Multiply-charged

Singly, doubly, triply, etc. charged ion. An atom, molecule, or molecular moiety that has gained or lost one, two, three, or more electrons. The term multiply charged ion is used to refer to ions that have gained or lost more than one electron where the number of electrons lost or gained is not designated. 

Partial charge-transfer reaction. An ion/neutral reaction that reduces the charge on a multiply charged reaction ion. 

Multiply charged ions such as adsorb on an ionic surface more strongly than singly charged ions such as Cl. The addition of a solution of... 

The implanted ion can be singly or multiply charged and can be any isotope. The mass separation system is used to avoid contamination. As an example, when implanting silicon the isotope is often used instead of to avoid contamination from the signals. After mass... 

Many metal ions react with water to produce hydrolysis products that are multiply charged inorganic polymers. These may react specifically with negative sites on the colloidal particles to form relatively strong chemical bonds, or they may be adsorbed at the interface. In either case, the charge on the particle is reduced. 

The spark source is an energetic ionization process, producing a rich spectrum of multiply charged species (Af/2, Af/3, Af/4, etc.). These masses, falling at halves, thirds, and fourths of the unit mass separation can aid in the positive identification of elements. In Figure 2, species like Au and are labeled. The most abundant... 

In contrast to most other ionization methods, the majority of ions produced by electrospray are multiply charged. This is of great significance as the mass spectrometer measures the m/z (mass-to-charge) ratio of an ion and the mass range of an instrument may therefore be effectively extended by a factor equivalent to the number of charges residing on the analyte molecule, i.e. an ion of m/z 1000 with... 

What multiple charging does not do, however, is to provide an equivalent increase in the resolution of the mass spectrometer and the resolution required to separate the individual isotopic contributions from a multiply charged species is identical to that required for the corresponding singly charged species. Figures 4.16 and 4.17 show the ions from the 7- - charge state of aprotin at resolutions of 1500 and 5000, respectively. 

Electrospray ionization, in contrast to the majority of other ionization methods employed in mass spectrometry, produces predominantly multiply charged ions of the intact solute molecule. This effectively extends the mass range of the mass spectrometer and allows the study of molecules with molecular weights well outside its normal range. 

Electrospray is unusual in that it produces almost exclusively multiply charged ions in a variety of different charge states. The way in which the molecular weight of an analyte may be calculated has been derived. In addition, the appearance of an electrospray spectrum may vary considerably with the conditions in the solution from which it has been generated. Eor this reason, the mechanisms leading to the production of ions using this technique have been described at some length. 

Multiply charged ion An ion with more than one charge. The electrospray spectra from compounds of high molecular weight contain exclusively multiply charged ions. 

Transformation The mathematical process of changing a raw electrospray spectrum containing a number of multiply charged ions into a mass spectrum plotted on a true mass scale. 

AB cements are not only formulated from relatively small ions with well defined hydration numbers. They may also be prepared from macromolecules which dissolve in water to give multiply charged species known as polyelectrolytes. Cements which fall into this category are the zinc polycarboxylates and the glass-ionomers, the polyelectrolytes being poly(acrylic acid) or acrylic add copolymers. The interaction of such polymers is a complicated topic, and one which is of wide importance to a number of scientific disciplines. Molyneux (1975) has highlighted the fact that these substances form the focal point of three complex and contentious territories of sdence , namely aqueous systems, ionic systems and polymeric systems. 

The main characteristics of electrospray ionisation are given in Table 6.21. Electrospray ionisation is a suitable technique for producing accurate molecular mass information on a wide range of low-MW samples. ESI-MS is particularly appealing for polar, high-MW samples (more than ca. 1000 Da), where the multiply charged ions formed have m/z values within the range of the spectrometer. However, ESI presents some problems in the identification of unknowns ... 

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