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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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Abstract: Direct loading of lanthanide atoms into magneto-optical traps (MOTs) from a very slow cryogenic buffer gas beam source is achieved, without the need for laser slowing. The beam source has an average forward velocity of 60– and a velocity half-width of , which allows for direct MOT loading of Yb, Tm, Er and Ho. Residual helium background gas originating from the beam results in a maximum trap lifetime of about 80 ms (with Yb). The addition of a single-frequency slowing laser applied to the Yb in the buffer gas beam increases the number of trapped Yb atoms to with a loading rate of . Decay to metastable states is observed for all trapped species and decay rates are measured. Extension of this approach to the loading of molecules into a MOT is discussed.
29 citations
Patent•
23 Sep 1994
TL;DR: In this article, the authors describe a process for forming a thin film by chemical vapor deposition which comprises repeating a substrate processing step on one or more substrates placed inside a reaction chamber by introducing a reaction gas inside the reaction chamber.
Abstract: A process for forming a thin film by chemical vapor deposition which comprises repeating a substrate processing step on one or more substrates placed inside a reaction chamber by introducing a reaction gas inside the reaction chamber. The process includes a step of introducing a passivation gas or the like for passivating the surface of a thin film deposited on the fixing jig or other peripheral members between substrate processing steps. The passivation gas is, for example, an adsorbent gas or an oxidizing gas. More specifically, an example of an adsorbent gas is a mixture of an inert gas and from 0.1 to 10% of NH3 gas or SiH2 Cl2 gas, and an example of an oxidizing gas is a mixture of an inert gas and at least one selected from the group of oxygen, nitrogen, monoxide, and nitrogen dioxide. The inert gas may also be replaced with N2 gas.
29 citations
TL;DR: Germanium nanocrystals with sizes ranging from 1 to 5 nm are found to depend on the buffer gas, with helium yielding a narrower size distribution than argon and argon exhibiting a stronger pressure dependence of the produced particle sizes.
Abstract: Germanium nanocrystals with sizes ranging from 1 to 5 nm are condensed out of the gas phase in helium or argon buffer-gas atmospheres and subsequently deposited. The generated particle sizes are found to depend on the buffer gas, with helium yielding a narrower size distribution than argon and argon exhibiting a stronger pressure dependence of the produced particle sizes. Structural analysis of nanoparticles with average sizes around 5 nm reveals the bulklike cubic (diamond) phase—in contrast to recent experiments which suggest the tetragonal phase for similar-sized particles. These results are explained in terms of particle formation dynamics.
29 citations
TL;DR: A heat-pipe apparatus allowing for the additive coloration of laser-quality alkali halide crystals is described, which allows the same charge of alkali metal to be used many times over.
Abstract: A heat‐pipe apparatus allowing for the additive coloration of laser‐quality alkali halide crystals is described. It has the following features: (1) Prepolished crystals emerge ready for direct installation in the laser; (2) F‐center densities are directly proportional to the buffer gas pressure; (3) An air lock allows the same charge of alkali metal to be used many times over.
29 citations
TL;DR: A shock tube that features a sliding gate valve in order to mechanically constrain the reactive test gas mixture to an area close to the shock tube endwall, separating it from a specially formulated non-reactive buffer gas mixture is developed.
Abstract: We have developed a shock tube that features a sliding gate valve in order to mechanically constrain the reactive test gas mixture to an area close to the shock tube endwall, separating it from a specially formulated non-reactive buffer gas mixture. This second-generation Constrained Reaction Volume (CRV) strategy enables near-constant-pressure shock tube test conditions for reactive experiments behind reflected shocks, thereby enabling improved modeling of the reactive flow field. Here we provide details of the design and operation of the new shock tube. In addition, we detail special buffer gas tailoring procedures, analyze the buffer/test gas interactions that occur on gate valve opening, and outline the size range of fuels that can be studied using the CRV technique in this facility. Finally, we present example low-temperature ignition delay time data to illustrate the CRV shock tube's performance.
29 citations