scholarly journals Quantum Phenomena and the Mobility of Potassium Ions in Argon

1974 ◽  
Vol 27 (2) ◽  
pp. 227 ◽  
Author(s):  
RO Watts
Keyword(s):  
Alkali Metal ◽  
Pressure Dependence ◽  
Room Temperature ◽  
Quantum Mechanical ◽  
Alkali Metal Ions ◽  
Potassium Ions ◽  
Zero Field ◽  
Mechanical Methods ◽  
Quantum Phenomena ◽  
Reduced Mobility

Recent work on the mobilities of alkali metal ions in the noble gases has indicated that there is a pressure dependence of the zero-field reduced mobility. The possibility of temporarily bound dimmers being responsible for this pressure dependence is examined here by quantum mechanical methods for the case of potassium ions in argon and it is shown that the conditions needed for a small pressure dependence do exist at room temperature.

scholarly journals The Effect of Clustering on the Measurement of the Mobility of Potassium Ions in Nitrogen Gas

1972 ◽  
Vol 25 (4) ◽  
pp. 465 ◽  
Author(s):  
EW McDaniel
Keyword(s):  
Room Temperature ◽  
Pressure Effect ◽  
Gas Pressure ◽  
Potassium Ions ◽  
Zero Field ◽  
Nitrogen Gas ◽  
Pressure Calibration ◽  
Reduced Mobility ◽  
Low Pressures ◽  
Source Of Error

McDaniel and Martin (1971) have suggested that the zero-field reduced mobility of (unclustered) K+ ions in nitrogen at room temperature and low pressures (~ 0�1 torr) is accurately enough known to be useful in pressure calibration of drift tubes and other types of apparatus employed in atomic collision experiments, where the uncertainty in the value of the gas pressure frequently represents the largest source of error in the measurements. Elford (1971) has questioned the validity of this suggestion on the grounds that he has observed a very slight, explicit dependence of the reduced mobility of K+ ions on the gas pressure in drift tube experiments with nitrogen and other gases. Although this pressure effect cannot be reconciled with existing mobility theory (McDaniel and Mason 1972), Elford believes the effect to be real and hence maintains that in fact the true mobility of unclustered K+ ions in nitrogen is not accurately known. The purpose of this communication is to point out that Elford's experiments with nitrogen were conducted at pressures sufficiently high that significant clustering of nitrogen molecules with his K+ ions inevitably occurred and that consequently the suggestion of McDaniel and Martin (1971) is not weakened by his findings.

Conformational Analysis and Binding Affinity Determination for Host—Guest Complexation of Alkali Metal Ions with Bis-Crown Ethers by Electrospray Mass Spectrometry and Molecular Modeling

2002 ◽  
Vol 8 (5) ◽  
pp. 375-380 ◽  
Author(s):  
Hui-Fen Wu ◽  
Shun-Min Huan ◽  
Chun-Fu Wu
Keyword(s):  
Mass Spectrometry ◽  
Alkali Metal ◽  
Metal Ions ◽  
Binding Affinity ◽  
Alkali Metal Ions ◽  
Ionization Mass ◽  
Potassium Ions ◽  
Esi Ms ◽  
Sandwich Type

This study presents the application of electrospray ionization mass spectrometry (ESI/MS) to investigate the host–guest complexation phenomenon for an array of alkali metal ions with bis[(benzo-15–crown-5)-15–ylmethyl] pimelate (BBCP). The results have shown that potassium ions possess the best binding affinity with the BBCP, owing to formation of the very stable sandwich-type (1:1) complexes and the strong K+ cation-π electron interactions between the K+ ion and the benzene rings of BBCP. The results of the competition experiments indicate the selectivity for BBCP toward the alkali metal ions is K+ > Rb+ > Cs+ > Na+ > Li+. In addition, combining the results of ESI/MS and molecular mechanics conformational searches reveal that the formation of sandwich-type (1:1) complexes can be observed for larger metal ions including K+, Rb+ and Cs+. As for Na+ ions, both 1:1 and 1:2 complexes can be observed.

scholarly journals Pressure Dependence and End Effects in Precision Ion Mobility Studies

1974 ◽  
Vol 27 (2) ◽  
pp. 211 ◽  
Author(s):  
MT Elford ◽  
HB Milloy
Keyword(s):  
Pressure Dependence ◽  
Zero Field ◽  
Surface Layers ◽  
End Effects ◽  
Pressure Limit ◽  
Fitting Procedure ◽  
Resonant States ◽  
Mobility Studies ◽  
Cluster Ion ◽  
Reduced Mobility

The mobilities of K + ions have been measured by the Bradbury-Nielsen method in He, Ar, H2 and N 2 at 293 K at pressures and E/Nvalues in the range 1�4-190 torr and 1-28 Td respectively. Three drift tubes were used with drift lengths of 3� 395, 9� 076 and 50�00 cm. The anomalous variation of the reduced mobility with E/ N at low values of E/ N reported by Elford (1971) has been shown to be due to the presence of charged surface layers on the first grid of the time-of-flight system. The dependence of the reduced mobility on pressure also reported by Elford has been confirmed, and an explanation of the pressure dependence in He, Ar and H2 is proposed in terms of the formation of ion-atom or ionmolecule complexes in orbiting resonant states. The zero-field reduced mobilities in the zero-pressure limit have been derived by a fitting procedure and found to be 21 �3 � O' 2, 2�64 � O� 02 and 12� 8 � O' 1 cm2 y-1 S-l for He, Ar and H2 respectively. The pressure dependence of the reduced mobility for K + ions in N2 is shown to be of a different form from the other gases investigated and to be due to the formation of the cluster ion K + . N2. The present data are consistent with the equilibrium constant of Beyer and Keller (1971) for the reaction K + + N2 + N2 +� K + . N2 + N2. The zero-field reduced mobility for K+ ions in N2 in the zero-pressure limit has been found to be 2�50�0�02 cm2 Y-1 s-1.

Abnormal site occupancy and high performance in warm WLEDs of a novel red phosphor, NaHF2:Mn4+, synthesized at room temperature

2017 ◽  
Vol 46 (40) ◽  
pp. 13835-13844 ◽  
Author(s):  
Luqing Xi ◽  
Yuexiao Pan ◽  
Mengmeng Zhu ◽  
Hongzhou Lian ◽  
Jun Lin
Keyword(s):  
Alkali Metal ◽  
Metal Ions ◽  
High Performance ◽  
Room Temperature ◽  
Site Occupancy ◽  
Luminescence Properties ◽  
Alkali Metal Ions ◽  
Red Phosphor ◽  
Red Phosphors ◽  
Novel Strategy

A novel red phosphor, NaHF2:Mn4+, was obtainedviasubstituting Na+located at the center of the octahedron with Mn4+. This work provides a novel strategy to develop novel Mn4+doped red phosphors with controlled luminescence properties by substituting for alkali metal ions.

18O/16O and D/H Isotopic Preference in Hydration Spheres of Alkali Metal Ions

2011 ◽  
Vol 66 (8-9) ◽  
pp. 569-575 ◽  
Author(s):  
Takao Oi
Keyword(s):  
Partition Function ◽  
Alkali Metal ◽  
Bulk Water ◽  
Alkali Metal Ions ◽  
Water Molecules ◽  
Molecular Orbital Calculations ◽  
Potassium Ions ◽  
Hydration Sphere ◽  
Sodium And Potassium ◽  
Model Water

Abstract With the final goal set at theoretical elucidation of experimentally observed isotope salt effects, molecular orbital calculations were performed to estimate the 18O/16O and D/H isotopic reduced partition function ratios (RPFRs) of water molecules around lithium, sodium, and potassium ions. As model water molecules in the ith hydration sphere of the cation in aqueous solutions containing that cation, we considered water molecules in the ith hydration sphere that were surrounded by water molecules in the (i+1)th hydration sphere in clusters, M+(H2O)n (M = Li, Na or K; n up to 100). The calculations indicated that the decreasing order of the 18 O preference over 16 O in the primary hydration sphere is: Li+ > (bulk water) ≥ Na+ > K+. That is, water molecules in the primary hydration spheres of the Li+, Na+, and K+ ions are, respectively, enriched, slightly depleted, and depleted in the heavier isotope of oxygen relative to water molecules in bulk. No such preference was observed for hydrogen isotopes in any hydration sphere or for oxygen isotopes in the secondary and outer hydration spheres.

Room Temperature Alkali Metal Reduction of Carbon Dioxide

2020 ◽  
Author(s):  
Lucas A. Freeman ◽  
Akachukwu D. Obi ◽  
Haleigh R. Machost ◽  
Andrew Molino ◽  
Asa W. Nichols ◽  
...  
Keyword(s):  
Alkali Metal ◽  
Alkali Metals ◽  
Room Temperature ◽  
Chemical Reduction ◽  
Bond Cleavage ◽  
Open Shell ◽  
Metal Reduction ◽  
One Pot ◽  
Earth Abundant ◽  
Electron Reduction

The reduction of the relatively inert carbon–oxygen bonds of CO<sub>2</sub> to access useful CO<sub>2</sub>-derived organic products is one of the most important fundamental challenges in synthetic chemistry. Facilitating this bond-cleavage using earth-abundant, non-toxic main group elements (MGEs) is especially arduous because of the difficulty in achieving strong inner-sphere interactions between CO<sub>2</sub> and the MGE. Herein we report the first successful chemical reduction of CO<sub>2</sub> at room temperature by alkali metals, promoted by a cyclic(alkyl)(amino) carbene (CAAC). One-electron reduction of CAAC-CO<sub>2</sub> adduct (<b>1</b>) with lithium, sodium or potassium metal yields stable monoanionic radicals clusters [M(CAAC–CO<sub>2</sub>)]<sub>n</sub>(M = Li, Na, K, <b> 2</b>-<b>4</b>) and two-electron alkali metal reduction affords open-shell, dianionic clusters of the general formula [M<sub>2</sub>(CAAC–CO<sub>2</sub>)]<sub>n </sub>(<b>5</b>-<b>8</b>). It is notable that these crystalline clusters of reduced CO<sub>2</sub> may also be isolated via the “one-pot” reaction of free CO<sub>2</sub> with free CAAC followed by the addition of alkali metals – a reductive process which does not occur in the absence of carbene. Each of the products <b>2</b>-<b>8</b> were investigated using a combination of experimental and theoretical methods.<br>

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