sample. These behaviors are well explained by the m
odel based on the VBS picture for the singlet-dimer phase. The picture impli es
that the free spins of S=1 with a positive single-ion anisotropy are indu ced
at the edges of the chains without forming the singlet-dimer.Comment: RevTeX, 14pages (preprint.sty) with 5figures, submitted to Phys. R
ev. Let
Dynamical properties of S=1 bond-alternating Heisenberg chains in transverse magnetic fields
We calculate dynamical structure factors of the S=1 bond-alternating
Heisenberg chain with a single-ion anisotropy in transverse magnetic fields,
using a continued fraction method based on the Lanczos algorithm. In the
Haldane-gap phase and the dimer phase, dynamical structure factors show
characteristic field dependence. Possible interpretations are discussed. The
numerical results are in qualitative agreement with recent results for
inelastic neutron-scattering experiments on the S=1 bond-alternating
Heisenberg-chain compound and the
S=1 Haldane-gap compound in
transverse magnetic fields.Comment: 7 pages, 6 figure
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