INDEX ions measured

Table 11.1. Physical properties of hydrocarbon films deposited with a remote electron cyclotron resonance plasma from three different C2Hz source gases at three different dc self-bias voltages 1% np represents the parallel component of the real part of the refractive index as measured by in situ ellipsometry. The film composition is obtained from ion-beam analysis. The total particle number densities nc and n-H are calculated from the stoichiometry and the film thickness. Deposition parameters pressure p = 0.2 Pa adjusted with gas flow at constant pumping speed, absorbed microwave power density P = 10 kW nT3 [17]...

Worked example 5.9 - cation-exchange capacity and % base saturation One method to measure the CEC of a soil is to leach a column containing a known weight of soil with a solution of a salt so that the exchange sites are saturated with the cation (index ion). After washing out the excess salt solution, a different salt solution is leached through the column and the exchangeable ions displaced, collected in a known volume and their concentration measured. 

Various detection systems can be used in ion-exclusion chromatography, among them ultraviolet (UV)/vis spectrophotometry, conductivity, electrochemistry, fiuorometry, refractive index (RI) measurement, are the most common techniques. Additionally, combined detection systems (e.g., UV/amperometry, UV/RI) may be used, leading to enhanced selectivity. 

In any determination of PZC, the ions that occupy the exchange sites and are subjected to measurement, called the index ions, are chosen based on their tendency to adsorb by essentially nonselective electrostatic bonds. These ions may not be in direct contact with the surface, being readily exchangeable by other ions of like charge. Salts of these ions (for example, NaCl, KNO3) are referred to as indifferent... 

The mixtures were equilibrated for 1-3 days in a thermostat. The ammonium ion content was determined by the Kjeldahl method. The 2 4 was precipitated as NH MgPO, and the exceds magnesium was titrated complex-imetrically. The refractive index was measured with a IRF-22 refractometer. 

The dielectric constant is a measure of the ease with which charged species in a material can be displaced to form dipoles. There are four primary mechanisms of polarization in glasses (13) electronic, atomic, orientational, and interfacial polarization. Electronic polarization arises from the displacement of electron clouds and is important at optical (ultraviolet) frequencies. At optical frequencies, the dielectric constant of a glass is related to the refractive index k =. Atomic polarization occurs at infrared frequencies and involves the displacement of positive and negative ions. 

The theory of counterion condensation is implicit in Oosawa (1957) but the term was coined later (Imai, 1961). The phenomenon was demonstrated by Ikegami (1964), using refractive index measurements of the interaction between sodium and polyacrylate ions. It has since been confirmed for many mono-, di- and trivalent counterions and polyionic species (Manning, 1979). 

The indexed relative sensitivity factor approach obviates the necessity of measuring the relative sensitivity factors from all possible matrices, by transferring relative sensitivity factors for elements between different matrices by using the matrix-dependence of characteristic intensity ratios in the spectra. Calibration curves are constructed relating RSFs for an element in a matrix to the matrix ion species ratio (e.g. M2+/M+ for element M) generated from a single standard. 

Pentane and ethane (end products of n-6 and n-3 polyunsaturated fatty acid peroxidation, respectively) in expired air are useful markers of in vivo lipid peroxidation. Nevertheless, when gas chromatography is used to measure hydrocarbons, some technical difficulties may be experienced because chromatographic resolution of pentane from isoprene and isopentane is extremely difficult to achieve. Another possible problem could be the presence of these gases as contaminants in atmosphere. Furthermore, the production of hydrocarbon gases depends on the presence of metal ions to decompose lipid peroxides. If such ions are only available in limited amounts, this index may be inaccurate. 

Cr + ions in aluminum oxide (the ruby laser) show a sharp emission (the so-called Ri emission line) at 694.3 nm. To a good approximation, the shape of this emission is Lorentzian, with Av = 330 GHz at room temperature, (a) Provided that the measured peak transition cross section is c = 2.5 x 10 ° cm and the refractive index is = 1.76, use the formula demonstrated in the previous exercise to estimate the radiative lifetime, (b) Since the measured room temperature fluorescence lifetime is 3 ms, determine the quantum efficiency for this laser material. 

Ni + ions show a broad absorption blue band that peaks at 405 nm in Mgp2 crystal, a tunable laser system. For a concentration of 2 x 10 ° cm Ni + ions, the absorption coefficient measured at 405 nm is 7.2 cm and the full width at half maximum is 8.2 x 10 Hz. Taking into account a refractive index of 1.39 for the Mgp2 crystal, estimate the oscillator strength, /, of the transition responsible for the mentioned absorption band. 

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