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Mass Spectroscopy
Published in Thomas J. Bruno, Paris D.N. Svoronos, CRC Handbook of Basic Tables for Chemical Analysis, 2020
Thomas J. Bruno, Paris D.N. Svoronos
The table below lists some common spectral interferences that are encountered in inductively coupled plasma mass spectrometry (ICP-MS) as well as the resolution that is necessary to analyze them [1]. The resolution is presented as a dimensionless ratio. As an example, the mass of the polyatomic ion 15N16O+ would be 15.000108 + 15.994915 = 30.995023. This would interfere with 31P+ at a mass of 30.973762. The required resolution would be RMM/ΔRMM or 30.973762/0.021261 = 1457. One should bear in mind that as resolution increases, the sensitivity decreases with subsequent effects on the price of the instrument. Note that small differences exist in the published exact masses of isotopes, but for the calculation of the required resolution, these differences are trivial. Moreover, recent instrumentation has provided rapid, high-resolution mass spectra with an uncertainty of <0.01 %.
Defect Chemistry in Solid State Electrochemistry
Published in P.J. Gellings, H.J.M. Bouwmeester, Electrochemistry, 2019
Orientational disorder in ionic solids arises because a diatomic or polyatomic ion has available to it two or more distinguishable orientations in the crystal lattice. This kind of disorder is a fairly common occurrence, especially when the polyatomic ions are sufficiently symmetrical. If these ions are associated with monoatomic ions of opposite charge, the situation simplifies in that the diatomic or polyatomic ions are to some extent protected from interference from ions of the same kind by the intervening shell of the monoatomic ions. Switching of diatomic or polyatomic ions from one orientation to another may induce local stress and hence facilitate the displacement of the monoatomic ion. A crystal can have positional disorder and at the same time orientational disorder of a polyatomic ion or molecule. Examples of this behavior are provided by lithium iodide monohydrate, and the high-temperature form of lithium sulfate.
Fabrication of Nanomaterials
Published in C. Anandharamakrishnan, S. Parthasarathi, Food Nanotechnology, 2019
R. Preethi, Leena Maria, J.A. Moses, C. Anandharamakrishnan
Polyoxometalate (POM) is a polyatomic ion, a combination between oxygen and early transition metals at their highest oxidation states. POMs are the potential candidate in synthesizing nanoparticles, notably silver nanoparticles, because they are soluble in water and can go through a stepwise process and multielectron redox reactions without interrupting their structure. This is a one-step synthesis method, where POMs act as a reducing and stabilizing agent. The particle size and shape can be varied based on the selection of different POMs. POM-based nanoparticles are used to construct various electrochemical cells and photoelectronic sensor devices (Bhosale et al., 2014).
Atoms do exist in molecules: analysis using electrostatic potentials at nuclei
Published in Molecular Physics, 2022
Peter Politzer, Jane S. Murray
For a free atom, the electrostatic potential at its nucleus is due entirely to its electrons. If this were to be subtracted from the total electronic potential at the nucleus of a molecule or polyatomic ion, this would give the potential due to the electrons in the remainder of that molecule or ion, not including those of the atom itself. The results for ten atoms are in Table 2. The V0,A values are from Table 1 [29]. The V0,n (nuc) values are simply the electrostatic potentials at nucleus A created by all other nuclei in the molecule or ion. V0,e (elect) is the difference between V0,A and V0,n (nuc). Finally, the V0,A (elect)* values are obtained by subtracting V0,A of the free atom A from V0,e (elect).
Descendant of the X-ogen carrier and a ‘mass of 69’: infrared action spectroscopic detection of HC3O+ and HC3S+
Published in Molecular Physics, 2020
Sven Thorwirth, Michael E. Harding, Oskar Asvany, Sandra Brünken, Pavol Jusko, Kin Long Kelvin Lee, Thomas Salomon, Michael C. McCarthy, Stephan Schlemmer
The prototypical acylium – formylium ion, HCO – was the first polyatomic ion detected in space, although its identity was originally a mystery when a strong line at 89.2 GHz was observed towards several astronomical objects; for lack of a better name, the line was dubbed ‘X-ogen’ [5] (‘extraterrestrial origin’). However, it was not until the pure rotational spectrum of this ion was measured by Woods and co-workers a few years later [6] that the carrier of the astronomical line was established with certainty, and in doing so confirmed the bold prediction of Klemperer [7]. Similarly, HCS was first detected in space [8] almost simultaneously with a report of its high-resolution laboratory spectrum [9]. Since then, HCO and HCS have been the subjects of a number of high-resolution spectroscopic investigations [10–17].
Fine tuning of hydrogen bond strength in crystals: a case study of O–H–O hydrogen bond in ammonium substituted potassium dihydrogen phosphate
Published in Molecular Physics, 2022
R. R. Choudhury, R. Chitra, S. Kesari, R. Rao, E. V. Selezneva, A. P. Dudka, I. P. Makarova
Potassium Dihydrogen Phosphate (KDP) is one of the most extensively studied hydrogen-bonded crystals because it has technologically relevant physical properties [4,5]. Its hydrogen bonds are examples for low barrier hydrogen bond (LBHB) [6]. This constitutes an essential category of hydrogen bonds found in a wide range of compounds, including biomolecules like enzymes [7]. Studies on the O–H–O hydrogen bond between phosphate groups in KDP have provided valuable insight into the essential nature of LBHB [8]. As stated earlier, hydrogen bonds are susceptible to the local environment, in KDP crystals (Figure 1), the O–H–O hydrogen bond is surrounded by Potassium ions (K+) that make co-ordinate bonds with the O atoms [6]. One way to change the local environment of these O–H–O hydrogen bonds is to replace some of the K+ ions with similar ions, which can be easily accommodated in the space occupied by K+ ions. One such ion very similar in size to K+ ions is the ammonium ion NH4+ [9,10]. In fact, K+ and NH4+ ions are so identical that while studying the uptake of K+ ions in bacteria, it was observed that under some growth conditions, NH4+ ions could, to a large extent, take over the physiological role of K+ ions, for example, NH4+ ions could activate enzymes requiring K+ ions [11]. Hence, investigating the changes brought about by the substitution of K+ ions by NH4+ ions is interesting from the point of view of material design and molecular biology. Although the ionic radii of K+ and NH4+ are comparable, 1.51 and 1.52 Å, respectively, there is a fundamental difference between the way the two ions interact with the surrounding [9,10]. K+ ion is a simple monoatomic ion. It interacts with the surrounding atoms through electrostatic interactions. But NH4+ ion is a polyatomic ion that could interact with the surrounding atoms through electrostatic interactions and make hydrogen bonds with the surrounding atoms. As reported earlier, even a small substitution of K+ ions by NH4+ ions in KDP crystals led to a significant change in their physical properties [12]. This study reports the results of diffraction and Raman spectroscopic investigations on KDP-type crystals with a small amount of K+ ions substituted by NH4+ ions. Diffraction techniques give a time and space average picture of the atoms in the crystals, whereas spectroscopic techniques provide information regarding the dynamic motion of the atoms; they complement each other to give the complete information about a crystal. Using the information provided by these investigations, correlations between the physical properties of the KDP-type crystals and the observed changes in the hydrogen bonding within the crystal are established.