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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

Antarctic ozone depletion chemistry - Reactions of N2O5 with H2O and HCl on ice surfaces

In a study concerning Antarctic ozone depletion, reactions of dinitrogen pentoxide with water and hydrochloric acid were studied on ice surfaces in a Knudsen cell flow reactor. The N2O5 reacted on ice at 185 K to form condensed-phase nitric acid (HNO3). This reaction may provide a sink for odd nitrogen, NO(x), during the polar winter, a requirement in nearly all models of Antarctic ozone depletion. The reaction of N2O5 on HCl-ice surfaces at 185 K produced gaseous nitryl chloride (ClNO2) and condensed-phase HNO3 and proceeded until all of the HCl within the ice was depleted. The ClNO2 which did not react or condense on ice at 185 K, can be readily photolyzed in the Antarctic spring to form atomic chlorine for catalytic ozone destruction cycles. The other photolysis product, gaseous nitrogen dioxide may be important in the partitioning of NO(x) between gaseous and condensed phases in the Antarctic winter.

Tolbert, Margaret A.↗
NASA NTRS1991

Role of heterogeneous conversion of N2O5 on sulphate aerosols in global ozone losses

The reaction rate of N2O5 on sulphate aerosols is included in a model to predict global ozone loss and the column abundances of atmospheric gases. Because the reaction of N2O5 and the aerosols can take place in the stratospheric sulphate aerosol layer, it is included in the 2D model so that the results can be compared to abundances derived from satellite data and ground-based measurements. The N2O5/sulphate reaction is the only heterogeneous reaction in the model, in which aerosol loading is assumed to be constant and only diurnal values are examined. The decadal ozone trends resulting from calculations based on the model are found to be closer to the observed values. An important conclusion is that measurements of OH, ClO, HNO3, NO, and NO2 in the region of about 14-25 km are needed to examine significant changes in their abundances resulting from the inclusion of the N2O5/sulphate aerosol reaction.

Rodriguez, Jose M.↗
NASA NTRS1994

Temperature dependent absorption cross-sections of HNO3 and N2O5

Absorption cross-sections for HNO3 and N2O5 have been measured in the wavelength region 220-450 nm, using a dual beam diode array spectrometer with a spectral resolution of 0.3 nm. The results for both compounds are in good agreement with recommended values at room temperature. However, the cross-sections of both HNO3 and N2O5 show a marked reduction with decreasing temperature in the range 295-233 K. The calculated photolysis rate of HNO3 at the low temperatures and high solar zenith angles characteristic of the polar winter and spring is significantly lower than previously estimated.

Rattigan, Oliver V.↗
DOE OSTI2020

Materials Data on N2O5 by Materials Project

N2O5 crystallizes in the hexagonal P6_3/mmc space group. The structure is zero-dimensional and consists of two hydroxylamine, n-hydroxy- molecules and two nitric acid molecules.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on MgCdH4(N2O5)2 by Materials Project

MgCdH4(N2O5)2 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Mg2+ is bonded in an octahedral geometry to six O2- atoms. There are two shorter (2.04 Å) and four longer (2.17 Å) Mg–O bond lengths. Cd2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Cd–O bond distances ranging from 2.42–2.59 Å. There are two inequivalent N3+ sites. In the first N3+ site, N3+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.26 Å) and one longer (1.28 Å) N–O bond length. In the second N3+ site, N3+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.26 Å) and one longer (1.28 Å) N–O bond length. There are two inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted water-like geometry to one Cd2+ and one N3+ atom. In the second O2- site, O2- is bonded in a 2-coordinate geometry to one Mg2+, one Cd2+, and one N3+ atom. In the third O2- site, O2- is bonded in a distorted water-like geometry to one Cd2+ and one N3+ atom. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to one Mg2+, one Cd2+, and one N3+ atom. In the fifth O2- site, O2- is bonded in a distorted water-like geometry to one Mg2+ and two H1+ atoms.

36 MATERIALS SCIENCE↗
NASA NTRS1988

Heterogeneous chemistry related to Antarctic ozone depletion: Reaction of ClONO2 and N2O5 on ice surfaces

Laboratory studies of heterogeneous reactions of possible importance for Antarctic ozone depletion were performed. In particular, the reactions of chlorine nitrate (ClONO2) and dinitrogen pentoxide (N2O5) were investigated on ice and HCl/ice surfaces. These reactions occur on the surfaces of polar stratospheric clouds (PSCs) over Antarctica. One reaction transforms the stable chlorine reservoir species (ClONO2 and HCl) into photochemically active chlorine in the form of HOCl and Cl2. Condensation of HNO3 in the reactions removes odd nitrogen from the stratosphere, a requirement in nearly all models of Antarctic ozone depletion. Other reactions may also be important for Antarctic ozone depletion. Like the reactions of chlorine nitrate, these reactions deplete odd nitrogen through HNO3 condensation. In addition, one reaction converts a stable chlorine reservior species (HCl) into photochemically active chlorine (ClNO2). These reactions were studied with a modified version of a Knudsen cell flow reactor.

Tolbert, Margaret A.↗
NASA NTRS1988

Mass accommodation coefficient measurements for HNO3, HCl and N2O5 on water, ice and aqueous sulfuric acid droplet surfaces

Preliminary results are reported of the direct measurement of accommodation coefficients for HNO3, N2O5 and HCl on water drops, aqueous sulfuric acid drops and ice particles. The heterogeneous chemistry of these species together with ClONO2 has been implicated in the ozone depletion observed in the Antarctic stratosphere during the spring in the last eight years. The most plausible chemical mechanism involves the removal of nitrogen oxide species via condensation on ice particles in polar stratospheric clouds resulting in a increase in the active chlorine species responsible for the ozone depletion. The observation of low NO2 and high ClO densities in the Antarctic stratosphere last summer appear to be consistent with such a mechanism.

Worsnop, Douglas↗
NASA NTRS1988

Measurement of nighttime stratospheric N2O5 from infrared emission spectra

The mixing ratio profile of N2O5 has been inferred from high-resolution emission spectra obtained with a balloon-borne Fourier spectrometer. The observations were taken for the period from midnight to predawn on September 16, 1986 at 32 deg N latitude. The inferred volume mixing ratio from nighttime average spectra has a peak of about 1.8 x 10 to the -9th in the 32-35 altitude range. The inferred mixing ratio is generally less than the theoretical predictions from a one-dimensional model.

Kunde, V. G.↗
NASA NTRS1988

High resolution, balloon-borne emission spectroscopy of trace species in the lower stratosphere - N2O5, HNO3

A liquid-nitrogen cooled Fourier transform spectrometer (SIRIS) measures thermal limb-emission of the stratosphere from a balloon platform at a nominal altitude of 40 km, under night and day conditions, with a 3 km vertical resolution. N2O5 and HNO3 mixing ratios inferred from emission spectra are compared with previous measurements and with the predictions from a one-dimensional photochemical model.

Brasunas, J.↗
NASA NTRS1994

Measurements of stratospheric NO, NO2, and N2O5 by ISAMS: Preliminary observations and data validation

The Improved Stratospheric and Mesospheric Sounder (ISAMS) is a multichannel radiometer and forms part of the science payload of the Upper Atmosphere Research Satellite (UARS). ISAMS measures infrared emissions from the Earth's atmosphere in several wavelength bands. Three such bands include emission from nitric oxide, nitrogen dioxide, and dinitrogen pentoxide. In this paper, we briefly discuss how the ISAMS instrument measures NO, NO2, and N2O5. We also present preliminary data from these channels and describe preliminary validation work.

Kerridge, Brian J.↗
NASA NTRS1994

Balloon profiles of stratospheric NO2 and HNO3 for testing the heterogeneous hydrolysis of N2O5 on sulfate aerosols

Simultaneous in situ measurements of stratospheric NO2, HNO3, HCl, and CH4 from 34 to 24 km were made in August 1992 from Palestine, Texas, using the Balloon-borne Laser In-Situ Sensor (BLISS) tunable diode laser spectrometer. Although the measurements of NO2, HNO3, and NO2/HNO3 agree well with gas-phase model calculations near 34 km where Stratospheric Aerosol and Gas Experiment (SAGE) 2 data show little sulfate aerosol, this is not true at the lower altitudes where SAGE 2 shows high aerosol loadings. At 24 km the BLISS NO2 and HNO3 measurements are 70% lower and 50% higher, respectively, than the gas phase model predictions, with a measured NO2/HNO3 ratio 5 times smaller. When the heterogeneous hydrolysis of N2O5 and ClONO2 on sulfate aerosol of surface area densities matching the SAGE 2 measurements is added to the model, good agreement with the BLISS measurements is found over the whole altitude range.

Webster, C. R.↗
NASA NTRS1994

The reaction probability of N2O5 with sulfuric acid aerosols at stratospheric temperatures and compositions

We have measured the rate of reaction of N2O5 with H2O on monodisperse, submicrometer H2SO4 particles in a low-temperature flow reactor. Measurements were carried out at temperatures between 225 K and 293 K on aerosol particles with sizes and compositions comparable to those found in the stratosphere. At 273 K, the reaction probability was found to be 0.103 +/- 0.0006, independent of H2SO4 composition from 64 to 81 wt%. At 230 K, the reaction probability increased from 0.077 for compositions near 60% H2SO4 to 0.146 for compositions near 70% H2SO4. Intermediate conditions gave intermediate results except for low reaction probabilities of about 0.045 at 260 K on aerosols with about 78% H2SO4. The reaction probability did not depend on particle size. These results imply that the reaction occurs essentially at the surface of the particle. A simple model for this type of reaction that reproduces the general trends observed is presented. the presence of formaldehyde did not affect the reaction rate.

Fried, Alan↗
NASA NTRS1995

Heterogeneous Reactions of HNO3(g) + NaCl(s) Yields HCL(g) + NaNO3(s) and N2O5(g) + NaCl(s) Yields ClNo2(g) + NaNO3(s)

The heterogeneous reactions of HNO3(g) + NaCl(s) Yields HCL(g) + NaNO3(s) and N2O5(g) + NaCl(s) Yields ClNo2(g) + NaNO3(s)were investigated over a temperature range of 223-296 K in a flow-tube reactor coupled to a quadrupole mass spectrometer. The implications for volcanic enhancement of the HCl and HNO3 column density in the lower stratosphere are discussed.

heterogeneous↗
DOE OSTI2020

Materials Data on CuH10C2(N2O5)2 by Materials Project

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on H20C3(N2O5)2 by Materials Project

(NH4)4H2(CO3)3H2O crystallizes in the triclinic P1 space group. The structure is zero-dimensional and consists of four ammonium molecules, one schembl1250901 molecule, and one water molecule.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Li2Pd(N2O5)2 by Materials Project

Li2N3O8PdNO2 crystallizes in the orthorhombic Pna2_1 space group. The structure is one-dimensional and consists of four nitrous acid molecules; four palladium on carbon molecules; and two Li2N3O8 ribbons oriented in the (1, 0, 0) direction. In each Li2N3O8 ribbon, there are two inequivalent Li1+ sites. In the first Li1+ site, Li1+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Li–O bond distances ranging from 1.95–2.36 Å. In the second Li1+ site, Li1+ is bonded in a distorted square pyramidal geometry to five O2- atoms. There are a spread of Li–O bond distances ranging from 1.97–2.25 Å. There are three inequivalent N4+ sites. In the first N4+ site, N4+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.24 Å) and one longer (1.25 Å) N–O bond length. In the second N4+ site, N4+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.23 Å) and one longer (1.25 Å) N–O bond length. In the third N4+ site, N4+ is bonded in a bent 120 degrees geometry to two O2- atoms. There is one shorter (1.23 Å) and one longer (1.25 Å) N–O bond length. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Li1+ atoms. In the second O2- site, O2- is bonded in a bent 150 degrees geometry to one Li1+ and one N4+ atom. In the third O2- site, O2- is bonded in a bent 120 degrees geometry to one Li1+ and one N4+ atom. In the fourth O2- site, O2- is bonded in a water-like geometry to two Li1+ atoms. In the fifth O2- site, O2- is bonded in a 1-coordinate geometry to two Li1+ and one N4+ atom. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to two Li1+ and one N4+ atom. In the seventh O2- site, O2- is bonded in a single-bond geometry to one N4+ atom. In the eighth O2- site, O2- is bonded in a single-bond geometry to one N4+ atom.

36 MATERIALS SCIENCE↗