Doser

A number of potential sources of error must be taken into account. In the volumetric method the following items need attention (a) constancy of the level of liquid nitrogen (b) depth of immersion of the sample bulb ( S cm) (c) temperature of sample (monitoring with vapour pressure thermometer close to sample bulb) (d) purity of adsorptive (preferably 99-9 per cent) (e) temperature of gas volumes (doser, dead space), controlled to 01 C. 

Let us first have a doser look at the dependence of the signal on the application of a pair of gradients with equal duration and intensity but opposite direction. This pair represents a two-fold encoding of position into the phase of the spins the total phase can be written as... 

Fig. 2. Schematic diagram of a high resolution He time-of-flight spectrometer. N-nozzle beam source, SI, 2-skimmers, Al-5 - apertures, T - sample, G - gas doser, CMA - Auger Spectrometer, IG - ion gun, L - LEED, C -magnetically suspended pseudorandom chopper, QMA-detector, quadrupole mass analyzer with channeltron.

Doser, C. Zschocke, P. Biedermann, J. Sussmuth, R. Trauter, J. Mikrobieller Abbau von Polyacrylsaureschlichten. Textilveredlung 1997, 32, 245-249. 

Effects of Water Chemistry on Bioavailability and Toxicity of Waterborne Cadmium, Copper, Nickel, Lead, and Zinc on Freshwater Organism Meyer, Clearwater, Doser, Rogaczewski, Hansen 2007... 

Bender, B., Wamboldt, F.S., O Connor, S.L., Rand, C., Szefler, S., Milgrom, H., and Wamboldt, M.Z. (2000) Measurement of children s asthma medication adherence by self report, mother report, canister weight, and Doser CT. Ann Allergy Asthma Immunol 85 416-421. 

Gas exposures are reported in units of Langmuir (1 Langmuir = 1 L = 1x10 torr-sec), uncorrected for ion gauge sensitivity and doser enhancement. Coverages, 0, are reported relative to the unreconstructed Au(lll) surface atom density (0 = 1 corresponds to 1.39x10 5 atoms/cm ). 

K. Freudenberg and A. Doser, Zur kenntnis der Aceton-zucker, V Die Symhese von Amine Hexosen aus Galaktose, Chem. Ber. 58 294 (1925). 

Figure 4 Comparison of the m/e = 80 TPD spectra obtained after dosing a clean Au(poly) surface with d6-PC at 150 K with the filaments of the mass spectrometer, ion gauge and electron gun turned off (0.23 L d6-PC, curve a) and on (0.1 L d6-PC, curve b). The m/e = 80 TPD spectra shown in curve c were obtained by condensing ultrapurified d6-PC (1 L), which had been left in the doser for several days, onto the gold surface. Heating rate 3 K/s. (From Ref. 4.)...

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