3,498 research outputs found
Electric Deflection of Rotating Molecules
We provide a theory of the deflection of polar and non-polar rotating
molecules by inhomogeneous static electric field. Rainbow-like features in the
angular distribution of the scattered molecules are analyzed in detail.
Furthermore, we demonstrate that one may efficiently control the deflection
process with the help of short and strong femtosecond laser pulses. In
particular the deflection process may by turned-off by a proper excitation, and
the angular dispersion of the deflected molecules can be substantially reduced.
We study the problem both classically and quantum mechanically, taking into
account the effects of strong deflecting field on the molecular rotations. In
both treatments we arrive at the same conclusions. The suggested control scheme
paves the way for many applications involving molecular focusing, guiding, and
trapping by inhomogeneous fields
An automated method for the determination of deoxyribonuclease activity as exemplified by fractionation of the components of the medicament VaridaseÂź
The activity of most deoxyribonuclease enzymes can be monitored by measuring the change in absorbance at 260 nm which accompanies the breakdown of the double-stranded structure of native DNA. An automated method for determining deoxyribonuclease activity, based on such an absorbance change, which can overcome problems of inhibition arising from the presence of inorganic cations, is described. Variations in inorganic cation concentration is a particular problem when measuring the activity of chromatographic fractions eluted via a salt gradient. A comparison is made between the automated and a manual method for the assay of deoxyribonuclease active constituents, of the medicament âVaridaseâ, eluted from a Cellex-D (Bio-Rad Laboratories Ltd) anionic exchange resin using a 0.05-1.0 M sodium chloride gradient
Constraints on T-Odd, P-Even Interactions from Electric Dipole Moments
We construct the relationship between nonrenormalizable,effective,
time-reversal violating (TV) parity-conserving (PC) interactions of quarks and
gauge bosons and various low-energy TVPC and TV parity-violating (PV)
observables. Using effective field theory methods, we delineate the scenarious
under which experimental limits on permanent electric dipole moments (EDM's) of
the electron, neutron, and neutral atoms as well as limits on TVPC observables
provide the most stringent bounds on new TVPC interactions. Under scenarios in
which parity invariance is restored at short distances, the one-loop EDM of
elementary fermions generate the most severe constraints. The limits derived
from the atomic EDM of Hg are considerably weaker. When parity symmetry
remains broken at short distances, direct TVPC search limits provide the least
ambiguous bounds. The direct limits follow from TVPC interactions between two
quarks.Comment: 43 pages, 9 figure
P and T Violation From Certain Dimension Eight Weinberg Operators
Dimension eight operators of the Weinberg type have been shown to give
important contributions to CP violating phenomena, such as the electric dipole
moment of the neutron. In this note we show how operators related to these (and
expected to occur on equal footing) can give rise to time-reversal violating
phenomena such as atomic electric dipole moments. We also estimate the induced
parity violating phenomena such as small ``wrong'' parity admixtures in atomic
states and find that they are negligible. Uses harvmac.tex and epsf.tex; one
figure submitted as a uuencoded, compressed EPS file.Comment: 6 pages, EFI-92-5
The first close-up of the "flip-flop" phenomenon in a single star
We present temperature maps of the active late-type giant FK Com which
exhibit the first imagining record of the ``flip-flop'' phenomenon in a single
star. The phenomenon, in which the main part of the spot activity shifts 180
degrees in longitude, discovered a decade ago in FK Com, was reported later
also in a number of RS CVn binaries and a single young dwarf. With the surface
images obtained right before and after the ``flip-flop'', we clearly show that
the ``flip-flop'' phenomenon in FK Com is caused by changing the relative
strengths of the spot groups at the two active longitudes, with no actual spot
movements across the stellar surface, i.e. exactly as it happens in other
active stars.Comment: 4 pages, accepted by A&A Letter
Hadronic effects in leptonic systems: muonium hyperfine structure and anomalous magnetic moment of muon
Contributions of hadronic effects to the muonium physics and anomalous
magnetic moment of muon are considered. Special attention is paid to
higher-order effects and the uncertainty related to the hadronic contribution
to the hyperfine structure interval in the ground state of muonium.Comment: Presented at PSAS 2002 (St. Petersburg
Testing Bell's inequality with two-level atoms via population spectroscopy
We propose a feasible experimental scheme, employing methods of population
spectroscopy with two-level atoms, for a test of Bell's inequality for massive
particles. The correlation function measured in this scheme is the joint atomic
function. An inequality imposed by local realism is violated by any
entangled state of a pair of atoms.Comment: 4 pages, REVTeX, no figures. More info on
http://www.ligo.caltech.edu/~cbrif/science.htm
Collisional perturbation of radio-frequency E1 transitions in an atomic beam of dysprosium
We have studied collisional perturbations of radio-frequency (rf)
electric-dipole (E1) transitions between the nearly degenerate opposite-parity
levels in atomic dysprosium (Dy) in the presence of 10 to 80 Torr of
H, N, He, Ar, Ne, Kr, and Xe. Collisional broadening and
shift of the resonance, as well as the attenuation of the signal amplitude are
observed to be proportional to the foreign-gas density with the exception of
H and Ne, for which no shifts were observed. Corresponding rates and cross
sections are presented. In addition, rates and cross sections for O are
extracted from measurements using air as foreign gas. The primary motivation
for this study is the need for accurate determination of the shift rates, which
are needed in a laboratory search for the temporal variation of the
fine-structure constant [A. T. Nguyen, D. Budker, S. K. Lamoreaux, and J. R.
Torgerson, Phys. Rev. A \textbf{69}, 22105 (2004)].Comment: 11 pages, 8 figure
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