Experimental evidence from liquid semiconductors

1977 ◽  
Vol 55 (11) ◽  
pp. 1961-1967 ◽  
Author(s):  
J. E. Enderby
Keyword(s):  
Electronic Structure ◽  
Alkali Metal ◽  
Experimental Evidence ◽  
Atomic Structure ◽  
Alkali Metals ◽  
The Other ◽  
Ionic Bonding ◽  
Liquid Semiconductors ◽  
Close Interaction ◽  
Semiconducting Alloys

Two broad types of liquid semiconducting alloys will be discussed, namely those involving alkali metals (e.g., the Li–Pb and the Cs–Au system) and those in which a chalcogen is involved (e.g., Cu–Te or Ni–Te). It will be argued that relatively simple ionic bonding schemes in alkali metal systems must be replaced by more complicated ones in chalcogen based alloys. The close interaction between atomic structure on one hand, and the electronic structure on the other will be emphasized.

Alkali-Metal Containing Amorphous Carbon: Reactivity and Electronic Structure

1999 ◽  
Vol 593 ◽  
Author(s):  
M. Töwe ◽  
P. Reinke ◽  
P. Oelhafen
Keyword(s):  
Electronic Structure ◽  
Alkali Metal ◽  
Work Function ◽  
Photoelectron Spectroscopy ◽  
Alkali Metals ◽  
Film Surface ◽  
Carbon Films ◽  
Metal Atoms ◽  
Sample Characterization

ABSTRACTAmorphous hydrogen-free carbon films (sp2-dominated a-C) were deposited under ultrahigh vacuum conditions between room temperature and 800°C. These films served as matrices for the in-situ incorporation of alkali-metal atoms (Li, Na). In-situ sample characterization was performed by photoelectron spectroscopy with both x-ray and ultraviolet excitation (XPS, UPS). While the clean metal-containing samples were prepared with metal contents of about 10 at%, a strong oxidation driven accumulation of metal atoms on the film surface exceeding 50 at% was observed upon exposure to molecular oxygen. Work-function measurements by UPS reflected the changes within the electronic structure of the material. Metal incorporation considerably decreased the work-function, but only after oxidation we observed work-functions below the values given for pure alkali metals.

Alkali metal adducts of benzophenone azine. II. The lithium adduct

1970 ◽  
Vol 48 (12) ◽  
pp. 1915-1918 ◽  
Author(s):  
E. J. MacPherson ◽  
James G. Smith
Keyword(s):  
Alkali Metal ◽  
Alkali Metals ◽  
Reducing Power ◽  
The Other ◽  
Organolithium Compounds ◽  
Metal Adducts ◽  
Sodium And Potassium

The behavior of benzophenone azine towards lithium has been studied. Unlike sodium and potassium, lithium effected extensive reduction and cleavage of benzophenone azine; the reaction product being benzhydryl amine. By limiting the amount of lithium to 2 g-atoms per mole of azine, the reaction product was shown to be N-lithiobenzophenone imine on the basis of its chemical behavior.Two reasons are advanced to explain the behavior of lithium in contrast to that of sodium or potassium. One explanation relies upon the greater reducing power of lithium compared with the other two alkali metals. The other relies upon the tendency of organolithium compounds to associate via formation of multi-center bonds.

Electronic structure of alkali metal chalcogenides

2015 ◽  
Vol 38 (0) ◽  
pp. 70-81
Author(s):  
Д. И. Блецкан ◽  
В. В. Вакульчак ◽  
А. В. Лукач
Keyword(s):  
Electronic Structure ◽  
Alkali Metal ◽  
Metal Chalcogenides

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>

scholarly journals Effect of the sample work function on alkali metal dosing induced electronic structure change

2021 ◽  
pp. 147045
Author(s):  
Saegyeol Jung ◽  
Yukiaki Ishida ◽  
Minsoo Kim ◽  
Masamichi Nakajima ◽  
Shigeyuki Ishida ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Alkali Metal ◽  
Work Function ◽  
Structure Change

scholarly journals Spotlight on Alkali Metals: The Structural Chemistry of Alkali Metal Thallides

Crystals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1013
Author(s):  
Stefanie Gärtner
Keyword(s):  
Crystal Structure ◽  
Alkali Metal ◽  
Crystal Structures ◽  
Alkali Metals ◽  
Valence Electron ◽  
Oxidation States ◽  
Valence Electron Concentration ◽  
Base Metals ◽  
Charge Balancing

Alkali metal thallides go back to the investigative works of Eduard Zintl about base metals in negative oxidation states. In 1932, he described the crystal structure of NaTl as the first representative for this class of compounds. Since then, a bunch of versatile crystal structures has been reported for thallium as electronegative element in intermetallic solid state compounds. For combinations of thallium with alkali metals as electropositive counterparts, a broad range of different unique structure types has been observed. Interestingly, various thallium substructures at the same or very similar valence electron concentration (VEC) are obtained. This in return emphasizes that the role of the alkali metals on structure formation goes far beyond ancillary filling atoms, which are present only due to charge balancing reasons. In this review, the alkali metals are in focus and the local surroundings of the latter are discussed in terms of their crystallographic sites in the corresponding crystal structures.

Electronic structure of hydrogen- and alkali-metal-vacancy complexes in silicon

1984 ◽  
Vol 29 (4) ◽  
pp. 1819-1823 ◽  
Author(s):  
Gary G. DeLeo ◽  
W. Beall Fowler ◽  
George D. Watkins
Keyword(s):  
Electronic Structure ◽  
Alkali Metal ◽  
Metal Vacancy

The Atomic Structure of the UO2 (111) Surface and the Effects of Additional Surface Oxygen Studied by Elevated Temperature STM

1998 ◽  
Vol 05 (01) ◽  
pp. 315-320 ◽  
Author(s):  
C. Muggelberg ◽  
M. R. Castell ◽  
G. A. D. Briggs ◽  
D. T. Goddard
Keyword(s):  
Elevated Temperature ◽  
Atomic Structure ◽  
Uranium Oxide ◽  
The Other ◽  
Surface Oxygen ◽  
Surface Termination ◽  
Sample Bias ◽  
Different Types ◽  
Stm Images ◽  
Mobile Oxygen

The structure of the UO 2+x (111) surface has been investigated by elevated temperature STM. Images of atomic terraces reveal two different types of surface termination. One of them corresponds to the stoichiometric UO 2 (111) surface and can be resolved atomically in empty state images above ~ 1.6 V sample bias. The observed (1 × 1) ordering is thought to be due to uranium states because its occurrence corresponds to the bottom of the empty uranium 5f band. On these terraces mobile oxygen forms a local [Formula: see text] superstructure. The other terrace type observed on top of the UO 2+x (111) surface is thought to be a phase of a higher uranium oxide which has grown epitaxially.

How “Native” Are Heritage Speakers?

2013 ◽  
Vol 10 (2) ◽  
pp. 153-177 ◽  
Author(s):  
Silvina Montrul
Keyword(s):  
Language Learning ◽  
Experimental Evidence ◽  
Native Speakers ◽  
Learning Experience ◽  
Age Of Acquisition ◽  
The Other ◽  
Gender Agreement ◽  
Heritage Speakers ◽  
High Incidence ◽  
Incomplete Acquisition

One of the chief characteristics of heritage speakers is that they range in proficiency from “overhearers” to “native” speakers. To date, the vast majority of linguistic and psycholinguistic studies have characterized the non-target-like linguistic abilities of heritage speakers as a product of incomplete acquisition and/or attrition due to reduced exposure and opportunities to use the language during childhood. This article focuses on the other side of the problem, emphasizing instead the high incidence of native-like abilities in adult heritage speakers. I illustrate this issue with recent experimental evidence from gender agreement in Spanish, a grammatical feature that is mastered at almost 100% accuracy in production by native speakers;yet it is one of the most difficult areas to master for non-native speakers, including near-natives.I discuss how age of acquisition and language-learning experience explain these effects.

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