4,699 research outputs found
Optical stark effect in the 2-photon spectrum of NO
A large optical Stark effect has been observed in the two-photon spectrum X(2)Pi yields A(2)Sigma(+)_ in NO. It is explained as a near-resonant process in which the upper state of the two-photon transition is perturbed by interactions with higher-lying electronic states coupled by the laser field. A theoretical analysis is presented along with coupling parameters determined from ab initio wave functions. The synthetic spectrum reproduces the major experimental features
Properties of Vacuum Arc Influenced by Electrode Diameter and Material in TMF Contact Based on Forced Current Zero
With the increase in electrical equipment in More/All Electric Aircraft, 270 V dc power supply systems will be needed. One method for DC interruption is forced current zero (FCZ). Based on FCZ technology with transverse-magnetic-field (TMF) contact, the spiral-type contacts are designed. Experiments with different currents are carried out with contact diameters being 30 mm, 40 mm, and 50 mm, and arcing surface materials Cu-W80 alloy and Cu-Cr50 alloy respectively. It is indicated by the experimental results that breaking capacity of vacuum interrupter and vacuum arc appearance are closely related to the electrode diameter and material. For the same size of electrode diameter, the breaking capacity in Cu-Cr50 is better than that in Cu-W80. With increasing electrode diameter, arc column expansion velocity and diameter increase gradually. Breaking capacity is increasing with larger contact diameter
A different view of the quantum Hall plateau-to-plateau transitions
We demonstrate experimentally that the transitions between adjacent integer
quantum Hall (QH) states are equivalent to a QH-to-insulator transition
occurring in the top Landau level, in the presence of an inert background of
the other completely filled Landau levels, each contributing a single unit of
quantum conductance, , to the total Hall conductance of the system.Comment: 10 pages, 4 figures, Revtex 3.
HST and LAMOST discover a dual active galactic nucleus in J0038+4128
We report the discovery of a kiloparsec-scale dual active galactic nucleus
(AGN) in J0038+4128. From the Hubble Space Telescope (HST) Wide Field Planetary
Camera (WFPC2) images, we find two optical nuclei with a projection separation
of 4.7 kpc (3.44 arcsec). The southern component (J0038+4128S) is
spectroscopically observed with the HST Goddard High Resolution Spectrograph in
the UV range and is found to be a Seyfert 1 galaxy with a broad Ly alpha
emission line. The northern component (J0038+4128N) is spectroscopically
observed during the Large Sky Area Multi-Object Fibre Spectroscopic Telescope
(also named the Guoshoujing Telescope) pilot survey in the optical range. The
observed line ratios as well as the consistency of redshift of the nucleus
emission lines and the host galaxy's absorption lines indicate that J0038+4128N
is a Seyfert 2 galaxy with narrow lines only. These results thus confirm that
J0038+4128 is a Seyfert 1-Seyfert 2 AGN pair. The HST WFPC2 F336W/U-band image
of J0038+4128 also reveals for the first time for a dual AGN system two pairs
of bi-symmetric arms, as are expected from the numerical simulations of such
system. Being one of a few confirmed kiloparsec-scale dual AGNs exhibiting a
clear morphological structure of the host galaxies, J0038+4128 provides an
unique opportunity to study the co-evolution of the host galaxies and their
central supermassive black holes undergoing a merging process.Comment: 6 pages, 4 figures, 2 tables, Accepted for publication in MNRAS
Letter
Cross sections for excitation of the b3Σu+, a3Σg+, and c3Πu states of H2 by low-energy electrons
We used a multichannel extension of the Schwinger variational principle [K. Takatsuka and V. McKoy, Phys. Rev. A 24, 2473 (1981)] to study the cross sections for excitation of the X 1 Σg+→b 3Σu+, a 3Σg+, and c3Πu transitions in H2 by low-energy electrons. These cross sections were obtained with two open channels for each transition and for energies near threshold to 30 eV. The results for the b3Σu+ and a 3Σg+ states agree quite well with available experimental data. However, the cross sections for excitation of the c 3Πu state differ significantly from the measured values at the two energies, 20 and 30 eV, where data are available
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