Sources of Negative Ions

Negative Ions. Negative ions in flames have been studied less widely than positive ions because they are present in much smaller concentrations typically, n+//i 100. The primary source of negative ions has been suggested (20) to be Reaction 3, comparable to Reaction 4 (see the section on flames with halogen additives). 

The steady state is established after about 3 ms, and the radical density is less than 0.1% from Sitf4. Thus, the dissociative attachment is the main initial source of negative ions in the system. 

SNICS (Source of Negative Ions hy Cesium Sputtering)... 

You have already had considerable experience with carbanionic compounds and their applications in synthetic organic chemistry The first was acetyhde ion m Chapter 9 followed m Chapter 14 by organometallic compounds—Grignard reagents for example—that act as sources of negatively polarized carbon In Chapter 18 you learned that enolate ions—reactive intermediates generated from aldehydes and ketones—are nucleophilic and that this property can be used to advantage as a method for carbon-carbon bond formation... 

M. Tabrizchi and A. Abedi, A novel electron source for negative-ion mobility spectrometry. International Journal of Mass Spectrometry, 218 (2002) 75—85. 

Secondary ion sources (using primary ion beams to sputter solid sample surfaces) are applied not only in SIMS and SNMS, but also for the formation of negative ions in accelerator mass spectrometry (AMS). 

The other source of congestion is due to the molecular core. It is most readily discussed using the inverse Bom-Oppenheimer point of view to define the zero-order quantum numbers. Here each state of the ionic core has its very own series of high Rydberg states. The physical reality of this approximation is the observation [36,43] of the long-time stable ZEKE states not just below the lowest ionization threshold but also just below the threshold of ionization processes that leave an excited ionic core. Indeed, it is for this very reason that ZEKE spectroscopy is useful for the spectroscopy of ions (or for such neutrals that are produced by ionization of negative ions... 

Except for its source of outside current, the electrolytic cell has the same elements as the electrochemical cell an anode and a cathode placed in an electrolyte in which cations (positive ions) move toward the cathode, and anions (negative ions) move toward the anode. The oxidation half reaction at the anode and the reduction half reaction at the cathode can be added together to find the overall redox reaction for the cell. The process is called electrolysis. If a coating of silver metal is desired on a piece of silver jewelry, electrolysis can be performed to coat or plate the silver jewelry in an electrolytic cell. The electrolyte silver nitrate (AgN03) solution supplies a source of silver ions (Ag+). The cathode is the silver jewelry, from which silver ions are reduced to silver metal. The anode... 

The translational energy releases reported in the literature for metastable ion decompositions are contained in Tables 1—7. Decompositions of positive ions occurring within an ion source are covered in Table 8 and decompositions of negative ions in an ion source in Table 9. Translational energy releases determined by photoion—photoelectron coincidence (PIPECO) appear, therefore, in Table 8. The results from the extensive series of electron impact (El) measurements [310] at ionizing energies close to threshold appear in Tables 8 and 9. Coverage of dissociations of diatomic ions is not exhaustive. 

Translational energy release accompanying decomposition of negative ions in ion source... 

Anion photoelectron spectroscopy is conducted by crossing a mass-selected beam of negative ions with a fixed-frequency photon beam and energy-analyzing the resultant photodetached electrons (Figure 21-8). There are three main regions of such an apparatus the source that generates the anions to be studied, the mass... 

Metal hydride reagent (Section 12.2) A reagent containing a polar metal-hydrogen bond that places a partial negative charge on the hydrogen and acts as a source of hydride ions (H ). 

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