209 research outputs found
Effect of photoions on the line shapes of the F\"orster resonance and microwave transitions in cold rubidium Rydberg atoms
Experiments on the spectroscopy of the F\"orster resonance Rb(37P)+Rb(37P) ->
Rb(37S)+Rb(38S) and microwave transitions nP -> n'S, n'D between Rydberg states
of cold Rb atoms in a magneto-optical trap have been performed. Under ordinary
conditions, all spectra exhibited a 2-3 MHz line width independently of the
interaction time of atoms with each other or with microwave radiation, although
the ultimate resonance width should be defined by the inverse interaction time.
Analysis of the experimental conditions has shown that the main source of the
line broadening was the inhomogeneous electric field of cold photoions appeared
at the excitation of initial Rydberg nP states by broadband pulsed laser
radiation. Using an additional pulse of the electric field, which rapidly
removed the photoions after the laser pulse, lead to a substantial narrowing of
the microwave and F\"orster resonances. An analysis of various sources of the
line broadening in cold Rydberg atoms has been conducted.Comment: 10 pages, 6 figure
Isolation of Peaks in TDS Spectra of Deuterium from Ion Irradiated Tungsten
AbstractInteraction of deuterium with radiation defects in tungsten was studied by means of thermal desorption spectroscopy. The displacement damage in a recrystallized tungsten foil was produced by irradiation with 10 keV/D ions to the fluences in the range of 3–8×1019 D/m2 at room temperature. The resulted thermal desorption spectra consisted of three wide overlapping peaks. It was shown that annealing of the damaged sample at 550 K and subsequent implantation with 0.67 keV/D ions allows to isolate the peak corresponding to deuterium release from vacancies
Effect of finite detection efficiency on the observation of the dipole-dipole interaction of a few Rydberg atoms
We have developed a simple analytical model describing multi-atom signals
that are measured in experiments on dipole-dipole interaction at resonant
collisions of a few Rydberg atoms. It has been shown that finite efficiency of
the selective field-ionization detector leads to the mixing up of the spectra
of resonant collisions registered for various numbers of Rydberg atoms. The
formulas which help to estimate an appropriate mean Rydberg atom number for a
given detection efficiency are presented. We have found that a measurement of
the relation between the amplitudes of collisional resonances observed in the
one- and two-atom signals provides a straightforward determination of the
absolute detection efficiency and mean Rydberg atom number. We also performed a
testing experiment on resonant collisions in a small excitation volume of a
sodium atomic beam. The resonances observed for 1 to 4 detected Rydberg atoms
have been analyzed and compared with theory.Comment: 10 pages, 4 figures; equations 8,9,18,19,23,26-31, figures 3 and
4(d), and measurements revised in version
Deterministic single-atom excitation via adiabatic passage and Rydberg blockade
We propose to use adiabatic rapid passage with a chirped laser pulse in the
strong dipole blockade regime to deterministically excite only one Rydberg atom
from randomly loaded optical dipole traps or optical lattices. The chirped
laser excitation is shown to be insensitive to the random number \textit{N} of
the atoms in the traps. Our method overcomes the problem of the
dependence of the collective Rabi frequency, which was the main obstacle for
deterministic single-atom excitation in the ensembles with unknown \textit{N},
and can be applied for single-atom loading of dipole traps and optical
lattices.Comment: 6 pages, 5 figures. Version 5 is expanded and submitted to PRA. Typo
in Fig.4 corrected in Version 2. Version 3 and 4 are duplicates of V
Ionization of Sodium and Rubidium nS, nP and nD Rydberg atoms by blackbody radiation
Results of theoretical calculations of ionization rates of Rb and Na Rydberg
atoms by blackbody radiation (BBR) are presented. Calculations have been
performed for nS, nP and nD states of Na and Rb, which are commonly used in a
variety of experiments, at principal quantum numbers n=8-65 and at three
ambient temperatures of 77, 300 and 600 K. A peculiarity of our calculations is
that we take into account the contributions of BBR-induced redistribution of
population between Rydberg states prior to photoionization and field ionization
by extraction electric field pulses. The obtained results show that these
phenomena affect both the magnitude of measured ionization rates and shapes of
their dependencies on n. The calculated ionization rates are compared with the
results of our earlier measurements of BBR-induced ionization rates of Na nS
and nD Rydberg states with n=8-20 at 300 K. A good agreement for all states
except nS with n>15 is observed. We also present the useful analytical formulae
for quick estimation of BBR ionization rates of Rydberg atoms.Comment: 14 pages, 6 figures, 6 tables in Appendi
Ionization of Rydberg atoms by blackbody radiation
We have studied an ionization of alkali-metal Rydberg atoms by blackbody
radiation (BBR). The results of the theoretical calculations of ionization
rates of Li, Na, K, Rb and Cs Rydberg atoms are presented. Calculations have
been performed for nS, nP and nD states which are commonly used in a variety of
experiments, at principal quantum numbers n=8-65 and at the three ambient
temperatures of 77, 300 and 600 K. A peculiarity of our calculations is that we
take into account the contributions of BBR-induced redistribution of population
between Rydberg states prior to photoionization and field ionization by
extraction electric field pulses. The obtained results show that these
phenomena affect both the magnitude of measured ionization rates and shapes of
their dependences on n. A Cooper minimum for BBR-induced transitions between
bound Rydberg states of Li has been found. The calculated ionization rates are
compared with our earlier measurements of BBR-induced ionization rates of Na nS
and nD Rydberg states with n=8-20 at 300 K. A good agreement for all states
except nS with n>15 is observed. Useful analytical formulas for quick
estimation of BBR ionization rates of Rydberg atoms are presented. Application
of BBR-induced ionization signal to measurements of collisional ionization
rates is demonstrated.Comment: 36 pages, 16 figures. Paper is revised following NJP referees'
comments and suggestion
Assessment of the psychophysiological and functional state of basketball students in the pre-competition period
Objective: to assess the psychophysiological and functional state of the body of basketball students in the pre-competition period.Materials and methods: the study involved female basketball students with a sports category (girls, n = 18) in the pre-competition period. The article presents an analysis of the results of the psychophysiological and functional state of the body of the examined, obtained through the use of complex control using psychodiagnostic and functional research methods.Results: indicators of psychodiagnostic techniques characterize the insufficient development of the studied properties of attention for those engaged in playing sports and the fitness of the functional abilities of the leading hand of basketball players. The revealed data of the tapping test correspond to the criterion of the lower limit of optimal performance, which causes insufficient physical readiness for competitive activity. The obtained results of temporal and spectral indicators of heart rate variability were not typical for students engaged in playing sports, which causes an increase in the degree of tension of regulatory systems and characterizes the development of fatigue in the pre-competition period of the surveyed athletes. The use of the spirometric method determined the discrepancy between the results obtained and the proper values characteristic of the weight and height parameters of the subjects, which indicates violations of the ventilatory function of the lungs and reduced respiratory musculature capabilities of basketball students.Conclusion: the analysis of the obtained data on the psychophysiological and functional state of the body of basketball students in the pre-competition period determines the need to build a training process with the inclusion of psychological and pedagogical training aimed at expanding the physiological reserves of functional systems, improving the psychomotor properties of the body that determine the success of competitive activity and increasing the share of training effects aimed at improving the quality of strength endurance
Optical spectroscopy of complex open 4-shell ions Sn-Sn
We analyze the complex level structure of ions with many-valence-electron
open [Kr] 4 sub-shells (=7-4) with ab initio
calculations based on configuration-interaction many-body perturbation theory
(CI+MBPT). Charge-state-resolved optical and extreme ultraviolet (EUV) spectra
of Sn-Sn ions were obtained using an electron beam ion trap.
Semi-empirical spectral fits carried out with the orthogonal parameters
technique and Cowan code calculations lead to 90 identifications of
magnetic-dipole transitions and the determination of 79 energy
ground-configuration levels, questioning some earlier EUV-line assignments. Our
results, the most complete data set available to date for these ground
configurations, confirm the ab initio predictive power of CI+MBPT calculations
for the these complex electronic systems.Comment: 18 pages, 5 figure
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