Cadmium resonance

For these temperature studies the cadmium resonance source at 2288 A. (Cd—R source) was used, since the absorption coefficient of COS at... 

Figure 8.34 Time-resolved absorbance spectrum obtained for DORM-1 Dogfish Muscle reference material in the vicinity of the cadmium resonance hne at 228.802 nm pyrolysis temperature 800 °C atomization temperature 1600 °C iridium as permanent modifier direct solid sample analysis...

The linear concentration dependence (14) of the inorganic cadmium salts in aqueous solution could perhaps be explained by inner- or outer-sphere complexation with the given anion (12). At "infinite dilution," these cadmium resonances approach that for 0.1 molar aqueous cadmium perchlorate, the generally accepted standard for cadmium chemical shift measurements. 

Lability of ligands in cadmium complexes is known to affect NMR spectral parameters. The exchange contributes to cadmium lineshapes and peak splittings in phosphine adducts (37-39) and thiolatocadmates (24-27), to changes in observed cadmium-carbon scalar coupling, carbon linewidths, and cadmium chemical shifts in Cd-EDTA complexes (34), to enzymatic activity of metalloproteins (44), and to shifts in or disappearance of cadmium resonances in metalloproteins, e.g., carbonic anhydrase (45). 

In contrast to the low-pressure lamps (1—130 Pa) which primarily emit at the resonance line at A = 254nm, high-pressure lamps (lO —10 Pa) also produce numerous bands in the UV and VIS regions (Fig. 16). Table 3 lists the emission lines and the relative spectral energies of the most important mercury lamps (see also [44]). The addition of cadmium to a mercury vapor lamp increases the numbei of emission lines particularly in the visible region of the spectrum [45] so that it i. also possible to work at A = 326, 468, 480, 509 and 644 nm [46]. 

J. R. Harbour, R. Wolkow and M. L. Hair. (1981) Effect of platinization on the photoproperties of cadmium sulfide pigments in dispersion. Determination by hydrogen evolution, oxygen uptake and electron spin resonance spectroscopy. J Phys Chem 85 4026-4029... 

Resonance Lamp.—Such lamps (sometimes called low pressure lamps) are often used as line sources in photochemical studies. These usually contain a small amount of a metal vapor (e.g., mercury, cadmium, zinc, etc.) and several mm pressure of a rare gas. They operate at relatively low current (ca. 100 ma.) and high voltages (several thousand volts). This is in contrast to a typical medium pressure lamp which may operate off a 110-220 v. power supply delivering ca. 3-5 amp. The most common example in photochemistry is the mercury resonance lamp which has strong emission of the unreversed resonance lines at 2537 A. and 1849 A. (ca. 90% or more of the total) along with other, much weaker lines ( resonance lines are those which appear both in absorption and emission). There is little continuum. Sources of this type are widely used for photosensitized reactions. 

M.M. Lee and D.A. Russel, Novel determination of cadmium ions using an enzyme self assembled monolayer with surface plasmon resonance, Anal. Chim. Acta, 500 (2003) 119-125. 

Armitage, I.M., Pajer, R.T., Uiterkamp, A.J.M.S., Chlebowski,J.F. and Coleman, J.E. (1976) Cadmium-133 Fourier Transform nuclear magnetic resonance of cadmium(II) carbonic anhydrase and cadmium(II) alkaline phosphatase./. Am. Chem. Soc., 98, 5710-5712. 

With the main resonance line for cadmium at 228.8 nm, it is hardly surprising that this element is not determined usefully by flame AES. However cadmium is a very easily atomized element, and the determination by flame AAS is sensitive, with detection limits sometimes as low as 1 ng ml-1 often being cited for the air-acetylene flame.1 Determination by flame AFS may result in detection limits two orders of magnitude lower than this, if a suitable excitation source is available.12 The determinations in acetylene flames are virtually free from chemical interference. Because of the ease of atomization, the element may be readily determined using atom-trapping techniques or boat or cup techniques, as discussed in Chapter 6. Recently a cold vapour sample introduction technique has also been suggested for cadmium determination.13,14... 

High concentrations of cadmium are rare in environmental samples, so it is unusual to need to avoid dilution. This is perhaps just as well, because the second most sensitive wavelength for cadmium determination by flame AAS gives a sensitivity almost three orders of magnitude poorer than the main resonance line. 

Fluorescence.—When the vapour of phosphorus at 600° to 700° C. and 1 mm. pressure (therefore containing a considerable proportion of diatomic molecules) is confined in a sealed quartz tube and exposed to the spark fines 2195 and 2144 A of cadmium, 2100 and 2062 A of zinc or 1990 and 1935 A of aluminium, it gives a fluorescent emission consisting of a resonance series in the region 3500 to 1900 A.10... 

Collected Phase Information for Cerium-Cadmium Alloys. A partial phase diagram for the cerium-cadmium system is presented in Figure 1. The room temperature results are based on x-ray studies by Iandelli and Ferro (9), who studied slowly cooled samples. However, their CeCd6 is shown as a dashed line because nuclear magnetic resonance studies by Jackson and the authors (10) have shown that the compound is unstable at room temperature and can decompose to metallic cadmium and CeCd 4i5. Because of probable kinetic barriers, the absence of compounds intermediate between cadmium and CeCd 6 does not indicate that these intermediates are unstable at room temperature. 

J. A. Jackson, also of this laboratory, has made room temperature nuclear magnetic resonance studies of the Knight shift of cadmium in slowly cooled CeCd, 45 alloys with different compositions and different histories. All CeCd 4 5 samples tested showed a major peak at almost the same position and shifted from that of metallic cadmium. One sample showed only this peak, while others clearly showed satellite peaks either at larger or at smaller shift. Possibly some samples had small amounts of both satellite peaks, and there was apparently some further difference in the shapes of satellite peaks and of the major peak these latter observations are tenuous, however, since they were near the resolution limit of the apparatus. The differences apparently do not correlate simply with composition however, they may correlate with differences in microphase structures. 

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