scholarly journals Physical properties of iodate solutions and the deliquescence of crystalline I<sub>2</sub>O<sub>5</sub> and HIO<sub>3</sub>

2010 ◽  
Vol 10 (24) ◽  
pp. 12251-12260 ◽  
Author(s):  
R. Kumar ◽  
R. W. Saunders ◽  
A. S. Mahajan ◽  
J. M.C. Plane ◽  
B. J. Murray
Keyword(s):  
Water Activity ◽  
Temperature Dependent ◽  
Activity Data ◽  
Gas Phase Chemistry ◽  
Activity Density ◽  
Phase Chemistry ◽  
First Time ◽  
Measured Water ◽  
Complex Ion

Abstract. Secondary aerosol produced from marine biogenic sources in algal-rich coastal locations will initially be composed of iodine oxide species, most likely I2O5, or its hydrated form HIO3, formed as a result of iodine gas-phase chemistry. At present, there is no quantitative hygroscopic data for these compounds and very little data available for iodate solutions (HIO3 and I2O5 share a common aqueous phase). With increased interest in the role of such aerosol in the marine atmosphere, we have conducted studies of (i) the deliquescence behaviour of crystalline HIO3 and I2O5 at 273–303 K, (ii) the efflorescence behaviour of aqueous iodate solution droplets, and (iii) properties (water activity, density, and viscosity) of subsaturated and saturated iodate solutions. The deliquescence of I2O5 crystals at 293 K was observed to occur at a relative humidity (DRH) of 80.8±1.0%, whereas for HIO3, a DRH of 85.0±1.0% was measured. These values are consistent with measured water activity values for saturated I2O5 and HIO3 solutions at 293 K of 0.80±0.01 and 0.84±0.01 respectively. At all temperatures, DRH values for HIO3 crystals were observed to be higher than for those of I2O5. The temperature-dependent DRH data, along with solubility and water activity data were used to evaluate the enthalpy of solution (ΔHsol) for HIO3 and I2O5. A ΔHsol value of 8.3±0.7 kJ mol−1 was determined for HIO3 which is consistent with a literature value of 8.8 kJ mol−1. For I2O5, we report for the first time its solubility at various temperatures and ΔHsol = 12.4±0.6 kJ mol−1. The measured water activity values confirm that aqueous iodate solutions are strongly non-ideal, consistent with previous reports of complex ion formation and molecular aggregation.

scholarly journals Physical properties of iodate solutions and the deliquescence of crystalline I<sub>2</sub>O<sub>5</sub> and HIO<sub>3</sub>

2010 ◽  
Vol 10 (9) ◽  
pp. 20823-20856 ◽  
Author(s):  
R. Kumar ◽  
R. W. Saunders ◽  
A. S. Mahajan ◽  
J. M. C. Plane ◽  
B. J. Murray
Keyword(s):  
Water Activity ◽  
Temperature Dependent ◽  
Activity Data ◽  
Gas Phase Chemistry ◽  
Activity Density ◽  
Phase Chemistry ◽  
First Time ◽  
Measured Water ◽  
Complex Ion

Abstract. Secondary aerosol produced from marine biogenic sources in algal-rich coastal locations will initially be composed of iodine oxide species, most likely I2O5, or its hydrated form HIO3, formed as a result of iodine gas-phase chemistry. At present, there is no quantitative hygroscopic data for these compounds and very little data available for iodate solutions (HIO3 and I2O5 share a common aqueous phase). With increased interest in the role of such aerosol in the marine atmosphere, we have conducted studies of (i) the deliquescence behaviour of crystalline HIO3 and I2O5 at 273–303 K, (ii) the efflorescence behaviour of aqueous iodate solution droplets, and (iii) properties (water activity, density, and viscosity) of subsaturated and saturated iodate solutions. The deliquescence of I2O5 crystals at 293 K was observed to occur at a relative humidity (DRH) of 80.8±1.0%, whereas for HIO3, a DRH of 85.0±1.0% was measured. These values are consistent with measured water activity values for saturated I2O5 and HIO3 solutions at 293 K of 0.80±0.01 and 0.84±0.01 respectively. At all temperatures, DRH values for HIO3 crystals were observed to be higher than for those of I2O5. The temperature-dependent DRH data, along with solubility and water activity data were used to evaluate the enthalpy of solution (ΔHsol) for HIO3 and I2O5. A (ΔHsol value of 8.3±0.7 kJ mol−1 was determined for HIO3 which is consistent with a literature value of 8.8 kJ mol−1. For I2O5, we report for the first time its solubility at various temperatures and (ΔHsol=12.4±.6 kJ mol−1. The measured water activity values confirm that aqueous iodate solutions are strongly non-ideal, consistent with previous reports of complex ion formation and molecular aggregation.

Direct Synthesis of Silicon Nanowires using Silane and Molten Gallium

2002 ◽  
Vol 737 ◽  
Author(s):  
Shashank Sharma ◽  
Mahendra K. Sunkara ◽  
Elizabeth C. Dickey
Keyword(s):  
Silicon Nanowires ◽  
Crystalline Silicon ◽  
Direct Synthesis ◽  
Growth Direction ◽  
Single Crystalline ◽  
Gas Phase Chemistry ◽  
Transmission Electron ◽  
Phase Chemistry ◽  
First Time ◽  
Low Solubility

ABSTRACTWe report for the first time, bulk synthesis of single crystalline silicon nanowires using molten gallium pools and an activated vapor phase containing silane. The resulting silicon nanowires were single crystalline with <100> growth direction. Nanowires contained an unexpectedly thin, non-uniform oxide sheath determined using high-resolution Transmission Electron Microscopy (TEM). Nanowires were tens of nanometers in diameter and tens to hundreds of microns long. The use of activated gas phase chemistry containing solute of interest over molten metal pools of low-solubility eutectics such as gallium offer a viable route to generate nanowire systems containing abrupt compositional hetero-interfaces.

Polyamine ligands. I. The stereochemistry of transition metal complexes with the ligand 1,8-Bis(2'-pyridyl)-3,6-diazaoctane

1970 ◽  
Vol 23 (3) ◽  
pp. 491 ◽  
Author(s):  
AT Phillip ◽  
AT Casey ◽  
CR Thompson
Keyword(s):  
Transition Metal Complexes ◽  
Metal Ion ◽  
Electronic Absorption Spectra ◽  
Magnetic Moments ◽  
Temperature Dependent ◽  
Physical Measurements ◽  
Square Planar ◽  
First Time ◽  
Perchlorate Complex ◽  
Complex Ion

The new polyamine ligand 1,8-bis(2'-pyridyl)-3,6-diazaoctane has been synthesized for the first time by the reaction between 2-vinylpyridine and ethyl-enediamine. The ligand could not be distilled without decomposition and hence it was purified by converting it into the crystalline copper(11) perchlorate complex, from which the ligand was liberated by the reaction with sodium sulphide solution. The pure ligand was obtained in an overall yield of 28%, based on starting materials. The complexes formed by the ligand with the metal ions copper(11), nicke1(11), palladium(11), zinc(11), and cobalt(111) were isolated and characterized by physical measurements of their conductance in solution, magnetic moments, infrared and electronic absorption spectra. The ligand adopts the planar-N4 configuration around the metal ion in the complexes with copper(11), nicke1(11), and palladiurn(11), whereas it probably adopt's a tetrahedral-N4 configuration around the zinc(11) complex ion. The nickel(11) perchlorate complex is diamagnetic in the solid state and it most likely contains the metal ion in square-planar cordination. When dissolved in coordinating solvents, this complex undergoes a reversible, temperature-dependent equilibrium between diamagnetic and solvated, paramagnetic forms.

scholarly journals On the role of monoterpene chemistry in the remote continental boundary layer

2013 ◽  
Vol 13 (8) ◽  
pp. 22297-22335
Author(s):  
E. C. Browne ◽  
P. J. Wooldridge ◽  
K.-E. Min ◽  
R. C. Cohen
Keyword(s):  
Boreal Forest ◽  
Transport Model ◽  
Ozone Production ◽  
Organic Nitrate ◽  
Organic Nitrates ◽  
Chemical Transport Model ◽  
Gas Phase Chemistry ◽  
Rural Environments ◽  
Phase Chemistry

Abstract. The formation of organic nitrates (RONO2) represents an important NOx (NOx = NO + NO2) sink in remote and rural continental atmosphere thus impacting ozone production and secondary organic aerosol (SOA) formation. In these remote and rural environments, the organic nitrates are primarily derived from biogenic volatile organic compounds (BVOCs) such as isoprene and monoterpenes. Although there are numerous studies investigating the formation of SOA from monoterpenes, there are few studies investigating monoterpene gas phase chemistry. Using a regional chemical transport model with an extended representation of organic nitrate chemistry we investigate the processes controlling the production and fate of monoterpene nitrates (MTNs) over the boreal forest of Canada. MTNs account for 5–12% of total oxidized nitrogen over the boreal forest and production via NO3 chemistry is more important than production via OH when the NOx mixing ratio is greater than 75 pptv. The regional responses are investigated for two oxidation pathways of MTNs: one that returns NOx to the atmosphere and one that converts MTNs to a nitrate that behaves like HNO3. The likely situation is in between and these two assumptions bracket the uncertainty about this chemistry. In the case where the MTNs return NOx after oxidation, their formation represents a net chemical NOx loss that exceeds the net loss to peroxy nitrate formation. When oxidation of MTNs produces a molecule that behaves like HNO3, HNO3 and MTNs are nearly equal chemical sinks for NOx. This uncertainty in the oxidative fate of MTNs results in changes in NOx of 8–14%, in O3 of up to 3%, and in OH of 3–6% between the two model simulations.

scholarly journals Detection of Deuterated Formaldehyde in Interstellar Clouds

1980 ◽  
Vol 87 ◽  
pp. 439-443
Author(s):  
William D. Langer ◽  
Margaret A. Frerking ◽  
Richard A. Linke ◽  
Robert W. Wilson
Keyword(s):  
Gas Phase ◽  
Interstellar Clouds ◽  
Gas Phase Chemistry ◽  
Phase Chemistry ◽  
First Time

AbstractDeuterated formaldehyde has been detected for the first time in interstellar clouds; the observed ratio HDCO/H2CO implies formation by gas phase chemistry.

scholarly journals On the role of monoterpene chemistry in the remote continental boundary layer

2014 ◽  
Vol 14 (3) ◽  
pp. 1225-1238 ◽  
Author(s):  
E. C. Browne ◽  
P. J. Wooldridge ◽  
K.-E. Min ◽  
R. C. Cohen
Keyword(s):  
Boreal Forest ◽  
Transport Model ◽  
Ozone Production ◽  
Organic Nitrate ◽  
Organic Nitrates ◽  
Chemical Transport Model ◽  
Gas Phase Chemistry ◽  
Rural Environments ◽  
Phase Chemistry

Abstract. The formation of organic nitrates (RONO2) represents an important NOx (NOx = NO + NO2) sink in the remote and rural continental atmosphere, thus impacting ozone production and secondary organic aerosol (SOA) formation. In these remote and rural environments, the organic nitrates are primarily derived from biogenic volatile organic compounds (BVOCs) such as isoprene and monoterpenes. Although there are numerous studies investigating the formation of SOA from monoterpenes, there are few studies investigating monoterpene gas-phase chemistry. Using a regional chemical transport model with an extended representation of organic nitrate chemistry, we investigate the processes controlling the production and fate of monoterpene nitrates (MTNs) over the boreal forest of Canada. MTNs account for 5–12% of total oxidized nitrogen over the boreal forest, and production via NO3 chemistry is more important than production via OH when the NOx mixing ratio is greater than 75 pptv. The regional responses are investigated for two oxidation pathways of MTNs: one that returns NOx to the atmosphere and one that converts MTNs into a nitrate that behaves like HNO3. The likely situation is in between, and these two assumptions bracket the uncertainty about this chemistry. In the case where the MTNs return NOx after oxidation, their formation represents a net chemical NOx loss that exceeds the net loss to peroxy nitrate formation. When oxidation of MTNs produces a molecule that behaves like HNO3, HNO3 and MTNs are nearly equal chemical sinks for NOx. This uncertainty in the oxidative fate of MTNs results in changes in NOx of 8–14%, in O3 of up to 3%, and in OH of 3–6% between the two model simulations.

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