Xenon gas

Fig. 6.5. Examples of positron lifetime spectra for (a) argon and (b) xenon gases. The argon data are for a density of 6.3 amagat at 297 K. The channel width is 1.92 ns. In (a), (i) shows the raw data, (ii) shows the signal with background removed, (iii) shows the free-positron component and (iv) shows the fitted ortho-positronium component. In (b), the spectrum for xenon is for room temperature and 9.64 amagat and has a channel width of 0.109 ns. The inset shows the fast components as extracted and discussed by Wright et al. (1985).

The aluminium absorbs the radiation, heats up and transfers the heat to xenon gas contained in the cell. As the temperature of the gas varies the curvature of a flexible mirror of antimony-coated collodion, forming a part of the cell, changes. Reflection of a light beam from this mirror, which is on the outside of the Golay cell, indicates its curvature and therefore the intensity of radiation absorbed by the cell. 

Silver difluoride [7783-95-1], AgF2, is a black crystalline powder. It has been classified as a hard fluorinating agent (3) which Hberates iodine from KI solutions and o2one from dilute aqueous acid solutions on heating. It spontaneously oxidizes xenon gas to Xe(II) in anhydrous hydrogen fluoride solutions (20). 

In other applications of CT, orally administered barium sulfate or a water-soluble iodinated CM is used to opacify the GI tract. Xenon, atomic number 54, exhibits similar x-ray absorption properties to those of iodine. It rapidly diffuses across the blood brain barrier after inhalation to saturate different tissues of brain as a function of its lipid solubility. In preliminary investigations (99), xenon gas inhalation prior to brain CT has provided useful information for evaluations of local cerebral blood flow and cerebral tissue abnormalities. Xenon exhibits an anesthetic effect at high concentrations but otherwise is free of physiological effects because of its nonreactive nature. 

The interhalogen IFT can be made only by indirect routes. For example, xenon difluoride gas can react with iodine gas to produce 1FV and xenon gas. In one experiment xenon difluoride is introduced into a rigid container until a pressure of 3.6 atm is reached. Iodine vapor is then introduced until the total pressure is 7.2 atm. Reaction is then allowed to proceed at constant temperature until completion by solidifying the IF as it is produced. The final pressure in the flask due to the xenon and excess iodine vapor is 6.0 atm. (a) What is the formula of the mterhalogen (b) Write the chemical equation for its formation. 

C04-0108. Although xenon is a noble gas, it reacts with fluorine and oxygen. When xenon gas reacts with F2... 

R. W. Mair, R. Wang, M. S. Rosen, D. Candela, D. G. Cory, R. L. Walsworth 2003, (Applications of controlled-flow laser-polarized xenon gas to porous and granular media study), Magn. Reson. Imag. 21, 287. 

L. M. Schwartz, R. L. Walswofhry 2001, (Tortuosity measurement and the effects of finite pulse widths on xenon gas diffusion NMR studies of porous media), Mag. Reson. Imag. 19, 345. 

With the rare exception of xenon gas NMR of fluidized beds, which we discuss later, granular flow studies by NMR detect signals from the particles and not the surrounding medium. Because it is technically easier to obtain NMR signals from liquids rather than solids, the majority of granular NMR studies so far use solid particles containing liquids. 

Figure 5.3.5 displays dynamic NMR microscopy of xenon gas phase Poiseuille flow with an average velocity of 25 mm s-1 and self-diffusion coefficient of 4.5 mm2 s-1 at 130 kPa xenon gas pressure with numerical simulation (A) and experimental flow profiles (B-D) of xenon gas. 

Figure 5.3.8 displays a photograph of the actual combustion zone. The methane-xenon gas was mixed with air before entering the NMR detection cell in the probe head. The gas mixture was blown through an area with molecular sieve pellets (i.e.,... 

Assume that 185.00 grams of fluorine gas and 4.0 moles of xenon gas are contained in a... 

A known amount of zeolite was loaded into a 10 mm NMR tube with an attached vacuum valve. The sample was evacuated to about 2xl0 < torr for 3 days at room temperature, then it was heated to 350 C with a heating rate of 0.2 C/min, the sample was allowed to maintain at this temperature for about 30 hours (2x10 torr). After cooling to room temperature, a known amount of xenon gas was introduced into the sample tube and was sealed by the vacuum valve. All the xenon adsorption isotherms were measured by volumetric method at room temperature. 

The NMR spectra of adsorbed xenon were obtained on a Bruker MSL-300 spectrometer operating at 83.0 MHZ and 295K. Typically, 2000-40000 signal acquisitions were accumulated for each spectrum with a recycle delay of 0.3s between 90 pulses. The Xe NMR chemical shifts were referenced to that of external xenon gas extrapolated to zero pressure using Jameson s equation [11]. All resonance signals of xenon adsorbed in zeolites were shifted downfield from the reference but were taken to be positive in this report. 

Xenon cff[ F]fluoride (Xe[ F]F2) can be prepared through several approaches. The most common involves the thermal reaction between [ F]F2 and xenon gas in a sealed nickel vessel maintained at 390 °C (Scheme 6, 70% radiochemical yield) [80]. 

MS FAB technique — negative mode- Xenon gas -glycerol matrix ... 

MS FAB technique - negative mode — Xenon gas — glycerol matrix... 

In Figure 1, the effect of xenon gas is also shown. From the initial slope of the curve, the probability of crosslinking is calculated to increase by 44% in the presence of nitrous oxide at 600 mm. of Hg as compared with that in vacuo. 

Fig. 3.3. Absorption of neon-xenon gas mixtures at 295 K and the fixed frequency of 4.4 cm-1 as function of the product of neon and xenon density [132]. Three ratios of Ne and Xe densities are used k = 1.95 ( ) 1.53 (x) and 0.59 ( ). Reproduced with permission from the National Research Council of Canada, from [132].

Figure 3.3 shows the microwave collision-induced absorption coefficient of a neon-xenon gas mixture as function of the product of the Ne and Xe densities the ratios of Ne to Xe densities are k = 1.95, 1.53 and 0.59... 

Xenon fluorides are also excellent fiuorinaiors. though not so reactive as KiF2 (see below). They are often dean." the only by-product being xenon gas ... 

A glass bulb with a stopcock weighs 66 3915 g evacuated, and 66 6539 g when filled with xenon gas at 25°C The bulb holds 50 0 ml of water What is the density of xenon at 25°C9... 

In the experiments illustrated above, a remarkable amount of information becomes available rather quickly and easily when flowing HP xenon gas is used as a probe material. Although some of the information could have been obtained with thermally polarized xenon, such experiments would have to be carried out on sealed, pressurized samples, but to obtain information on the temperature-programmable interlayer void space would be far more difficult if not impossible. 

Equilibrium pressure 400 torr. Chemical shifts are given in ppm from xenon gas at zero pressure. 

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