Amorphous carbon film deposition on inner surface of tubes using atmospheric pressure pulsed filamentary plasma source

Uniform amorphous carbon film is deposited on the inner surface of quartz tube having the inner diameter of 6 mm and the outer diameter of 8 mm. A pulsed filamentary plasma source is used for the deposition. Long plasma filaments (~ 140 mm) as a positive discharge are generated inside the tube in argon with methane admixture. FTIR-ATR, XRD, SEM, LSM and XPS analyses give the conclusion that deposited film is amorphous composed of non-hydrogenated sp2 carbon and hydrogenated sp3 carbon. Plasma is characterized using optical emission spectroscopy, voltage-current measurement, microphotography and numerical simulation. On the basis of observed plasma parameters, the kinetics of the film deposition process is discussed

Experimental and computational investigations of electron dynamics in micro atmospheric pressure radio-frequency plasma jets operated in He/N2 mixtures

The electron power absorption dynamics in radio frequency driven micro atmospheric pressure capacitive plasma jets are studied based on experimental phase resolved optical emission spectroscopy and the computational particle in cell simulations with Monte Carlo treatment of collisions. The jet is operated at 13.56 MHz in He with different admixture concentrations of N2 and at several driving voltage amplitudes. We find the spatio-temporal dynamics of the light emission of the plasma at various wavelengths to be markedly different. This is understood by revealing the population dynamics of the upper levels of selected emission lines/bands based on comparisons between experimental and simulation results. The populations of these excited states are sensitive to different parts of the electron energy distribution function and to contributions from other excited states. Mode transitions of the electron power absorption dynamics from the Ω- to the Penning-mode are found to be induced by changing the N2 admixture concentration and the driving voltage amplitude. Our numerical simulations reveal details of this mode transition and provide novel insights into the operation details of the Penning-mode. The characteristic excitation/emission maximum at the time of maximum sheath voltage at each electrode is found to be based on two mechanisms: (i) a direct channel, i.e. excitation/emission caused by electrons generated by Penning ionization inside the sheaths and (ii) an indirect channel, i.e. secondary electrons emitted from the electrode due to the impact of positive ions generated by Penning ionization at the electrodes

Synthesis, spectral characterization and crystal structures of organophosphonic diamides: pyramidal nitrogen centers and hydrogen bonding in [PhP(O)((NHBu)-Bu-t)(2)], [PhP( O)(NHDipp)(2)](Dipp=2,6-(Pr2C6H3)-Pr-i) and [(BuP)-Bu-t(O)((NHPr)-Pr-i)(2)]

Organophosphonic diamides of general formula [(RP)-P-1(O)(NHR2)(2)] (1-8; R-1=Ph, Cy or Bu-t and R-2=Cy, Pr-i, Bu-t or Dipp) have been prepared by the addition of P, P'-dichloro(alkyl/aryl)phosphine oxide, (RP)-P-1(O)Cl-2, to a solution of primary amine in toluene. The synthesis of PhP(O)((NHBu)-Bu-t)(2) (1) in high yield was achieved by slow oxidation of PhP((NHBu)-Bu-t)(2) in air over several days. All new compounds have been characterized by elemental analysis and by IR, EI mass and NMR (H-1 and P-31) spectroscopy. The molecular structures of [PhP(O)((NHBu)-Bu-t)(2)] (1), [PhPO(NHDipp)(2)] (2) and [(BuP)-Bu-t(O)((NHPr)-Pr-i)(2)] (7) have been determined by single crystal X-ray diffraction studies. The amido nitrogen atoms in 1, 2 and 7 show considerable deviation from the expected trigonal-planar geometry. The observed dihedral angles and the orientation of the nitrogen lone pair ( l. p.) in these compounds point to the role of l.p.(N)-->sigma*(P-X) type negative hyperconjugative interactions in P-N multiple bonding. Compounds 1 and 7 form interesting polymeric structures in the solid state with the aid of N-H...O=P hydrogen bonding interactions while the presence of the very bulky Dipp substituent on nitrogen in 2 prevents the participation of the N-H protons in hydrogen bonding with phosphoryl oxygen atoms

Copper phosphates and phosphinates with pyridine/pyrazole alcohol co-ligands: Synthesis and structure

Copper phosphates, [Cu(dtbp)(2)(pzet)(2)]center dot H(2)O (1) and [Cu(dtbp)(2)(pyme)(2)] (2), as well as copper phosphinate, [Cu(dppi)(2)(pyet)(2)] (3) have been synthesized by the reaction of copper acetate with di-tert-butyl phosphate (dtbp) or diphenyl phosphinate (dppi) in the presence of pyridine base having hydroxyl group, namely, 3,5-dimethylpyrazole-2-ethanol (pzet) or 2-(hydroxymethyl) pyridine (pyme) or 2-(2-hydroxyethyl) pyridine (pyet). Single crystal X-ray diffraction studies reveal that copper ion in all the three complexes is bonded to two phosphoryl ions (P(O)O ) and two pyridine co-ligands. The crystal structure of 1 reveals that the hydroxyl group of the CH(2)CH(2)OH moiety of pzet ligand exhibits a positional disorder between the non-bonding position and the bonding position with respect to the central copper ion along the Jahn-Teller axis. Hence, the structure of 1 can be considered to exhibit both 'square-planar' and 'octahedral' coordination geometries simultaneously for the copper ion in the same complex. A similar situation for the -OH groups has not been observed in the complexes 2 and 3 and hence the coordination geometry around the copper ion is axially elongated octahedron. (C) 2011 Elsevier B.V. All rights reserved

Cobalt and manganese nets via their wires: Facile transformation in metal-diorganophosphates

The manganese and cobalt complexes [M(dtbP)(2)](n) (M = Mn, Co; dtbp = di-tert-butyl phosphate), which exist as one-dimensional molecular wires, transform to [M(dtbP)(2)(bpy)(2)(.)2H(2)O](n) by the addition of 4,4-bipyridine (bpy) at room temperature; the latter compounds form noninterpenetrating rectangular grid structures

Non-interpenetrating transition metal diorganophosphate 2-dimensional rectangular grids from their 1-dimensional wires: structural, transformations under mild conditions

The manganese, cobalt, and cadmium complexes [M(dtbP)(2)](n) (M = Mn (1) and Cc (2)) and [Cd(dtbP)(2)(H2O)](n), (3) (dtbp = di-tert-butyl phosphate), which exist as one-dimensional molecular wires, transform to non-interpenetrating rectangular grids [M(dtbP)(2)(bPY)(2)(.)2H(2)O](n) (M = Mn (4), Co (5), and Cd (6)) by the addition of 4,4-bipyridine (bpy) at room temperature. Products 4-6 have also been prepared by a room-temperature reaction or by solvothermal synthesis in methanol through a direct reaction between the metal acetate, di-tert-butyl phosphate, and 4,4 '-bipyridine (bpy) in a 1:22 molar ratio. Single-crystal X-ray structure determination of 4-6 shows that these compounds are composed of octahedral transition metal ions woven into a two-dimensional grid structure with the help of bpy spacer ligands. The axial coordination sites at the metal are occupied by bulky unidentate dtbp ligands, which prevent any interpenetration of the individual grids. The change of reaction conditions from solvothermal to hydrothermal, for the attempted synthesis of a magnesium grid structure, however leads to the isolation of an organic phosphate [(H(2)bpy)(H2PO4)(2)] (7) and an inorganic phosphate [Mg(HPO4)(OH2)(3)] (8). Compound 7 can also be prepared quantitatively from a direct reaction between bpy and H3PO4. The new organic phosphate 7 is a unique example of a phosphate material with alternating layers of [H(2)bpy](2+) cations and [H2PO4](2+) anions that are held together by hydrogen bonds. Solid-state thermal decomposition of 4-6 produced the respective metaphosphate materials [M(PO3)(2)] (M = Mn (9), Cc (10), and Cd (11)). All new metal-organic phosphates have been characterized by elemental analysis, thermal analysis (TGA, DTA, DSC), and IR and NMR spectroscopy. The metaphosphate ceramic materials were characterized by IR spectral and powder X-ray diffraction studies

Reactions of [(Me(3)Si)(3)CAlMe(2)] with substituted benzoic acids. Isolation of a rare organoalumoxane carboxylate

The reactivity of bulky tris(trimethylsilyl) methyl group substituted aluminum trialkyl [(Me(3)Si)(3)CAlMe(2)center dot THF] (1) with a series of substituted benzoic acid derivatives has been investigated. An equimolar reaction of 4-methyl benzoic acid or 4-tert-butyl benzoic acid with 1 in toluene at 50 degrees C leads to the formation of cyclic dimeric aluminum carboxylates [(Me(3)Si)(3)CAl(Me)(mu-O(2)CC(6)H(4)R)](2) (R = Me 2; (t)Bu 3). Reaction of 3,5-di-iso- propylsalicylic acid (H(2)dipsa) with 1 leads to the exclusive isolation of a trimeric organoaluminum carboxylate [(Me(3)Si)(3)CAl(mu-ipsa)](3) (4), in which each aluminum is bound to two carboxylates, a phenoxide, and an alkyl group and produce a 12-membered macrocycle. Deliberate, but controlled, introduction of water in the form of 3,5-di-tert-butyl salicylic acid monohydrate (H(2)dtbsa center dot H(2)O) in the reaction with 1 in toluene leads to the isolation of carboxylate [(Me(3)Si)(3)CAl(mu-O)(mu-Hdtbsa)}(2)] (5) with a bicyclic structure. Compound 5 represents a rare example of an organoalumoxane carboxylate that simultaneously possesses alkyl, oxo, and carboxylate moieties on aluminum. (C) 2011 Elsevier B.V. All rights reserved

Monomeric, tetrameric, and polymeric copper di-tert-butyl phosphate complexes containing pyridine ancillary ligands

The reaction of di-tert-butyl phosphate (((BuO)-Bu-t)(2)P(O)(OH), dtbp-H) with copper acetate in the presence of pyridine (py) and 2,4,6-trimethylpyridine (collidine) has been investigated. Copper acetate reacts with dtbp-H in a reaction medium containing pyridine, DOC, THF, and CH3OH to yield a one-dimensional polymeric complex [Cu(dtbP)(2)(py)(2)(mu-OH2)](n) (1) as blue hollow crystalline tubes. The copper atoms in 1 are octahedral and are surrounded by two terminal phosphate ligands, two pyridine molecules, and two bridging water molecules. The mu-OH2 ligands that are present along the elongated Jahn-Teller axis are responsible for the formation of the one-dimensional polymeric structure. Recrystallization of 1 in a DMSO/THF/CH3OH mixture results in the reorganization of the polymer and its conversion to a more stable tetranuclear copper cluster [Cu-4(mu(3)-OH)(2)(dtbP)(6)(py)(2)] (2) in about 60% yield. The molecular structure of 2 is made up of a tetranuclear core [Cu-4(mu(3)-OH)(2)] which is surrounded by six bidentate bridging dtbp ligands. While two of the copper atoms are pentacoordinate with a tbp geometry, the other two copper atoms exhibit a pseudooctahedral geometry with five normal Cu-O bonds and an elongated Cu-O linkage. The pentacoordinate copper centers bear an axial. pyridine ligand. The short Cu...Cu nonbonded distances in the tetranuclear core of 2 lead to magnetic ordering at low temperature with an antiferromagnetic coupling at similar to20 K (J(p) = -44 cm(-1), J(c) = -66 cm(-1), g = 2.25, and p = 0.8%). When the reaction between di-tert-butyl phosphate (dtbp-H) and copper acetate was carried out in the presence of collidine, large dark-blue crystals of monomeric copper complex [Cu(dtbP)(2)(collidine)(2)] (3) formed as the only product. A single-crystal X-ray diffraction study of 3 reveals a slightly distorted square-planar geometry around the copper atom. Thermogravimetric analysis of 1-3 revealed a facile decomposition of the coordinated ligands and dtbp to produce a copper phosphate material around 500 degreesC. An independent solid-state thermolysis of all the three complexes in bulk at 500-510 degreesC for 2 days produced copper pyrophosphate Cu2P2O7 along with small quantities of Cu(PO3)(2) as revealed by DR-UV spectroscopic and PXRD studies

Structural diversity in zinc phosphates and phosphinates: Observation of a lattice water dimer sandwiched between phosphoryl oxygen atoms

Reactions of zinc acetate dihydrate with organic phosphates [(RO)(2)P(O)(OH)] (R = tBu, Ph) and phosphinic acids [PhR'P(O)(OH)] (R' = Ph, H) have been investigated in the presence of 1,10-phenanthroline (phen). While the use of ditert-butyl phosphate (dtbp-H) results in the formation of [Zn(phen)(2)(dtbp)(OH2)][dtbp](MeOH)(MeCOOH)(H2O)(3) (1), the change of phosphorus source to diphenylphosphate (dppH) yields an interesting phosphate-bridged dinuclear complex [{Zn(phen)(dpp)}(2){mu(2)-dpp)(2)] (2). Mononuclear complexes [Zn(phen)(2)(dppi)(2)](H2O)(2) (3) and [Zn(phen)(2)(ppi)(2)](H2O) (4) have been obtained from similar reactions by the use of diphenylphosphinic acid (dppi-H) and phenylphosphinic acid (ppi-H), respectively. The high steric bulk of the dtbp ligand results in the formation of the cationic complex 1, where only one of the dtbp ligands is directly coordinated to the metal atom, leaving the second dtbp molecule as the counter anion. The inorganic core of dinuclear zinc phosphate 2 resembles the single four-ring (S4R) secondary building unit of framework zinc phosphates. Compounds 3 and 4 are neutral monomeric hexacoordinate complexes with two chelating 1,10-phen ligands and two monodentate phosphinate ligands. The two lattice water molecules in 3 form an interesting water dimer (H2O)(2). These water dimers link the mononuclear zinc complexes in the lattice to form an H-bonded one-dimensional polymer. Similarly, the lattice water present in 4 serves to link the zinc phenylphosphinate molecules through hydrogen bonding in the form of a 1-D polymer. The reaction of the precursor complex [Zn(bPY)(2)(OAc)](ClO4)center dot H2O with dpp-H, dppi-H, and ppi-H in methanol leads to the formation of zinc phosphate [Zn(bpy)(2)(dpp)](2)(ClO4)(2)center dot H2O (5) and phosphinates [Zn(bpy)(2)(dppi)](2)(ClO4)(2) (6) and [Zn(bpy)(2)(ppi)](2)(ClO4)(2) (7), respectively. The molecular structures of 1-5 and 7 have been determined by single-crystal X-ray diffraction studies. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)