Silver ions, mass spectrometry

Secondary-ion mass spectrometry (SIMS) has been applied to the study of some silver complexes.511 For [Ag(py)4]S208 however, although the spectrum obtained was rich in fragment ions, no AgL spedes could be detected. Doubly charged spedes are not commonly observed in SIMS analyses and the reduced form of the intact cation, i.e. [Ag(py)4]+, was apparently not sufficiently stable in the gas phase. 

Secondary-ion mass spectrometry (SIMS) of [Ag(bipy)2]2+ yields a spectrum identical to that of the silver(I) complex, showing peaks attributable to (L + H)+, Ag+ and AgL+. This suggested facile reduction occurred to the unipositive cation. 30... 

A sample of a composition, nominally containing 22 ppm silver in water, was analyzed by time-of-flight secondary ion mass spectrometry (TOF-SIMS) in order to determine the form of silver in the composition. The conclusion is that the bulk of the silver exists as silver (0) [that is, metallic silver] and that there is a surface coating which as on average a composition of silver (II) oxide [AgO]. As mentioned above silver (II) oxide is usually a stoichiometric combination of silver (I) and silver (III). 

Figure 41 High-resolution secondary ion mass spectrometry (SIMS) images on silver halide microcrystals. Large crystal at top is 6.5 pm across. Crystals have four alternating layers of AgBr and AgBr09I0 on a AgBr core. A, Br image b, I- after -3 nm removed c, I- after 24 nm removed d, I" after -46 nm removed. (From Ref. 133.)...

Secondary-ion mass spectrometry (SIMS) of a thin layer of nucleic acid bases deposited on a silver foil under bombardment with Ar ions at 3 kV gives intense pseudomolecular ions [M H] but practically no simple bond cleavage fragments. Another new technique is that of (pulsed) laser induced desorption (LD). When applied to nucleotide bases such as cytosine or adenine (266 nm, quadruplet neodymium laser or 347 nm, ruby laser) the technique has good detection limits, particularly for ions with a short lifetime (up to 100 nsec). The technique makes use of a time-of-flight instrument and is utilized in both modes, positive (PI) and negative ions (NI). Both bases exhibit an intense [BH]" ion. These results are similar to those obtained by Cf plasma desorption (PD). 

Calculations for unreconstructed AgBr (100) surfaces indicate that surface rumpling occurs as halide ions relax outwards and silver ions move in toward the bulk [35]. The results of fluorescence SEXAFS measurements are consistent with the presence of such surface rumpling [47]. The calculations also indicate that rumpling is enhanced by the presence of iodide at the surface and that surface iodide ions have a marked propensity to cluster. These predictions are consistent with the observation of enhanced iodide concentrations at surfaces in AgBr, yIy thin films and emulsion grains, as measured by secondary ion mass spectrometry and ion scattering spectrometry [48,49]. 

Secondary ion mass spectrometry (SIMS) has also found application in the analysis of organic compounds not prone to thermal evaporation. By this technique sulfanilic acid gave fair abundancies of [M —H] ions15, when bombarded with low primary-ion current densities on a silver target. Sulfonic acids were successfully tested by atmospheric-pressure ion evaporation mass spectrometry and found to produce characteristic negative cluster ions16. 

An example for plasma ion mass spectrometry is the investigation of a silver solution at a concentration of 3 mg/1 When a sample of this solution is nebulized,... 

The isotopic peaks of silver Ag" and ° Ag" suggest a high sensitivity for this metal. Metal impurities of Na, Cu and Cu are detected besides peaks due to organic ions. Furthermore, corresponding to m/z 19 (OHj ) and m/z 30 (NO" ") which come from nitrogen, oxygen, carbon dioxide, and water present in the carrier gas argon are found. The method of plasma ion mass spectrometry is very sensitive and only small amounts of sample are used. The detection limit for some metals (Ag, As, Co, Pb) is below 1 ppb. 

Gillen, G., Bennett, X, Tarlov, M.J., Burgess, D.R.F. Jr. (1994) Molecular imaging secondary ion mass spectrometry for the characterization of patterned self-assembled monolayers on silver and gold. Ana/. C/jem., 66,2170-2174. 

Pettit, G.R., C.W. Holzapfel, and G.M. Cragg Mass Measurements of Natural Products by Solution Phase Secondary Ion Mass Spectrometry Employing Silver(I) and Thallium (I) Derivatives. J. Nat. Prod. 47, 941 (1984). 

CsFeo.72Agi.28Te2,1053 and Cs2Ag2ZrTe4. The latter has a structure that comprises 2D slabs of Ag- and Zr-centered tetrahedral separated by Cs+ cations.1054 Gas-phase silver chalcogenide ions of the type [Ag2 i E ] (E = S, Se, Te) with < 14 have been investigated by laser-ablation Fourier transform ion cyclotron resonance mass spectrometry.1055... 

Goldenfeld, I.V. Veith, H.J. A New Emitter for Field-Desorption Mass Spectrometry with Silver-Electroplated Micro-needles. Int. J. Mass Spectrom. Ion Phys. 1981,40, 361-363. 

Gautier C., Bourgeois M., Isnard H., Nonell A., Stadeknann G. Goutelard E. Development of cadmium/silver/palladium separation by ion chromatography with quad-mpole inductively coupled plasma mass spectrometry detection for off-line cadmium isotopic measurements. Journal of Chromatography A 2011 1218 (31)5241-5247. 

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