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Buffer gas
About: Buffer gas is a research topic. Over the lifetime, 3565 publications have been published within this topic receiving 47283 citations.
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TL;DR: Three regimes characterized by the respective analytic form of the ion's equilibrium energy distribution are found and final ion temperatures down to the millikelvin regime can be achieved by adiabatically decreasing the spatial extension of the buffer gas and the effective ion trap depth (forced sympathetic cooling).
Abstract: We theoretically investigate the dynamics of a trapped ion immersed in a spatially localized buffer gas. For a homogeneous buffer gas, the ion's energy distribution reaches a stable equilibrium only if the mass of the buffer gas atoms is below a critical value. This limitation can be overcome by using multipole traps in combination with a spatially confined buffer gas. Using a generalized model for elastic collisions of the ion with the buffer-gas atoms, the ion's energy distribution is numerically determined for arbitrary buffer-gas distributions and trap parameters. Three regimes characterized by the respective analytic form of the ion's equilibrium energy distribution are found. Final ion temperatures down to the millikelvin regime can be achieved by adiabatically decreasing the spatial extension of the buffer gas and the effective ion trap depth (forced sympathetic cooling).
50 citations
TL;DR: In this article, an easy and low-cost approach to synthesize single-walled carbon nanotubes (SWCNTs) by direct current arc discharge in low-pressure air with Ni/Y as catalysts was demonstrated.
50 citations
TL;DR: In this paper, the recombination of spectroscopically identified H3+ ions with thermal electrons has been studied in pulsed afterglow plasma by means of an infrared cavity ring-down spectrometer (CRDS).
50 citations
TL;DR: In this article, a detailed comparison of the performance of the three detection methods, namely, fluorescence, photoionization, and deflection, is made, from the point of view of the sources of background and ways of discriminating against it, detection selectivity and absolute sensitivity.
Abstract: This review deals with the problem of selective detection of single atoms by laser radiaton. It begins with a classification of the detection methods (fluorescence, photoionization, deflection), discusses detection conditions (atomic vapor, atomic beam, buffer gas), and gives estimates of the parameters of laser radiation ensuring effective detection. Next, a detailed comparision is made of each of the detection methods. It is shown that in the fluorescence method the maximum efficiency of the detection process is achieved for cyclic interaction of atoms with laser radiation. In the photoionization method the most suitable technique is multistage photoionization of atoms by laser radiation. The highest ionization selectivity and a high efficiency are obtained by multistage excitation of an atom either to a Rydberg state followed by ionization with an electric field pulse or to a narrow autoionizing state with a large excitation cross section. Both these techniques are considered from the point of view of the sources of background and ways of discriminating against it, detection selectivity, and absolute sensitivity; the experimental results are analyzed. In discussing the deflection method consideration is given to deflection of an atom in a magnetic field after excitation with laser radiation and to deflection of atoms by resonant optical pressure. The review concludes with a brief discussion of the prospective applications of these detection methods in nuclear physics, atomic physics, and chemistry.
50 citations
TL;DR: The creation of a Bose-Einstein condensate using buffer-gas cooling is reported, the first realization of BOSE-E Einstein condensation using a broadly general method which relies neither on laser cooling nor unique atom-surface properties.
Abstract: We report the creation of a Bose-Einstein condensate using buffer-gas cooling, the first realization of Bose-Einstein condensation using a broadly general method which relies neither on laser cooling nor unique atom-surface properties. Metastable helium ((4)He*) is buffer-gas cooled, magnetically trapped, and evaporatively cooled to quantum degeneracy. 10(11) atoms are initially trapped, leading to Bose-Einstein condensation at a critical temperature of 5 microK and threshold atom number of 1.1 x 10(6). This method is applicable to a wide array of paramagnetic atoms and molecules, many of which are impractical to laser cool and impossible to surface cool.
50 citations