Three Distinct Torsion Profiles of Electronic Transmission Through Linear Carbon Wires

2020 ◽  
Author(s):  
Marc Hamilton Garner ◽  
William Bro-Jørgensen ◽  
Gemma C. Solomon
Keyword(s):  
Linear Chain ◽  
Type Systems ◽  
Closed Shell ◽  
Molecular Forms ◽  
Carbon Allotrope ◽  
Axial Torsion ◽  
End Groups ◽  
Structural Nature ◽  
Electron Transport Properties ◽  
The One

<p>The one-dimensional carbon allotrope carbyne, a linear chain of <i>sp</i>-hybridized carbon atoms, is predicted to exist in a polyynic and a cumulenic structure. While molecular forms of carbyne have been extensively characterized, the structural nature is hard to determine for many linear carbon wires that are made in-situ during pulling experiments. Here, we show that cumulenes and polyynes have distinctively different low-bias conductance profiles under axial torsion. We analyze the change of the electronic structure, Landauer transmission, and ballistic current density of the three types of closed-shell molecular carbynes as a function of the torsion angle. Both polyynic, odd-carbon cumulenic,<i> </i>and even-carbon cumulenic carbon wires exhibit helical frontier molecular orbitals when the end-groups are not in a co-planar configuration. This helical conjugation effect gives rise to strong ring current patterns around the linear wires. Only the transmission of even-carbon polyynic wires follows the well-known cosine-squared law with axial torsion that is also seen in biphenyl-type systems. Notably, the transmission of even-carbon cumulenic carbon wires rises with axial torsion from co-planar towards perpendicular orientation of the end-groups. The three distinct transmission profiles of polyynes, odd-carbon cumulenes,<i> </i>and even-carbon cumulenes may allow for experimental identification of the structural nature of linear carbon wires. Their different electron transport properties under axial torsion furthermore underline that, in the molecular limit of carbyne, three different subclasses of linear carbon wires exist.</p>

scholarly journals Three Distinct Torsion Profiles of Electronic Transmission Through Linear Carbon Wires

2020 ◽  
Author(s):  
Marc Hamilton Garner ◽  
William Bro-Jørgensen ◽  
Gemma C. Solomon
Keyword(s):  
Linear Chain ◽  
Type Systems ◽  
Closed Shell ◽  
Molecular Forms ◽  
Carbon Allotrope ◽  
Axial Torsion ◽  
End Groups ◽  
Structural Nature ◽  
Electron Transport Properties ◽  
The One

<p>The one-dimensional carbon allotrope carbyne, a linear chain of <i>sp</i>-hybridized carbon atoms, is predicted to exist in a polyynic and a cumulenic structure. While molecular forms of carbyne have been extensively characterized, the structural nature is hard to determine for many linear carbon wires that are made in-situ during pulling experiments. Here, we show that cumulenes and polyynes have distinctively different low-bias conductance profiles under axial torsion. We analyze the change of the electronic structure, Landauer transmission, and ballistic current density of the three types of closed-shell molecular carbynes as a function of the torsion angle. Both polyynic, odd-carbon cumulenic,<i> </i>and even-carbon cumulenic carbon wires exhibit helical frontier molecular orbitals when the end-groups are not in a co-planar configuration. This helical conjugation effect gives rise to strong ring current patterns around the linear wires. Only the transmission of even-carbon polyynic wires follows the well-known cosine-squared law with axial torsion that is also seen in biphenyl-type systems. Notably, the transmission of even-carbon cumulenic carbon wires rises with axial torsion from co-planar towards perpendicular orientation of the end-groups. The three distinct transmission profiles of polyynes, odd-carbon cumulenes,<i> </i>and even-carbon cumulenes may allow for experimental identification of the structural nature of linear carbon wires. Their different electron transport properties under axial torsion furthermore underline that, in the molecular limit of carbyne, three different subclasses of linear carbon wires exist.</p>

scholarly journals Three Distinct Torsion Profiles of Electronic Transmission Through Linear Carbon Wires

2020 ◽  
Author(s):  
Marc Hamilton Garner ◽  
William Bro-Jørgensen ◽  
Gemma C. Solomon
Keyword(s):  
Linear Chain ◽  
Type Systems ◽  
Closed Shell ◽  
Molecular Forms ◽  
Carbon Allotrope ◽  
Axial Torsion ◽  
End Groups ◽  
Structural Nature ◽  
Electron Transport Properties ◽  
The One

<p>The one-dimensional carbon allotrope carbyne, a linear chain of <i>sp</i>-hybridized carbon atoms, is predicted to exist in a polyynic and a cumulenic structure. While molecular forms of carbyne have been extensively characterized, the structural nature is hard to determine for many linear carbon wires that are made in-situ during pulling experiments. Here, we show that cumulenes and polyynes have distinctively different low-bias conductance profiles under axial torsion. We analyze the change of the electronic structure, Landauer transmission, and ballistic current density of the three types of closed-shell molecular carbynes as a function of the torsion angle. Both polyynic, odd-carbon cumulenic,<i> </i>and even-carbon cumulenic carbon wires exhibit helical frontier molecular orbitals when the end-groups are not in a co-planar configuration. This helical conjugation effect gives rise to strong ring current patterns around the linear wires. Only the transmission of even-carbon polyynic wires follows the well-known cosine-squared law with axial torsion that is also seen in biphenyl-type systems. Notably, the transmission of even-carbon cumulenic carbon wires rises with axial torsion from co-planar towards perpendicular orientation of the end-groups. The three distinct transmission profiles of polyynes, odd-carbon cumulenes,<i> </i>and even-carbon cumulenes may allow for experimental identification of the structural nature of linear carbon wires. Their different electron transport properties under axial torsion furthermore underline that, in the molecular limit of carbyne, three different subclasses of linear carbon wires exist.</p>

scholarly journals Three Distinct Torsion Profiles of Electronic Transmission Through Linear Carbon Wires

2020 ◽  
Author(s):  
Marc Hamilton Garner ◽  
William Bro-Jørgensen ◽  
Gemma C. Solomon
Keyword(s):  
Linear Chain ◽  
Type Systems ◽  
Closed Shell ◽  
Molecular Forms ◽  
Carbon Allotrope ◽  
Axial Torsion ◽  
End Groups ◽  
Structural Nature ◽  
Electron Transport Properties ◽  
The One

<p>The one-dimensional carbon allotrope carbyne, a linear chain of <i>sp</i>-hybridized carbon atoms, is predicted to exist in a polyynic and a cumulenic structure. While molecular forms of carbyne have been extensively characterized, the structural nature is hard to determine for many linear carbon wires that are made in-situ during pulling experiments. Here, we show that cumulenes and polyynes have distinctively different low-bias conductance profiles under axial torsion. We analyze the change of the electronic structure, Landauer transmission, and ballistic current density of the three types of closed-shell molecular carbynes as a function of the torsion angle. Both polyynic, odd-carbon cumulenic,<i> </i>and even-carbon cumulenic carbon wires exhibit helical frontier molecular orbitals when the end-groups are not in a co-planar configuration. This helical conjugation effect gives rise to strong ring current patterns around the linear wires. Only the transmission of even-carbon polyynic wires follows the well-known cosine-squared law with axial torsion that is also seen in biphenyl-type systems. Notably, the transmission of even-carbon cumulenic carbon wires rises with axial torsion from co-planar towards perpendicular orientation of the end-groups. The three distinct transmission profiles of polyynes, odd-carbon cumulenes,<i> </i>and even-carbon cumulenes may allow for experimental identification of the structural nature of linear carbon wires. Their different electron transport properties under axial torsion furthermore underline that, in the molecular limit of carbyne, three different subclasses of linear carbon wires exist.</p>

Energy Recovery Methods in Adsorption Refrigeration Units

2017 ◽  
Author(s):  
Andrzej Grzebielec ◽  
Adam Szelągowski ◽  
Adam Ruciński
Keyword(s):  
Energy Loss ◽  
Thermal Wave ◽  
Energy Recovery ◽  
Type Systems ◽  
Adsorption Refrigeration ◽  
Wave Type ◽  
Recovery Processes ◽  
Refrigeration Unit ◽  
The One ◽  
Heat And Mass Recovery

Adsorption refrigeration systems, as opposed to absorption type operate in a cyclic manner. The result is that at the beginning of each process must be fed into the adsorber state in which they will adsorb or desorb a refrigerant. In the case of two adsorbers at the start of a cycle, the one of the adsorber must be refrigerated while the second has to be heated. These processes are causing unnecessary energy loss. The aim of the work is to show how these processes can be connected and the heat received from one adsorber is transported to another adsorber. As part of the study, the heat and mass recovery processes will be considered. It turns out that in the thermal wave type systems, it is possible to recover more than 25% of the energy lost to bring the adsorber to the states in which they will operate efficiently to desorb and adsorb refrigerant. That is, it is possible to improve the efficiency of the adsorption refrigeration unit using the proposed improvements.

On the Occurrence and Structure of Subunits of Endopolygalacturonase Isoforms in Mature-Green and Ripening Tomato Fruits

1991 ◽  
Vol 18 (1) ◽  
pp. 65 ◽  
Author(s):  
BJ Pogson ◽  
CJ Brady ◽  
GR Orr
Keyword(s):  
Tomato Fruit ◽  
Exchange Chromatography ◽  
Molecular Forms ◽  
Cation Exchange Chromatography ◽  
Ripe Fruit ◽  
Tomato Fruits ◽  
Green Fruit ◽  
C Terminus ◽  
The One ◽  
Polygalacturonase Activity

Endopolygalacturonase [poly(1,4-α-galacturonide) glycanohydrolase EC 3.2.1.151 occurs in tomato fruit in three molecular forms- PG1, PG2A, PG2B. Trace amounts of PG1, 1-10 pkat g-1 are shown to occur in mature-green fruit as compared to 17 nkat in ripe fruit. As polygalacturonase activity increases through ripening, the percentage of the activity due to PG1 decreases progressively from 100 to less than 20. On fully or partly demethylated substrates, PG1 is more active than PG2 when the ionic strength is that expected in the tissue apoplast. A method for purifying PGI from ripe fruit is described. PG1 preparations contain polypeptides of Mr 45, 43 and 38 thousand. The Mr 43 thousand and 45 thousand components correspond in size to PG2A and PG2B and are detected by antisera raised against PG2A. The M, 38 thousand polypeptide is immunologically distinct. From carbohydrate and amino acid analyses, this polypeptide appears to contain 2870 carbohydrate as glucosamine, mannose, xylose and fucose attached to a polypeptide of estimated Mr 28 342 that is rich in tyrosine and glycine. A method for purifying the subunits of PG1 by cation exchange chromatography in 6 M urea is described. PG2A and PG2B were separated by column chromatography and shown to have identical N-terminal sequences, and serine at the C-terminus. PG2A and PG2B are confirmed as two glycoforms of the one polypeptide. The possibility that PGl consists of populations of molecules containing either PG2A or PG2B coupled with the Mr 38 thousand polypeptide is discussed.

Electronic and Resonance Raman Spectra of Some New Mixed-Valence Compounds of Pt and Pd with a Metal-Halide Chain

1980 ◽  
Vol 35 (6) ◽  
pp. 676-679 ◽  
Author(s):  
G. C. Papavassiliou ◽  
D. Layek
Keyword(s):  
Raman Spectra ◽  
Linear Chain ◽  
Mixed Valence ◽  
Resonance Raman ◽  
Chain Structure ◽  
One Dimensional ◽  
Resonance Raman Spectra ◽  
The One ◽  
Mixed Valence Compounds ◽  
Linear Chain Structure

Abstract The electronic and resonance Raman spectra of new mixed-valence compounds of the type M2ʹ[M(L)X3][M(L)X5], where Mʹ = K, NH4, M = Pt or Pd, L = NH3 or pyridine, and X = Cl, Br or I, have been studied. The single-crystal polarized reflectance spectra indicate the one-dimensional semiconductor behaviour. The polarized resonance Raman spectra confirm the --M(II)--X-M(IV)-X linear chain structure, which is in accordance with the X-ray results. The polarization of M-N bands can be explained by the Snyder's theory (1971).

Non-Closed-Shell Linear Chain: TheH4nSystem

1968 ◽  
Vol 171 (2) ◽  
pp. 484-487 ◽  
Author(s):  
W. T. Kwo
Keyword(s):  
Linear Chain ◽  
Closed Shell

Misfit Dislocations

1977 ◽  
Vol 35 ◽  
pp. 120-123
Author(s):  
J. W. Matthews
Keyword(s):  
Simple Model ◽  
Linear Chain ◽  
Experimental System ◽  
Misfit Dislocations ◽  
Soap Bubbles ◽  
The One

In 1949 Frank and van der Merwe (1) considered the accommodation of misfit between one crystal and another using a simple model. The model consisted of a linear chain of atoms that was placed on a substrate in which there were sinusoidal corrugations. They showed that - in systems where the bonding between the atoms in the chain was comparable to the bonding of the atoms to their substrate - it was energetically favorable for a misfit of ≲ 7% to be accommodated by strain. An experimental system which resembles the one considered by Frank and van der Merwe, and is particularly well suited to test their predictions, is the bubble model of Bragg and Nye (2). Figure 1(a) shows a row of soap bubbles that is separated from a raft of bubbles by a barrier. The misfit between the row and raft is ∽7% . Figure 1(b) shows the bubbles after removal of the barrier. It can be seen that all the misfit is accommodated by strain.

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