Absorption methods

As an acoustic wave propagates it is attenuated by absorption in the medium. This process results in a radiation pressure which is proportional to the absorbed energy and acoustic streaming (vide supra). The pressure can be measured from the height difference of liquids in two connected tubes, one being sonicated and the other not, at different values of z where z is the distance from the emitter surface. If we let I2 be the sound intensity at z and Io the sound intensity at the surface of the emitter then, 

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Chapman W B, Blackman B W, Nizkorodov S and Nesbitt D J 1998 Quantum-state resolved reactive scattering of F + H2 in supersonic jets Nascent HF(v,J) rovibrational distributions via IR laser direct absorption methods J. Chem. Rhys. 109 9306-17... 

Walsh, A. The Development of Atomic Absorption Methods of Elemental Analysis 1952-1962, Anal Chem. 1991, 63, 933A-941A. 

Chemical Analysis. Chemical analysis is deterrnined with conventional atomic absorption methods. Rehable wet techniques are sometimes employed (see Table 5). 

Chemical Analysis. Chemical impurities commonly analyzed include Na20, Fe202, and Si02. The hydroxide is first dissolved in boiling concentrated HQ. Atomic absorption methods have replaced older colorimetric procedures. 

Surface Area. The most important features influencing the performance of carbon blacks are aggregate size and surface area. Surface area is measured by gas- and Hquid-phase adsorption techniques, and depends on the amount of adsorbate required to form a surface monolayer. If the area occupied by a single-adsorbate molecule is known, a simple calculation will yield the surface area. A low temperature nitrogen absorption method, based on the original method of Bmnauer, Emmett, and Teller (BET) (30), has been adopted by ASTM as standard method D3037-86 (2). 

On the basis of data obtained the possibility of substrates distribution and their D-values prediction using the regressions which consider the hydrophobicity and stmcture of amines was investigated. The hydrophobicity of amines was estimated by the distribution coefficient value in the water-octanole system (Ig P). The molecular structure of aromatic amines was characterized by the first-order molecular connectivity indexes ( x)- H was shown the independent and cooperative influence of the Ig P and parameters of amines on their distribution. Evidently, this fact demonstrates the host-guest phenomenon which is inherent to the organized media. The obtained in the research data were used for optimization of the conditions of micellar-extraction preconcentrating of metal ions with amines into the NS-rich phase with the following determination by atomic-absorption method. 

The mrboexpanders frequently used in refrigeration proeesses develop power, but reeovery of tills power has often been of seeondary unportanee. A number of power absorption methods are direetly applieable to energy reeovery expanders. 

Edmister Method (1947). Briefly, the Edmister absorption method (1947) with a known rich gas going to a fixed tower is as follows ... 

The usual method for the determination of phenols is based on the solubility of these compounds in solutions of caustic alkali. Such absorption methods are not strictly accurate, since a small portion of constituents other than phenols are dissolved by the alkali. So long, however, as the conditions are kept constant, useful comparative results are obtained. The process is best carried out as follows —... 

Filtered broth was passed at 2.5 ml/min through a resin column (2.5 cm diameter, 28 cm length) packed with 150 ml of ion exchange resin Amberlite IRC-50 sodium type (Rohm and Haas Co., U.S.A.). The column was washed with water, eluted with 0.5 N HCI at a flow rate 1.3 ml/min. The eluates were fractionated each 10 ml and tuberactinomycin-N activity was found at fractions No. 45-63 obsarved by ultraviolet absorption method and bioassay. 

Optical methods of analysis are dependent either upon (i) measurement of the amount of radiant energy of a particular wavelength absorbed by the sample, or (ii) the emission of radiant energy and measurement of the amount of energy of a particular wavelength emitted. Absorption methods are usually classified according to the wavelength involved as (a) visible spectrophotometry (colorimetry), (b) ultraviolet spectrophotometry, and (e) infrared spectrophotometry. 

Although not strictly absorption methods in the sense in which the term is usually employed, turbidimetric and nephelometric methods which involve measuring the amount of light stopped or scattered by a suspension should also be mentioned at this point. 

A. Sapinski, Arch Procesow Spalania 3 (2), 179-90 (1972) CA 78, 99929 (1973) Temp mesurement of a flame containing solid particles by the emission-absorption method The method was used for investigation of solid proplnts con-... 

The y-ray absorption method of determining in-line concentration (hold-up) of particles depends on the different degree to which the solid and the liquid attenuate y-rays details of the method are given in the literature 1314). 

Ward, F.N. Nakagawa, H.M. Harms, T.F. Von Sickle, G.H. Atomic Absorption Methods of Analysis Useful in Geochemical Exploration, Geological Survey Bulletin 1289, Reston, VA, 1969 1-45. 

There exist a number of other methods for the separation of diamondoids from petroleum fluids or natural gas streams (1) a gradient thermal diffusion process [54] is proposed for separation of diamondoids (2) a number of extraction and absorption methods [53,83] have been recommended for removing diamondoid compounds from natural gas streams and (3) separation of certain diamondoids from petroleum fluids has been achieved using zeolites [56, 84] and a number of other solid adsorbents. 

Reference methods are generally arrived at by consensus and fairly extensive testing by a number of laboratories. For example, the flame atomic absorption method for Ca in serum developed under the leadership of the agency fondly remembered as NBS, now NIST (Cali et al. 1972), was established after several inter-laboratory comparison exercises. The results were evaluated after each exercise and the procedure was changed as necessary. After five exercises, it was felt that the state-of-the-art had been reached, with the reference method being capable of measuring Ca in serum with an accuracy of 2% of the true value determined by IDMS (note that attainment of high accuracy and precision is not only a matter of the method, but is a function of both the method and analyst expertise). 

Ward FN, Nakagawa HM, Harms TF, VanSickle GH (t969) Atomic-absorption methods of analysis useful in geochemical exploration. U.S. Government Printing Office, Washington DC, 45 pp. 

UV3346) offer superior compatibility, low volatility, excellent resistance to extraction and contribute to heat stability. The nonextractable nature of these additives makes their quantification challenging. The quantification of Chimassorb 944 in polyolefins is possible using an UV absorption method after dissolution of the polymer [596]. 

Principles and Characteristics Flame emission instruments are similar to flame absorption instruments, except that the flame is the excitation source. Many modem instruments are adaptable for either emission or absorption measurements. Graphite furnaces are in use as excitation sources for AES, giving rise to a technique called electrothermal atomisation atomic emission spectrometry (ETA AES) or graphite furnace atomic emission spectrometry (GFAES). In flame emission spectrometry, the same kind of interferences are encountered as in atomic absorption methods. As flame emission spectra are simple, interferences between overlapping lines occur only occasionally. 

X-ray absorption method This method is similar to void fraction measurement by radiation attenuation. 

Photochemistry of Cr(CO) at 248 nm. We have previously shown8 that the 248 nm photolysis of Cr(CO)6 yields Cr(CO)4 as the principal organometallic product via (7)-(8). Time-resolved laser absorption methods can be used to record the... 

The determination of electron concentration by the frequency shift method is limited to time resolution greater than a few hundred nanoseconds and is therefore not applicable to liquids. The microwave absorption method can be used virtually down to the pulse width resolution. Under conditions of low dose and no electron loss, and assuming Maxwellian distribution at all times, Warman and deHaas (1975) show that the fractional power loss is related to the mean electron energy (E) by... 

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