Buffer gas

About: Buffer gas is a research topic. Over the lifetime, 3565 publications have been published within this topic receiving 47283 citations.

Nuclear Polarization in He 3 Gas Induced by Optical Pumping and Dipolar Exchange

Abstract: The Overhauser nuclear polarization effect involving dipolar interactions between an optically polarized atom and the nucleus of a suitable buffer gas was observed in He/sup 3/ gas used as the buffer for the optical pumping of rubidium vapor. The rubidium was polarized and the degree of nuclear polarization of He/sup 3/ was determined. The polarization was reduced by relaxation processes. The relaxation time was proportional to the density and doubled in going from 300 to 77 deg K. (M.C.G.)

High-resolution ion mobility measurements

Abstract: Gas phase ion mobility measurements can resolve structural isomers for polyatomic ions and provide information about their geometries. A new experimental apparatus for performing high-resolution ion mobility measurements is described. The apparatus consists of a pulsed laser vaporization/desorption source coupled through an ion gate to a 63-cm-long drift tube. The ion gate is a critical component that prevents the diffusion of neutral species from the source into the drift tube. Ions travel along the drift tube under the influence of a uniform electric field. At the end of the drift tube some of the ions exit through a small aperture. They are focused into a quadrupole mass spectrometer, where they are mass analyzed, and then detected by an off-axis collision dynode and by dual microchannel plates. The apparatus is operated with a drift voltage of up to 14 000 V and a helium buffer gas pressure of around 500 Torr. The resolving power for ion mobility measurements is over an order of magnitude higher than has been achieved using conventional injected-ion drift tube techniques. Examples of the application of the new apparatus in resolving isomers of laser desorbed metallofullerenes, in studying silicon clusters generated by laser vaporization, and in following the isomerization of small nanocrystalline (NaCl)nCl− clusters as a function of temperature, are presented.

Method for reducing the inert gas fraction in methane-containing gaseous mixtures obtained from underground formations

Abstract: A method for reducing the inert gas fraction volume percent present in a methane-containing mixture produced by injecting an inert gas into a solid carbonaceous subterranean formation is disclosed. The method reduces the inert gas fraction by suspending the injection of the inert gas or by reducing a rate of injection of the inert gas. Additional methods are disclosed in which the inert gas volume percent of a gaseous mixture produced from more than one well can be maintained below the inert gas volume percent present in a gas obtained from at least one of the wells.

The Buffer Gas Beam: An Intense, Cold, and Slow Source for Atoms and Molecules

Abstract: Beams of atoms and molecules are stalwart tools for spectroscopy and studies of collisional processes. The supersonic expansion technique can create cold beams of many species of atoms and molecules. However, the resulting beam is typically moving at a speed of 300-600 m/s in the lab frame, and for a large class of species has insufficient flux (i.e. brightness) for important applications. In contrast, buffer gas beams can be a superior method in many cases, producing cold and relatively slow molecules in the lab frame with high brightness and great versatility. There are basic differences between supersonic and buffer gas cooled beams regarding particular technological advantages and constraints. At present, it is clear that not all of the possible variations on the buffer gas method have been studied. In this review, we will present a survey of the current state of the art in buffer gas beams, and explore some of the possible future directions that these new methods might take.

The High-Pressure Sodium Lamp

Abstract: Introduction - General Considerations Concerning Power Balance and Spectrum - Spectrum and Related Discharge Properties - Power Balance and Related Discharge Properties - Influence of a Buffer Gas on Discharge Properties - Ignition and Stabilisation - High-Frequency and Pulse Operation - Discharge-Tube Material and Ceramic-to-Metal Seal - Electrodes - Lamp Design - References