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The results of CASSCF/CCI calculations with large atomic-natural-orbital basis sets are presented for the H + NO region of the lowest three potential surfaces of HNO. The calculations focus on the minimum-energy path for H atom addition to the N end of NO and on the equilibrium geometry region of HNO and HON.
An accurate ab initio quartic force field for HNO has been determined using the singles and doubles coupled-cluster method that includes a perturbational estimate of the effects of connected triple excitations, CCSD(T), in conjunction with the correlation consistent polarized valence triple zeta (cc-pVTZ) basis set. Improved harmonic frequencies were determined with the cc-pVQZ basis set. Fundamental vibrational frequencies were determined using a second-order perturbation theory analysis and also using variational calculations. The N-0 stretch and bending fundamentals are determined well from both vibrational analyses. The H-N stretch, however, is shown to have an unusually large anharmonic correction, and is not well determined using second-order perturbation theory. The H-N fundamental is well determined from the variational calculations, demonstrating the quality of the ab initio quartic force field. The zero-point energy of HNO that should be used in isodesmic reactions is also discussed.
Here, the uptake behavior of 73 As and 75 Se was studied in HCl and HNO3 media with CL resin, ethanethiol resin and dimethyl sulfide resin. In HCl solutions, there was high extraction of selenium on CL resin and ethanethiol resin but lower uptake on dimethyl sulfide resin; arsenic was only extracted by CL resin. From HNO 3 , selenium was extracted only by ethanethiol resin and CL resin and there was no uptake of arsenic on any resin. While the sulfur-based resins have high selenium uptake and selectivity, column separations are challenging due to the chemical instability of these resins.
We report the water-mediated charge separation of nitric acid upon incorporation into size-selected Cs + ∙(HNO 3 )(H 2 O) n=0-11 clusters at 20 K. Dramatic spectral changes are observed in the range n=7-9 that are traced to the formation of many isomeric structures associated with intermediate transfer of the acidic proton to the water network. This transfer is complete by n=10, which exhibits much simpler vibrational band patterns consistent with those expected for a tri-coordinated hydronium ion (the Eigen motif) along with the NO stretching bands predicted for a hydrated NO 3 – anion that is directly complexed to the Cs + cation. Theoretical analysis of the n=10 spectrum indicates that the dissociated ions adopt a solvent-separated ion-pair configuration such that the Cs + and H 3 O + cations flank the NO 3 – anion in a microhydrated salt bridge. In conclusion, this charge separation motif is evidently assisted by the electrostatic stabilization of the product NO 3 – /H 3 O + ion pair by the proximal metal ion.
The structural geometries, formation enthalpies, and dissociation energies of all diatomic and triatomic molecules consisting of the four basic elements C, H, N, and/or O are calculated using the projector augmented wave density functional theory (DFT) method with the Perdew–Burke–Ernzerhof and optB88-vdW exchange-correlation functionals. The calculations are also extended to two larger molecules NO 3 and HNO 3 , which consist of four and five atoms, respectively. In total, 82 molecules or isomers are considered in the calculations. The geometric parameters including 42 bond lengths and 15 bond angles of these molecules calculated using the planewave DFT method are highly satisfactory, relative to the available experimental data. The error analysis is also performed for 49 formation enthalpies and 138 dissociation energies (including 51 atomization energies as well as the corresponding bond dissociation energies). The results are also compared with the previous data from various atomic-orbital-based methods for molecules and from similar or different planewave DFT methods for various solids and other molecules. This provides an informative and instructive evaluation especially for calculating the large-size material systems containing these small molecules as well as for developing the DFT methods further.
We present Microwave Limb Sounder (MLS) measurements fo gas-phase HNO(sub 3) obtained at the beginning of five southern hemisphere winters.
Microwave Limb Sounder (MLS) measurements of lower stratospheric ClO and gas-phase HNO(sub 3) are presented for the 1996-97 Arctic winter.
Simultaneous in situ measurements of stratospheric NO(sub 2), HNO(sub 3), HCI, and CH(sub 4) 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.
NHO crystallizes in the monoclinic C2/c space group. The structure is zero-dimensional and consists of four 1,1-dihydroxyhydrazine molecules. there are two inequivalent N1+ sites. In the first N1+ site, N1+ is bonded in a 3-coordinate geometry to one N1+ and two equivalent O2- atoms. The N–N bond length is 1.17 Å. Both N–O bond lengths are 1.45 Å. In the second N1+ site, N1+ is bonded in a single-bond geometry to one N1+ atom. H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. O2- is bonded in a distorted water-like geometry to one N1+ and one H1+ atom.
NHO crystallizes in the monoclinic Cc space group. The structure is one-dimensional and consists of two NHO ribbons oriented in the (1, 0, 1) direction. there are two inequivalent N1+ sites. In the first N1+ site, N1+ is bonded in a 2-coordinate geometry to one N1+ and two O2- atoms. The N–N bond length is 1.19 Å. There is one shorter (1.40 Å) and one longer (1.42 Å) N–O bond length. In the second N1+ site, N1+ is bonded in a distorted bent 120 degrees geometry to one N1+ and one H1+ atom. The N–H bond length is 1.79 Å. 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 0.99 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one N1+ and one O2- atom. The H–O bond length is 1.01 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted water-like geometry to one N1+ and one H1+ atom. In the second O2- site, O2- is bonded in a distorted water-like geometry to one N1+ and one H1+ atom.
NHO crystallizes in the monoclinic C2/c space group. The structure is one-dimensional and consists of two NHO ribbons oriented in the (1, 0, 1) direction. there are two inequivalent N1+ sites. In the first N1+ site, N1+ is bonded in a distorted water-like geometry to one N1+ and two equivalent O2- atoms. The N–N bond length is 1.20 Å. Both N–O bond lengths are 1.38 Å. In the second N1+ site, N1+ is bonded in a distorted trigonal planar geometry to one N1+ and two equivalent H1+ atoms. Both N–H bond lengths are 1.61 Å. H1+ is bonded in a distorted linear geometry to one N1+ and one O2- atom. The H–O bond length is 1.05 Å. O2- is bonded in a distorted water-like geometry to one N1+ and one H1+ atom.
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The uptake of 241 Am, 244 Cm and 249 Cf with LN resin was studied in HCl and HNO3 solutions with concentrations ranging from 0.02 to 2.5 M. There is high uptake at concentrations < 0.1 M in both acids for all three isotopes with decreasing uptake at higher concentrations and negligible extraction at ≥ 0.6 M. Californium has a higher extraction than americium and curium, which are extremely similar. Kinetics studies showed rapid uptake of all three isotopes. Here, column studies were performed to demonstrate the separation of 241 Am and 249 Cf, and a bulk separation including nine stable lanthanides along with 241 Am, 249 Cf, and 88 Y.
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Using a fast-flow reactor coupled to a quadrupole mass spectrometer, the heterogeneous reactions of C1ONO2 + HCl and HOCl + HCl as well as hydrolysis of N2O5 and C1ONO2 were investigated on liquid sulfuric acid, with particular emphasis on the effect of incorporation of HNO3 on the reaction probabilities.