444 research outputs found
Future directions for beam-foil spectroscopy
The beam-foil source has proved to be so useful for the study of atomic energy levels that it is almost trivial to propose a variety of new experiments involving new elements, higher energies, a broader wavelength range, shorter time intervals, pulsed beams, different targets, and new configurations in geometry or external fields. However, what is perhaps not so trivial is to propose experiments for which there is a specific purpose, experiments from which a novel kind of information might be expected. It is from this latter point of view that the author shall talk about experiments which seem to offer unusual opportunities to learn new things about atoms
Charge of ions emitting spectral lines
Ion charge determination from emitting spectral lines using beam foil light source techniqu
Charge identification for spectral lines in nitrogen
Ion charge identification for spectral lines in nitrogen by beam foil light source techniqu
The mean lives of some excited levels in nitrogen 1
Beam foil measurements of multiplet mean lives in nitrogen deca
Beam-foil spectrum of nitrogen at ultraviolet wavelengths
Spectrum analysis on foil excited nitrogen beam during acceleration at ultraviolet wavelength
The existence of a 2Po excited state for the e+Ca system
The Configuration Interaction method is used to demonstrate that there is an
electronically stable state of positronic calcium with an orbital angular
momentum of L=1. This prediction relies on the use of an asymptotic series to
estimate the variational limit of the energy. The best estimate of the binding
energy is 37 meV. A discussion of the structure of the system is also
presented.Comment: 4 pages, 2 figures, in press PR
Femtosecond transparency in the extreme ultraviolet
Electromagnetically induced transparency-like behavior in the extreme
ultraviolet (XUV) is studied theoretically, including the effect of intense 800
nm laser dressing of He 2s2p (1Po) and 2p^2 (1Se) autoionizing states. We
present an ab initio solution of the time-dependent Schrodinger equation (TDSE)
in an LS-coupling configuration interaction basis set. The method enables a
rigorous treatment of optical field ionization of these coupled autoionizing
states into the N = 2 continuum in addition to N = 1. Our calculated transient
absorption spectra show encouraging agreement with experiment.Comment: 25 pages, 7 figures, 1 tabl
On the possibility to supercool molecular hydrogen down to superfluid transition
Recent calculations by Vorobev and Malyshenko (JETP Letters, 71, 39, 2000)
show that molecular hydrogen may stay liquid and superfluid in strong electric
fields of the order of . I demonstrate that strong local
electric fields of similar magnitude exist beneath a two-dimensional layer of
electrons localized in the image potential above the surface of solid hydrogen.
Even stronger local fields exist around charged particles (ions or electrons)
if surface or bulk of a solid hydrogen crystal is statically charged.
Measurements of the frequency shift of the photoresonance transition
in the spectrum of two-dimensional layer of electrons above positively or
negatively charged solid hydrogen surface performed in the temperature range 7
- 13.8 K support the prediction of electric field induced surface melting. The
range of surface charge density necessary to stabilize the liquid phase of
molecular hydrogen at the temperature of superfluid transition is estimated.Comment: 5 pages, 2 figure
Castaing Instability and Precessing Domains in Confined Alkali Gases
We explore analogy between two-component quantum alkali gases and
spin-polarized helium systems. Recent experiments in trapped gases are put into
the frame of the existing theory for Castaing instability in transverse channel
and formation of homogeneous precessing domains in spin-polarized systems.
Analogous effects have already been observed in spin-polarized and
mixtures systems. The threshold effect of the confining
potential on the instability is analyzed. New experimental possibilities for
observation of transverse instability in a trap are discussed.Comment: 6 RevTex pages, no figure
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