Helium nitrogen

This powerful drying agent is suitable for use with hydrogen, argon, helium, nitrogen, hydrocarbons, chlorinated hydrocarbons, esters and higher alcohols. 

Gas plasma treatment operates at low pressure and relatively low temperature. While the corona treatment is applicable to substrates in sheet or film form, the gas plasma process can treat objects of virtually any shape. The gases most widely used to generate plasma by free-radical reactions include air, argon, helium, nitrogen, and oxygen. All these, with the exception of oxygen. 

In most cases, ion activation in the reaction region or fragmentation zone is applied to increase the internal energy of the ions transmitted from the ion source. The most common means of ion activation in tandem mass spectrometry is collision-induced dissociation. CID uses gas-phase collisions between the ion and neutral target gas (such as helium, nitrogen or argon) to cause internal excitation of the ion and subsequent dissociation... 

On completion of the reaction after 10 to 14 hours, the reaction tube is removed from the furnace. The bromine may be frozen at liquid-nitrogen temperature in either bulb A or F, and both A and F are removed by sealing with the hand torch near the bulb E. The remainder of the reaction tube is transferred to the dry-box under an inert atmosphere (helium, nitrogen, or argon) and opened by breaking at the constrictions between bulbs B and E. 

Common GC mobile phases (see Table 13.2) are hydrogen, argon, helium, nitrogen, and air. Helium and nitrogen are the most commonly used. Because gas chromatographic detectors are extremely sensitive and it is desirable to keep the noise level as low as possible, it is always advisable to use very high-purity gas as the mobile phase. 

What would be the most effective diluent to a detonable mixture to lower, or prevent, detonation possibility carbon dioxide, helium, nitrogen, or argon Order the expected effectiveness. 

The molar fraction ratio between helium and nitrogen in the flue gas was determined from gas chromatographic measurements. The molar flow of the tracer gas of helium was measured. Because Rogers applied batch methods to measure water vapour in flue gas and the helium-nitrogen ratio, the overall method become a semi-continuous method. The water vapour of the flue gas was measured batchwise by freezing it out in an U-tube placed in an acetone-dry ice mixture. 

Fio. 30. Evaporation rate data obtained by Davis and Ray (1978) for dibutyl sebacate evaporating in helium, nitrogen, and carbon dioxide at 293 K. Reprinted with permission from J. Aerosol Sci. 9, 411-412, Davis, E. J., and Ray, A. K., Copyright 1978, Pergamon Press pic. 

The mobile phase in vapour phase chromatography is a gas (e.g. hydrogen, helium, nitrogen or argon) and the stationary phase is a non-volatile liquid impregnated onto a porous material. The mixture to be purified is injected into a heated inlet whereby it is vaporised and taken into the column by the carrier gas. It is separated into its components by partition between the liquid on the porous support and the gas. For this reason vapour-phase chromatography is sometimes referred to as gas-liquid chromatography. 

The essential components of a gas chromatography system are shown in Figure 3.4. The mobile phase (called the carrier gas) is inert, usually helium, nitrogen, or argon. The gas is directed past an injection port, the entry point of the sample. The sample, dissolved in a solvent, is injected with a syringe through a rubber septum into the injection port. The column, injection port, and detector are in individual ovens maintained at elevated temperatures so that the sample components remain vaporized throughout their residence time in the system. 

Volatile compounds can be separated in a gas chromatograph, in which the mobile phase is usually a relatively unreactive gas such as helium, nitrogen, or hydrogen. The principles are the same as those for liquid chromatography, but the output is more often a chromatogram, rather than a series of eluted samples (Fig. 3). The chromatogram shows when each solute... 

Although the proposed mechanism is consistent for photolysis of iodine in helium, nitrogen and methane (24), substantive deviations were present at low densities and especially near the critical point of ethane. As Figure 3 shows, the quantum yields at these low densities are consistently below one, the value expected in this high diffusivity regime where kd k i. 

This method is based on the fact that molecular association may lead to an efficient chiral recognition leading to enantiomeric separation when a chiral stationary phase (e.g. cyclodextrins) is used in GC. The gas (mobile phase, e.g. hydrogen, helium, nitrogen) is carrying the chiral analyte through the stationary phase. The enantiomers to be analyzed... 

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