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DOE OSTI2020

Materials Data on Li3P11(H3N)17 by Materials Project

(Li(NH3)4)3(P)11(NH3)5 crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of ten ammonia molecules, six Li(NH3)4 clusters, and two P clusters. In two of the Li(NH3)4 clusters, Li is bonded in a tetrahedral geometry to four N atoms. There are a spread of Li–N bond distances ranging from 2.04–2.10 Å. There are four inequivalent N sites. In the first N site, N is bonded to one Li and three H atoms to form distorted corner-sharing NLiH3 tetrahedra. All N–H bond lengths are 1.03 Å. In the second N site, N is bonded to one Li and three H atoms to form distorted corner-sharing NLiH3 tetrahedra. There is two shorter (1.02 Å) and one longer (1.03 Å) N–H bond length. In the third N site, N is bonded to one Li and three H atoms to form distorted corner-sharing NLiH3 tetrahedra. All N–H bond lengths are 1.03 Å. In the fourth N site, N is bonded to one Li and three H atoms to form distorted corner-sharing NLiH3 tetrahedra. All N–H bond lengths are 1.03 Å. There are twelve inequivalent H sites. In the first H site, H is bonded in a single-bond geometry to one N atom. In the second H site, H is bonded in a single-bond geometry to one N atom. In the third H site, H is bonded in a single-bond geometry to one N atom. In the fourth H site, H is bonded in a single-bond geometry to one N atom. In the fifth H site, H is bonded in a single-bond geometry to one N atom. In the sixth H site, H is bonded in a single-bond geometry to one N atom. In the seventh H site, H is bonded in a single-bond geometry to one N atom. In the eighth H site, H is bonded in a single-bond geometry to one N atom. In the ninth H site, H is bonded in a single-bond geometry to one N atom. In the tenth H site, H is bonded in a single-bond geometry to one N atom. In the eleventh H site, H is bonded in a single-bond geometry to one N atom. In the twelfth H site, H is bonded in a single-bond geometry to one N atom. In four of the Li(NH3)4 clusters, Li is bonded in a tetrahedral geometry to four N atoms. There are a spread of Li–N bond distances ranging from 2.05–2.07 Å. There are four inequivalent N sites. In the first N site, N is bonded to one Li and three H atoms to form distorted corner-sharing NLiH3 tetrahedra. There is one shorter (1.02 Å) and two longer (1.03 Å) N–H bond length. In the second N site, N is bonded to one Li and three H atoms to form distorted corner-sharing NLiH3 tetrahedra. There is two shorter (1.02 Å) and one longer (1.03 Å) N–H bond length. In the third N site, N is bonded to one Li and three H atoms to form distorted corner-sharing NLiH3 tetrahedra. There is two shorter (1.02 Å) and one longer (1.03 Å) N–H bond length. In the fourth N site, N is bonded to one Li and three H atoms to form distorted corner-sharing NLiH3 tetrahedra. There is one shorter (1.02 Å) and two longer (1.03 Å) N–H bond length. There are twelve inequivalent H sites. In the first H site, H is bonded in a single-bond geometry to one N atom. In the second H site, H is bonded in a single-bond geometry to one N atom. In the third H site, H is bonded in a single-bond geometry to one N atom. In the fourth H site, H is bonded in a single-bond geometry to one N atom. In the fifth H site, H is bonded in a single-bond geometry to one N atom. In the sixth H site, H is bonded in a single-bond geometry to one N atom. In the seventh H site, H is bonded in a single-bond geometry to one N atom. In the eighth H site, H is bonded in a single-bond geometry to one N atom. In the ninth H site, H is bonded in a single-bond geometry to one N atom. In the tenth H site, H is bonded in a single-bond geometry to one N atom. In the eleventh H site, H is bonded in a single-bond geometry to one N atom. In the twelfth H site, H is bonded in a single-bond geometry to one N atom. In each P cluster, there are eleven inequivalent P sites. In the first P site, P is bonded in a trigonal non-coplanar geometry to three P atoms. There are a spread of P–P bond distances ranging from 2.17–2.27 Å. In the second P site, P is bonded in a trigonal non-coplanar geometry to three P atoms. There are a spread of P–P bond distances ranging from 2.17–2.26 Å. In the third P site, P is bonded in a trigonal non-coplanar geometry to three P atoms. There are a spread of P–P bond distances ranging from 2.18–2.27 Å. In the fourth P site, P is bonded in a trigonal non-coplanar geometry to three P atoms. There are one shorter (2.17 Å) and one longer (2.28 Å) P–P bond lengths. In the fifth P site, P is bonded in a trigonal non-coplanar geometry to three P atoms. There are one shorter (2.18 Å) and one longer (2.26 Å) P–P bond lengths. In the sixth P site, P is bonded in a trigonal non-coplanar geometry to three P atoms. There are one shorter (2.18 Å) and one longer (2.27 Å) P–P bond lengths. In the seventh P site, P is bonded in a trigonal non-coplanar geometry to three P atoms. In the eighth P site, P is bonded in an L-shaped geometry to two P atoms. In the ninth P site, P is bonded in an L-shaped geometry to two P atoms. In the tenth P site, P is bonded in a trigonal non-coplanar geometry to three P atoms. In the eleventh P site, P is bonded in an L-shaped geometry to two P atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2021

Agricultural Impacts on Nitrogen Cycling: Climate and Air Pollution (Final Technical Report)

We have successfully added a parameterization of ammonia emissions from synthetic fertilizer and manure from agriculture to Earth System Models. We have evaluated how emissions change in the future and the processes driving these changes. We have examined the impact of agricultural ammonia emissions on present-day air quality and have evaluated the impact of resolving the emissions with high temporal resolution. We have also examined the impact of how Earth System Models treat the cycling of emissions in soils. Our code, the Flows of Agricultural Nitrogen – version 2 – model (FANv2) has been run in both the CLM framework and the ELM framework. To my knowledge the code has not yet been fully implemented into ELM. Volatilization of ammonia (NH3) from fertilizers and livestock wastes forms a significant pathway of nitrogen losses in agricultural ecosystems and constitutes the largest source of atmospheric emissions of NH3. We have provided a major update to the process model FAN (Flow of Agricultural Nitrogen), which evaluates NH3 emissions interactively within an Earth system model; in this work, the Community Earth System Model (CESM) is used. The updated version (FANv2) includes a more detailed treatment of both physical and agricultural processes, which allows the model to differentiate between the volatilization losses from animal housings, manure storage, grazed pastures, and the application of manure and different types of mineral fertilizers. The modeled ammonia emissions are first evaluated at a local scale against experimental data for various types of fertilizers and manure, and they are subsequently run globally to evaluate NH3 emissions for 2010–2015 based on gridded datasets of fertilizer use and livestock populations. Comparison of regional emissions shows that FANv2 agrees with previous inventories for North America and Europe and is within the range of previous inventories for China. However, due to higher NH3 emissions in Africa, India, and Latin America, the global emissions simulated by FANv2(48 Tg N) are 30 %–40 % higher than in the existing inventories.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2021

Mitigation of Gaseous Emissions from Stored Swine Manure with Biochar: Effect of Dose and Reapplication on a Pilot-Scale

Rural communities are affected by gaseous emissions from intensive livestock production. Practical mitigation technologies are needed to minimize emissions from stored manure and improve air quality inside barns. In our previous research, the one-time surficial application of biochar to swine manure significantly reduced emissions of NH3 and phenol. We observed that the mitigation effect decreased with time during the 30-day trials. In this research, we hypothesized that bi-weekly reapplication of biochar could improve the mitigation effect on a wider range of odorous compounds using a larger scale and longer trials. The objective was to evaluate the effectiveness of biochar dose and reapplication on mitigation of targeted gases (NH3, odorous, volatile organic compounds VOCs, odor, greenhouse gases (GHG)) from stored swine manure on a pilot-scale setup over 8-weeks. The bi-weekly reapplication of the lower biochar dose (2 kg/m2) showed much higher significant percentage reductions in emissions for NH3 (33% without and 53% with reapplication) and skatole (42% without and 80% with reapplication), respectively. In addition, the reapplication resulted in the emergence of a statistical significance to the mitigation effect for all other targeted VOCs. Specifically, for indole, the percentage reduction improved from 38% (p = 0.47, without reapplication) to 78% (p = 0.018, with reapplication). For phenol, the percentage reduction improved from 28% (p = 0.71, without reapplication) to 89% (p = 0.005, with reapplication). For p-cresol, the percentage reduction improved from 31% (p = 0.86, without reapplication) to 74% (p = 0.028, with reapplication). For 4-ethyl phenol, the percentage emissions reduction improved from 66% (p = 0.44, without reapplication) to 87% (p = 0.007, with reapplication). The one-time 2 kg/m2 and 4 kg/m2 treatments showed similar effectiveness in mitigating all targeted gases, and no statistical difference was found between the dosages. The one-time treatments showed significant percentage reductions of 33% and 42% and 25% and 48% for NH3 and skatole, respectively. The practical significance is that the higher (one-time) biochar dose may not necessarily result in improved performance over the 8-week manure storage, but the bi-weekly reapplication showed significant improvement in mitigating NH3 and odorous VOCs. The lower dosages and the frequency of reapplication on the larger-scale should be explored to optimize biochar treatment and bring it closer to on-farm trials.

Chen, Baitong (ORCID:0000000266071253)↗

DOE OSTI2021

Fine Aerosol Acidity and Water during Summer in the Eastern North Atlantic

Aerosol pH governs many important atmospheric processes that occur in the marine boundary layer, including regulating halogen and sulfur chemistries, and nutrient fertilization of surface ocean waters. In this study, we investigated the acidity of PM1 over the eastern North Atlantic during the Aerosol and Cloud Experiments in Eastern North Atlantic (ACE-ENA) aircraft campaign. The ISORROPIA-II thermodynamic model was used to predict PM1 pH and water. We first investigated the sensitivities of PM1 pH and water predictions to gas-phase NH3 and HNO3 concentrations. Our sensitivity analysis indicated that even though NH3 and HNO3 were present at very low concentrations in the eastern North Atlantic during the campaign, PM1 pH calculations can still be sensitive to NH3 concentrations. Specifically, NH3 was needed to constrain the pH of populations of PM1 that had low mass concentrations of NH4+ and non-volatile cations (NVCs). We next assumed that gas-phase NH3 and HNO3 concentrations during the campaign were 0.15 and 0.09 µg m−3, respectively, based on previous measurements conducted in the eastern North Atlantic. Using the assumption that PM1 were internally mixed (i.e., bulk PM1), we determined that PM1 pH ranged from 0.3–8.6, with a mean pH of 5.0 ± 2.3. The pH depended on both Hair+ and Wi. Hair+ was controlled primarily by the NVCs/SO42− molar ratio, while Wi was controlled by the SO42− mass concentration and RH. Changes in pH with altitude were driven primarily by changes in SO42−. Since aerosols in marine atmospheres are rarely internally mixed, the scenario where non-sea salt species and sea-salt species were present in two separate aerosol modes in the PM1 (i.e., completely externally mixed) was also considered. Smaller pH values were predicted for the aerosol mode comprised only of non-sea salt species compared to the bulk PM1 (difference of around 1 unit on average). This was due to the exclusion of sea-salt species (especially hygroscopic alkaline NVCs) in this aerosol mode, which led to increases in Hair+ values and decreases in Wi values. This result demonstrated that assumptions of aerosol mixing states can impact aerosol pH predictions substantially, which will have important implications for evaluating the nature and magnitude of pH-dependent atmospheric processes that occur in the marine boundary layer.

54 ENVIRONMENTAL SCIENCES↗

NASA NTRS1983

Prebiotic synthesis in atmospheres containing CH4, CO, and CO2. I - Amino acids

The prebiotic synthesis of amino acids, HCN, H2CO, and NH3 using a spark discharge on various simulated primitive earth atmospheres at 25 C is investigated. Various mixtures of CH4, CO, CO2, N2, NH3, H2O, and H2 were utilized in different experiments. The yields of amino acids (1.2-4.7 percent based on the carbon) are found to be approximately independent of the H2/CH4 ratio and the presence of NH3, and a wide variety of amino acids are obtained. Glycine is found to be almost the only amino acid produced from CO and CO2 model atmospheres, with the maximum yield being about the same for the three carbon sources at high H2/carbon ratios,whereas CH4 is superior at low H2/carbon ratios. In addition, it is found that the directly synthesized NH3 together with the NH3 obtained from the hydrolysis of HCN, nitriles, and urea could have been a major source of ammonia in the atmosphere and oceans of the primitive earth. It is determined that prebiotic syntheses from HCN and H2CO to give products such as purines and sugars and some amino acids could have occurred in primitive atmospheres containing CO and CO2 provided the H2/CO and H2/CO2 ratios were greater than about 1.0.

Schlesinger, G.↗

NASA NTRS1985

Aircraft measurements of ammonia and nitric acid in the lower troposphere

The first simultaneous measurements of ammonia and nitric acid in the troposphere have been made from an aircraft using a tungsten oxide denuder system. Vertical profiles of NH3 and HNO3 taken over coastal Virginia and Maryland in March and September, 1983, at altitudes from 150 m to 3000 m, show mixing ratios that decrease with altitude. Ammonia profiles show substantial seasonal variation, while nitric acid profiles do not. Using the measured profiles and a one-dimensional photochemical model, lifetimes due to heterogeneous loss of one day for HNO3 and ten days for NH3 are calculated. In contrast, NH3 profiles up to 5300 m over the North Atlantic Ocean during August 1982 show mixing ratios that increase slightly with altitude. These data represent the first ammonia profiles measured over the ocean. It is suggested that the increase in NH3 with altitude is a result of an ammonia-rich continental air mass advected over the ocean, followed by the dissolution of NH3 in the marine boundary layer on water-covered sea salt particles.

Lebel, P. J.↗

NASA NTRS1987

The role of aqueous chemistry in determining the composition and cloud structure of the upper troposphere on Uranus

Aqueous chemistry on Uranus affects the atmospheric abundances of NH3 and H2S below the methane cloud base. Here a complete thermochemical equilibrium model for the H2O-NH3-H2S system is presented. Inclusion of H2S increases the aqueous removal of NH3 to 20-30 percent, but aqueous chemistry alone cannot account for the depletion of NH3 in the 150-200-K region of the atmosphere required to fit microwave observations. Formation of NH4SH clouds can account for the observed depletion provided the H2S/NH3 ratio is enhanced by a factor of 4 relative to solar. Perturbations to the chemical balance between N and S, for example by the general circulation on Uranus, would then produce regions with either NH3 or H2S aloft.

Carlson, Barbara E.↗

NASA NTRS1992

Chemistry of the outer planets

Various aspects were studied of past or present chemistry in the atmospheres of the outer planets and their satellites using lab simulations. Three areas were studied: (1) organic chemistry induced by kinetically hot hydrogen atoms in the region of Jupiter's atmosphere containing the ammonia cirrus clouds; (2) the conversion of NH3 into N2 by plasmas associated with entry of meteors and other objects into the atmosphere of early Titan; and (3) the synthesis of simple hydrocarbons and HCN by lightning in mixtures containing N2, CH4, and NH3 representing the atmospheres of Titan and the outer planets. The results showed that: (1) hot H2 atoms formed from the photodissociation of NH3 in Jupiter's atmosphere could account for some of the atmospheric chemistry in the ammonia cirrus cloud region; (2) the thermalization of hot H2 atoms in atmospheres predominated by molecular H is not as rapid as predicted by elastic collision theory; (3) the net quantum loss of NH3 in the presence of a 200 fold excess of H2 is 0.02, much higher than was expected from the amount of H2 present; (4) the conversion of NH3 into N2 in plasmas associated with infalling meteors is very efficient and rapid, and could account for most of the N2 present on Titan; (5) the yields of C2H2 and HCN from lightning induced chemistry in mixtures of CH4 and N2 is consistent with quenched thermodynamic models of the discharge core; and (6) photolysis induced by the UV light emitted by the gases in the hot plasmas may account for some, if not most, of the excess production of C2H6 and the more complex hydrocarbons.

Scattergood, Thomas W.↗

NASA NTRS1992

Ortho-para-hydrogen equilibration on Jupiter

Voyager IRIS observations reveal that the Jovian para-hydrogen fraction is not in thermodynamic equilibrium near the NH3 cloud top, implying that a vertical gradient exists between the high-temperature equilibrium value of 0.25 at depth and the cloud top values. The height-dependent para-hydrogen profile is obtained using an anisotropic multiple-scattering radiative transfer model. A vertical correlation is found to exist between the location of the para-hydrogen gradient and the NH3 cloud, strongly suggesting that paramagnetic conversion on NH3 cloud particle surfaces is the dominant equilibration mechanism. Below the NH3 cloud layer, the para fraction is constant with depth and equal to the high-temperature equilibrium value of 0.25. The degree of cloud-top equilibration appears to depend on the optical depth of the NH3 cloud layer. Belt-zone variations in the para-hydrogen profile seem to be due to differences in the strength of the vertical mixing.

Carlson, Barbara E.↗

NASA NTRS1993

Flow of ices in the Ammonia-Water System

We have fabricated in the laboratory and subsequently deformed crystalline hydrates and partial melts of the water-rich end of the NH3-H2O system, with the aim of improving our understanding of physical processes occurring in icy moons of the outer solar system. Deformation experiments were carried out at constant strain rate. The range of experimental variables are given. Phase relationships in the NH3-H2O system indicate that water ice and ammonia dihydrate, NH3-2H2O, are the stable phases under our experiment conditions. X-ray diffraction of our samples usually revealed these as the dominant phases, but we have also observed an amorphous phase (in unpressurized samples only) and occasionally significant ammonia monohydrate, NH3-H2O. The onset of partial melting at the peritectic temperature at about 176 K appeared as a sharp transition in strength observed in samples of x(sub NH3) = 0.05 and 0.01, the effect of melt was less pronounced. For any given water ice + dihydrate alloy in the subsolidus region, we observed one rheological law over the entire temperature range from 175 K to about 140 K. Below 140 K, a shear instability similar to that occurring in pure water ice under the same conditions limited our ability to measure ductile flow. The rheological laws for the several alloys vary systematically from that of pure ice to that of dihydrate. Pure dihydrate is about 4 orders of magnitude less viscous than water ice just below the peritectic temperature, but because of a very pronounced temperature dependence in dihydrate (100 kJ/mol versus 43 kJ/mol for water ice) the viscosity of dihydrate equals or exceeds that of water ice at T less than 140 K. The large variation in viscosity of dihydrate with relatively small changes in temperature may be helpful in explaining the rich variety of tectonic and volcanic features seen on the surfaces of icy moons in the outer solar system.

Durham, W. B.↗

NASA NTRS1998

Unraveling the 10 micron "silicate" feature of protostars: the detection of frozen interstellar ammonia

We present infrared spectra of four embedded protostars in the 750-1230 cm-1 (13.3-8.1 microns) range. For NGC 7538 IRS 9, a new band is reported at 1110 cm-1 (9.01 microns, and several others may be present near 785, 820, 900, 1030, and 1075 cm-1 (12.7, 12.2, 11.1, 9.71, and 9.30 microns). The band 1110 cm-1 is attributed to frozen NH3. Its position and width imply that the NH3 is frozen in a polar, H2O-rich interstellar ice component. The NH3/H2O ice ratio inferred for NGC 7538 IRS 9 is 0.1, making NH3 as important a component as CH3OH and CO2 in the polar ices along this line of sight. At these concentrations, hydrogen bonding between the NH3 and H2O can account for much of the enigmatic low-frequency wing on the 3240 cm-1 (3.09 microns) H2O interstellar ice band. The strength of the implied NH3 deformation fundamental at 1624 cm-1 (6.158 microns) can also account for the absorption at this position reported by ISO.

NASA Center ARC↗

NASA NTRS2000

Biological removal of gaseous ammonia in biofilters: space travel and earth-based applications

Gaseous NH3 removal was studied in laboratory-scale biofilters (14-L reactor volume) containing perlite inoculated with a nitrifying enrichment culture. These biofilters received 6 L/min of airflow with inlet NH3 concentrations of 20 or 50 ppm, and removed more than 99.99% of the NH3 for the period of operation (101, 102 days). Comparison between an active reactor and an autoclaved control indicated that NH3 removal resulted from nitrification directly, as well as from enhanced absorption resulting from acidity produced by nitrification. Spatial distribution studies (20 ppm only) after 8 days of operation showed that nearly 95% of the NH3 could be accounted for in the lower 25% of the biofilter matrix, proximate to the port of entry. Periodic analysis of the biofilter material (20 and 50 ppm) showed accumulation of the nitrification product NO3- early in the operation, but later both NO2- and NO3- accumulated. Additionally, the N-mass balance accountability dropped from near 100% early in the experiments to approximately 95 and 75% for the 20- and 50-ppm biofilters, respectively. A partial contributing factor to this drop in mass balance accountability was the production of NO and N2O, which were detected in the biofilter exhaust.

NASA Discipline Life Support Systems↗

NASA NTRS2015

The Compositional Evolution of C/2012 S1 (ISON) from Ground-Based High-Resolution Infrared Spectroscopy as Part of a Worldwide Observing Campaign

Volatile production rates, relative abundances, rotational temperatures, and spatial distributions in the coma were measured in C/2012 S1 (ISON) using long-slit high-dispersion (lambda/delta lambda approximately 2.5 times 10 (sup 4)) infrared spectroscopy as part of a worldwide observing campaign. Spectra were obtained on Universal Time 2013 October 26 and 28 with NIRSPEC (Near Infrared Spectrometer) at the W.M. Keck Observatory, and Universal Time 2013 November 19 and 20 with CSHELL (Cryogenic Echelle Spectrograph) at the NASA IRTF (Infrared Telescope Facility). H2O was detected on all dates, with production rates increasing markedly from (8.7 plus or minus 1.5) times 10 (sup 27) molecules per second on October 26 (Heliocentric Distance = 1.12 Astronomical Units) to (3.7 plus or minus 0.4) times 10 (sup 29) molecules per second on November 20 (Heliocentric Distance = 0.43 Astronomical Units). Short-term variability of H2O production is also seen as observations on November 19 show an increase in H2O production rate of nearly a factor of two over a period of about 6 hours. C2H6, CH3OH and CH4 abundances in ISON (International Scientific Optical Network) are slightly depleted relative to H2O when compared to mean values for comets measured at infrared wavelengths. On the November dates, C2H2, HCN and OCS abundances relative to H2O appear to be within the range of mean values, whereas H2CO and NH3 were significantly enhanced. There is evidence that the abundances with respect to H2O increased for some species but not others between October 28 (Heliocentric Distance = 1.07 Astronomical Units) and November 19 (Heliocentric Distance = 0.46 Astronomical Units). The high mixing ratios of H2CO to CH3OH and C2H2 to C2H6 on November 19, and changes in the mixing ratios of some species with respect to H2O between October 28 to November 19, indicates compositional changes that may be the result of a transition from sampling radiation-processed outer layers in this dynamically new comet to sampling more pristine natal material as the outer processed layer was increasingly eroded and the thermal wave propagated into the nucleus as the comet approached perihelion for the first time. On November 19 and 20, the spatial distribution for dust appears asymmetric and enhanced in the antisolar direction, whereas spatial distributions for volatiles (excepting CN) appear symmetric with their peaks slightly offset in the sunward direction compared to the dust. Spatial distributions for H2O, HCN, C2H6, C2H2, and H2CO on November 19 show no definitive evidence for significant contributions from extended sources; however, broader spatial distributions for NH3 and OCS may be consistent with extended sources for these species. Abundances of HCN and C2H2 on November 19 and 20 are insufficient to account for reported abundances of CN and C2 in ISON near this time. Differences in HCN and CN spatial distributions are also consistent with HCN as only a minor source of CN in ISON on November 19 as the spatial distribution of CN in the coma suggests a dominant distributed source that is correlated with dust and not volatile release. The spatial distributions for NH3 and NH2 are similar, suggesting that NH3 is the primary source of NH2 with no evidence of a significant dust source of NH2; however, the higher production rates derived for NH3 compared to NH2 on November 19 and 20 remain unexplained. This suggests a more complete analysis that treats NH2 as a distributed source and accounts for its emission mechanism is needed for future work.

Russo, N. Dello↗

NASA NTRS2016

En Route to Destruction: the Evolution in Composition of Ices in Comet D 2012 S1 (ISON) Between 1.2 and 0.34 Au from the Sun as Revealed at Infrared Wavelengths

We report production rates for H2O and eight trace molecules (CO, C2H6, CH4, CH3OH, NH3, H2CO, HCN, C2H2) in the dynamically new, Sun-grazing Comet C2012 S1 (ISON), using high-resolution spectroscopy at Keck II and the NASA IRTF on 10pre-perihelion dates encompassing heliocentric distances Rh1.210.34 AU. Measured water production rates spanned two orders of magnitude, consistent with a long-term heliocentric power law Q(H2O) Rh-3.10.1). Abundance ratios for CO, C2H6, and CH4 with respect to H2O remained constant with Rh and below their corresponding mean values measured among a dominant sample of Oort Cloud comets. CH3OH was also depleted for Rh 0.5 AU, but was closer to its mean value for Rh0.5 AU. The remaining four molecules exhibited higher abundance ratios within 0.5 AU: for Rh 0.8 AU, NH3 and C2H2 were consistent with their mean values while H2CO and HCN were depleted. For Rh 0.5 AU, all four were enriched, with NH3, H2CO, and HCN increasing most. Spatial profiles of gas emission in ISON consistently peaked sunward of the dust continuum, which was asymmetric antisunward and remained singly peaked for all observations. NH3 within 0.5 AU showed a broad spatial distribution, possibly indicating its release in the coma provided that optical depth effects were unimportant. The column abundance ratio NH2H2O at 0.83 AU was close to the typical NHOH from optical wavelengths, but was higher within 0.5 AU. Establishing its production rate and testing its parentage (e.g., NH3) require modeling of coma outflow.

Disanti, M. A.↗

DOE OSTI2021

All-aerosol-jet-printed highly sensitive and selective polyaniline-based ammonia sensors: a route toward low-cost, low-power gas detection

In this work, we report the design and scalable fabrication of a low-cost and low-power polyaniline-based (PANI) ammonia (NH3) gas sensor on polyimide (PI) substrates using additive manufacturing techniques. The silver interdigitated electrode (IDE) arrays and conducting polymer films are printed onto PI using a direct-write technology of aerosol-jet printing. Morphological characteristics are examined by scanning electron microscopy and energy-dispersive X-ray analysis which reveal homogeneously printed PANI film on the IDE platform. The gas sensing performance is evaluated in the analytical early leak detection range of 5–1000 ppm NH3 in air as a function of both thermal (23 °C, 50 °C, 80 °C) and relative humidity (RH = 0%, 30%, 50%) exposures. The sensor exhibits sensitivity down to 5 ppm NH3 with a sub-ppm detection limit and good repeatability. We observe rapid NH3 detection at 0% RH with very extended times for equilibration and recovery. However, at both 30 and 50% RH, the room temperature response and recovery times are reduced to only about 1 min and 5 min, respectively. Experiments also reveal good sensitivity toward the analyte even at higher operating temperatures. Present results merit the practical application of aerosol-jet-printed, low-power sensors for industrial applications where low-level hazardous gas detection is essential.

36 MATERIALS SCIENCE↗

DOE OSTI2021

Laser-induced electron diffraction of the ultrafast umbrella motion in ammonia

Visualizing molecular transformations in real-time requires a structural retrieval method with Ångström spatial and femtosecond temporal atomic resolution. Imaging of hydrogen-containing molecules additionally requires an imaging method sensitive to the atomic positions of hydrogen nuclei, with most methods possessing relatively low sensitivity to hydrogen scattering. Laser-induced electron diffraction (LIED) is a table-top technique that can image ultrafast structural changes of gas-phase polyatomic molecules with sub-Ångström and femtosecond spatiotemporal resolution together with relatively high sensitivity to hydrogen scattering. Here, we image the umbrella motion of an isolated ammonia molecule (NH3) following its strong-field ionization. Upon ionization of a neutral ammonia molecule, the ammonia cation (NH3+) undergoes an ultrafast geometrical transformation from a pyramidal (ΦHNH=107°) to planar (ΦHNH=120°) structure in approximately 8 femtoseconds. Using LIED, we retrieve a near-planar (ΦHNH=117 ± 5°) field-dressed NH3+ molecular structure 7.8−9.8 femtoseconds after ionization. Our measured field-dressed NH3+ structure is in excellent agreement with our calculated equilibrium field-dressed structure using quantum chemical ab initio calculations.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2022

A survey of deuterated ammonia in the Cepheus star-forming region L1251

ABSTRACT Understanding the chemical processes during starless core and prestellar core evolution is an important step in understanding the initial stages of star and disc formation. This project is a study of deuterated ammonia, o-NH2D, in the L1251 star-forming region towards Cepheus. Twenty-two dense cores (20 of which are starless or prestellar, and two of which have a protostar), previously identified by p-NH3 (1,1) observations, were targeted with the 12m Arizona Radio Observatory telescope on Kitt Peak. o-NH2D J$_{\rm {K_a} \rm {K_c}}^{\pm } =$$1_{11}^{+} \rightarrow 1_{01}^{-}$ was detected in 13 (59 per cent) of the NH3-detected cores with a median sensitivity of $\sigma _{T_{mb}} = 17$ mK. All cores detected in o-NH2D at this sensitivity have p-NH3 column densities >1014 cm−2. The o-NH2D column densities were calculated using the constant excitation temperature (CTEX) approximation while correcting for the filling fraction of the NH3 source size. The median deuterium fraction was found to be 0.11 (including 3σ upper limits). However, there are no strong, discernible trends in plots of deuterium fraction with any physical or evolutionary variables. If the cores in L1251 have similar initial chemical conditions, then this result is evidence of the cores physically evolving at different rates.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2020

Materials Data on Ag2H21N7(ClO4)2 by Materials Project

(Ag(NH3)2)2(AgN3H7O4)2(NH3)2(H2)2(NH2O)2H2O2(ClO2)2Cl2 crystallizes in the triclinic P1 space group. The structure is zero-dimensional and consists of one ammonia molecule, one hydrochloric acid molecule, one hydrogen molecule, one hydroxylamine molecule, one hypochlorous acid;hydrate molecule, one water molecule, one Ag(NH3)2 cluster, and one AgN3H7O4 cluster. In the Ag(NH3)2 cluster, Ag1+ is bonded in a distorted bent 120 degrees geometry to two N+0.71- atoms. There are one shorter (2.14 Å) and one longer (2.15 Å) Ag–N bond lengths. There are two inequivalent N+0.71- sites. In the first N+0.71- site, N+0.71- is bonded in a distorted trigonal non-coplanar geometry to one Ag1+ and three H1+ atoms. All N–H bond lengths are 1.02 Å. In the second N+0.71- site, N+0.71- is bonded in a distorted trigonal non-coplanar geometry to one Ag1+ and three H1+ atoms. There is two shorter (1.02 Å) and one longer (1.06 Å) N–H bond length. There are six inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one N+0.71- atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one N+0.71- atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one N+0.71- atom. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one N+0.71- atom. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one N+0.71- atom. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one N+0.71- atom. In the AgN3H7O4 cluster, Ag1+ is bonded in a 2-coordinate geometry to three N+0.71- atoms. There are a spread of Ag–N bond distances ranging from 2.05–2.71 Å. There are three inequivalent N+0.71- sites. In the first N+0.71- site, N+0.71- is bonded in a 2-coordinate geometry to one Ag1+, two H1+, and one O2- atom. Both N–H bond lengths are 1.03 Å. The N–O bond length is 1.46 Å. In the second N+0.71- site, N+0.71- is bonded in a distorted bent 120 degrees geometry to one Ag1+ and one H1+ atom. The N–H bond length is 1.04 Å. In the third N+0.71- site, N+0.71- is bonded in a distorted trigonal non-coplanar geometry to one Ag1+ and three H1+ atoms. All N–H bond lengths are 1.03 Å. There are seven inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one N+0.71- atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one N+0.71- atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one N+0.71- atom. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one N+0.71- atom. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one N+0.71- atom. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one N+0.71- atom. In the seventh H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.06 Å) and one longer (1.48 Å) H–O bond length. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one N+0.71- and one O2- atom. The O–O bond length is 1.34 Å. In the second O2- site, O2- is bonded in a distorted single-bond geometry to one H1+ and one O2- atom. In the third O2- site, O2- is bonded in a single-bond geometry to one H1+ and one O2- atom. The O–O bond length is 1.34 Å. In the fourth O2- site, O2- is bonded in a distorted single-bond geometry to one O2- atom.

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