Electron Affinity Of NO Research Articles

Electronic and geometric structure analysis of neutral and anionic metal nitric chalcogens: The case of MNX series (M=Li, Na, Be and X=O, S, Se, Te).

Coupled cluster and multireference configuration approaches are employed to study the electronic and geometric structures of mono-coordinated complexes of lithium, sodium, and beryllium with nitric oxide and its isovalent NS, NSe, and NTe species. Ground and low-lying excited states were examined for both linear-bonded and side-bonded isomers. We show that the ionic M+ NX- (M=Li, Na, Be and X=O, S, Se, Te) picture is a more natural representation and can account for the symmetry of the low-lying electronic states as Σ- , Δ, and Σ+ , the smaller excitation energies and the larger binding energies for heavier X. An additional electron binds to the positively charged Li and Na terminal creating stable anions. The electron affinity (EA) of LiNX and NaNX species is in the 0.5-0.8 eV range. Despite the negative EA of beryllium and the very small EA of NO, the BeNO molecule has an EA of ~1.0 eV, which is increased to ~1.5 eV for the heavier BeNX species. This is attributed to the fact that the additional electron goes to the beryllium end for BeNO but to a π(MN)π*(NX) orbital of the rest species. Our accurate results contradict previous findings and serve as a guide for future experimental studies. © 2019 Wiley Periodicals, Inc.

Electronic structure, stability and spectroscopy of low-lying states of NO−, HNO− and HON− molecular anions

Accurate post Hartree-Fock methods have been used to investigate electronic structure, spectroscopy, stability and metastability of low-lying electronic states of HNO, HON, NO, NO−, HNO− and HON−. Accurate vertical transition energies between lowest electronic states of HNO and HON isomers have been determined. The HNO vertical transition energy of the X∼1A′-ã3A″ transition is shown to be 0.87eV. Core-valence correlations and relativistic corrections have been taken into account to determine accurately spectroscopic constants of electronic states of NO− and NO. Adiabatic excitation energies and dipole moments of low-lying electronic states of NO− have also been calculated. The adiabatic electron affinity of NO has been deduced to be 0.0289eV, which is in excellent agreement with the experimental value of 0.026±0.05eV. The comparison of potential energy curves of low-lying states of NO/NO−, HNO/HNO− and HON/HON− reveals short-lived excited electronic states. The HON− anion appears as an unbound anion unlike to HNO− which is a bound anion. Three-dimensional potential energy surfaces (3D-PESs) for both HNO (X∼1A′) and HNO−(X2A″) ground states, have been generated and fitted by second order perturbation theory to produce accurate spectroscopic constants. Spectroscopic data of HNO−(X2A″) deduced from this work is computed for the first time.

MRCISD and GVVPT3 study of the low-lying electronic states of NO−

The ground electronic state (X 3Σ−) and three low-lying excited electronic states, 11Σ+, 11Δ, and 13Π, of NO− were studied using MRCISD and GVVPT3 with the aug-cc-pVXZ (X = D, T, Q) basis sets and extrapolated to complete basis set limits. The thermodynamic constants, re , ωe , ωexe , and De , are predicted to be in good agreement with experimental values, where available. The increase of basis set lowers substantially the potential well of 13Π with respect to the ground state, e.g. the value of Te , 18425 cm−1 by MRCISD/aug-cc-pVDZ, decreases to 10829 cm−1 by MRCISD at the complete basis set limit. Additional calculations, using perturbative corrections for triple and quadruple excitations to MRCISD, i.e. MRCISD(TQ), showed that inclusion of triples and quadruples are essential to predictions of the electron affinity of NO, resulting in an increase in electron binding of over 0.36 eV.

Electron Affinity of NO

The electron affinity of NO has been measured to be 0.026 eV by laser photodetachment experiments. This low electron affinity (just 2.5 kJ/mol or 210 cm-1) presents a computational challenge that requires careful attention to several aspects of the computational procedure required to predict the electron affinity of NO from first principles. We have used augmented correlation consistent basis sets with several coupled cluster methods to calculate the molecular energies, bond dissociation energies, bond lengths, vibrational frequencies, and potential energy curves for NO and NO-. The electron affinity of NO, EA0, using the CCSD(T) method and extrapolating to the complete basis set limit, is calculated to be 0.028 eV. The calculated bond dissociation energies, D0, for NO and NO- are 622 and 487 kJ/mol, respectively, compared with experimental values of 626.8 and 487.8 kJ/mol. From the calculated potential energy curves for NO and NO- the vibrational wavefunctions were determined. The calculated vibrational wavefunctions predict Franck-Condon factor ratios in good agreement with the values determined in the photodetachment experiment.

Computational study on the negative electron affinities of NO2−∙(H2O)n clusters (n=–30)

Here we report negative electron affinities of NO(2)(-).(H2O)n clusters (n=0-30) obtained from density functional theory calculations and a simple correction to Koopmans' theorem. The method relies on the calculation of the detachment energy of the monoanion and its highest occupied molecular orbital and lowest unoccupied molecular orbital energies, and explicit calculations on the dianion itself are avoided. A good agreement with resonances in the cross section for neutral production in electron scattering experiments is found for n=0, 1, and 2. We find several isomeric structures of NO(2)(-).(H2O)2 of similar energy that elucidate the interplay between water-water and ion-water interactions. The topology is predicted to influence the electron affinity by 0.5 and 0.4 eV for NO(2)(-).(H2O) and NO(2)(-).(H2O)2, respectively. The electron affinity of larger clusters is shown to follow a (n+delta)-1/3 dependence, where delta=3 represents the number of water molecules that in volume, could replace NO(2) (-).

The gas and solution phase acidities of HNO, HOONO, HONO, and HONO 2

The acidities of HNO x (where x=1–3) have been calculated in the gas phase and in solution by using high level ab initio molecular orbital theory. Coupled cluster (CCSD(T)) energies, extrapolated to the complete basis set (CBS) limit, were used to determine thermodynamic properties of the species in the gas phase, and the fully polarizable continuum model (FPCM) was used to calculate the effect of solvent on the energy changes. The calculated gas phase heats of formation in kcal mol −1 at 0 K, based on extrapolations through the aug-cc-pVQZ basis set, are: Δ H f(NO)=22.07 (calculated) vs. 21.46±0.04 (experimental); Δ H f(HNO)=26.39 (calculated) vs. 26.3±1 (experimental); Δ H f(NO 2)=10.12 (calculated) vs. 8.59±0.2 (experimental); Δ H f(HONO 2)=−29.87 (calculated) vs. −29.75±0.1 (experimental); Δ H f(HONO)=−15.79 (calculated) vs. −17.37±0.32 (experimental); Δ H f(HOONO)=−0.89 (calculated); Δ H f(NO 2 −)=−41.95 (calculated) vs. −43.8±0.2 (experimental); Δ H f(NO 3 −)=−70.76 (calculated) vs. −71.7±0.30 (experimental); and Δ H f(ONOO −)=−16.74 (calculated). The electron affinity of NO is calculated to be 0.62 kcal mol −1, based on extrapolations up through the aug-cc-pV5Z basis set, and falls within 0.02 kcal mol −1 of the experimental value. The corresponding heats of formation at 0 K in kcal mol −1 of the anions are: Δ H f(HNO)=26.93 (calculated); Δ H f(NO)=22.28 (calculated); Δ H f(NO −)=21.66 (calculated) vs. 20.86±0.16 (experimental). The calculated gas phase acidities of HNO, HONO, HOONO, and HONO 2 are found to be in excellent agreement with experiment to within 1 kcal mol −1. Solvation calculations show that the free energy change for K a in aqueous solution for HONO 2, HONO, and HNO can be calculated within ∼2, 3, and 5 kcal mol −1 of experiment, respectively. However, the agreement for HCN (with an established p K a) and HOONO is much worse and the calculated results suggest that the effect of the directly interacting solvent shells around HCN and HOONO are quite different from those around HONO 2, HONO, or HNO in terms of the solution phase acidity. Contrary to the view that HNO is an acid in aqueous solution, the p K a is estimated to be between 10 and 13 for HNO consistent with the latest experimental result. This suggests that the behavior of HNO in biological systems warrants further investigation as it is not an acid as has previously been accepted.

Accurate multireference calculations of the electron affinity of NO, BO and O 2

We report a systematic investigation of the adiabatic electron affinities (EA) of BO, NO and O 2 using a specifically adapted massively parallel version of the configuration-selective configuration interaction method (MRCI) which permits the explicit treatment of the most important triple and quadruple excitations (TQ). We find the EA( BO)=2.52 eV , EA( NO)=0.015 eV and EA( O 2)=0.39 eV in good agreement with experimental results. We elucidate the physical mechanism that is responsible for the failure of standard MRCI to quantitatively describe the EA of oxygen containing molecules.

Trends in ground and excited state electron affinities of group 14, 15, and 16 mixed diatomic anions: a computational study

The title diatomic anions have been investigated using the CAS-ACPF method and highly extended cc-pVQZ basis sets. CN and the homologue species have rather high electron affinities and especially the heavier congeners like SiAs−, GeP−, and GeAs− possess eight bound negative ion states, which belong to three different valence electron configurations. The diatomics containing group 14 and group 16 atoms exhibit rather small electron affinities, such as 0.036 eV and 0.14 eV for SiO and GeO, respectively. CS−, CSe−, SiO−, and GeO− are found to support dipole-bound anion states with electron affinities on the order of 0.01 eV. The electron affinity of NO is very small, whereas those of the heavier homologues are from close to 1 up to 1.6 eV. NS− and PO− possess at least an excited 1Δ state, whereas NSe−, PS−, PSe−, AsO−, AsS−, and AsSe− own two excited anion states, 1Δ and 1Σ+.

The electron affinities of NO and O2

In the 1970s, experimental values of the EA of O2 and NO clustered around two values, 0.43 and 0.9eV for O2 and 0.025 and 0.8eV for NO. We report new ground state adiabatic electron affinities (AEA), AEA-X: NO; 0.84±0.05 and O2; 0.9±0.05eV. Excited state EA, AEA∗ for spin orbital coupling states of NO are 0.27 and 0.25±0.02eV. The activation energies for thermal electron attachment to the X state are both 0.8±0.05eV. These were obtained by a least squares analysis of electron capture detector data using a two state model incorporating other literature data and their random uncertainties, including AEA, NO, 0.85±0.08eV and AEA∗ O2; 0.45 and 0.43±0.01eV. Morse Potential energy curves illustrate the assignments.

An accurate ab initio calculation of the electron affinity of NO

Potential energy curves for NO and NO − were calculated at the QCISD, QCISD(T), CCSD and CCSD(T) levels using aug-cc-pVDZ and aug-cc-pVTZ basis sets. The curves were fit with a modified Morse potential and rovibrational eigenvalues were extracted using TRIATOM software. The electron affinity of NO and the spectroscopic constants of both species were then determined. Better than 97% accuracy for the electron affinity was obtained for the QCISD, QCISD(T) and CCSD(T) techniques combined with the aug-cc-pVTZ basis set. It was determined that NO − is stable by virtue of zero-point energy only.

Formation of NO− following electron attachment to NO clusters

Low-energy (0–1 eV) electron attachment to NO clusters is studied with high-energy resolution (15 meV, FWHM). The dominant signal is NO− which has not been observed in previous Rydberg electron transfer studies to NO clusters. The relative cross-section for NO− formation shows a sharp peak close to 0 eV and a series of further weak peaks with a spacing of about 190 meV. The `0 eV' peak is ascribed to `s-wave capture' by the entire target cluster. Due to the low adiabatic electron affinity of NO (26 meV), NO− cannot be the result of an evaporative attachment reaction. It is suggested that neutral products like N2, via the strongly bound (ONNO)− intermediate, are involved. The weak structures are tentatively assigned as arising from transitions to vibrational excited states of solvated NO−.

Lattice energies of alkali metal nitrates and related thermodynamic properties

Abstract Correlations between the viscosity B-coefficient of the Jones-Dole equation for aqueous solutions of alkali metal salts and the enthalpy of hydration of the gaseous monatomic constituent ions have been established. The assumption that corresponding behaviour applies to alkali metal nitrates appears justified, and the standard enthalpies of solution of the gaseous ions M+(g) and NO3(g) have been estimated and used to derive the lattice energies of MNO3(c) [M = Li, Na, K, Rb, Cs]. Total lattice potential energies of the salt are (in kJ mol−1) LiNO3, 848; NaNO3, 755; KNO3, 685; RbNO., 662; CsNO3, 648. By use of such results in conjunction with other thermochemical data, the electron affinity of NO 3(g) has been evaluated, Euo− 3 = 3 98 ± 0 25 eV; this magnitude agrees satisfactorily with recent experimental results.

Molecular electron affinities from collisional ionization of cesium. I. NO, NO2, and N2O

The relative cross sections for the production of parent negative ions and O− fragment ions resulting from collisions of fast cesium atoms with Maxwellian target gases of NO, NO2, and N2O have been studied as a function of the incident cesium beam energy from 0 to ≈40 eV. A charge exchange source is used to produce the atomic cesium beam, and the energy distribution of the cesium beam is determined by a time-of-flight analysis. A time-of-flight mass spectrometer employing ion counting techniques is used to identify the masses of the ions. Measurements of the thresholds for the charge exchange reactions yield accurate lower limits to the electron affinities of NO, NO2, and N2O of 0.1 ± 0.1, 2.5 ± 0.1, and − 0.15 ± 0.1 eV, respectively. The tailing of the cross section at threshold due to Doppler motion of the target gas is accounted for by a mathematical unfolding procedure.

Electron affinities from endothermic negative-ion charge-transfer reactions, NO 2 and SF 6

Electron-transfer reactions of negative ions were studied Cross sections as a function of translational energy are and for Cl − with SF 6. The electron affinities of NO 2 ⪢⪢ served for these endothermic reaction. The Production of SF shown to result from scarverging of thermal secondary electron.

Additional flowing afterglow measurements of negative ion reactions of D-region interest

Some additional negative ion reactions of possible D-region importance have been measured in the ESSA flowing afterglow system at 300°K. It has been found that NO 3 − does not react with atomic oxygen or atomic nitrogen with a rate constant as large as 10 −11 cm 3/sec. The electron affinity of NO 3 is found to be greater than that of NO 2 by more than 0.9 eV. It is pointed out that conversion of O 2 − to O 4 − followed by subsequent reactions of the O 4 − may play an important role in D-region negative ion chemistry. Rate constants for the reaction of O 4 − with NO, CO 2 and O are reported. The reaction of O 4 − with CO 2 produces CO 4 −. Rate constants for the reactions of CO 4 − with NO and O are reported.

Ionization Potentials of Molecules and Free Radicals and Appearance Potentials by Electron Impact in the Mass Spectrometer

An improved method of measuring ionization efficiency (I.E.) curves by the retarding potential difference technique in the mass spectrometer (to ∼one ion/sec at onset) gives ionization potentials which agree within ± 0.02 eV of spectroscopic values and ± 0.03 eV of photoionization. Ionization potentials I have been measured for the following free radicals (eV): CH3, 9.87; C2H5, 8.34; n-C3H7, 8.13; i-C3H7, 7.57; n-C4H9, 8.01; C2H5O, 9.11; n-C3H7O, 9.20; i-C3H7O, 9.20; n-C4H9O, 9.22. Appearance potentials V have been measured for R+/RX, where R=CH3, C2H5, n-C3H7, n-C4H9 and X=H, Cl, Br, I, and OR; also for RO+/ROX where R=C2H5, i-C3H7, n-C4H9 and X=H, NO, and R; also for I+/n-C4H9I, NO+/C2H5ONO, NO+/n-C4H9ONO, and C3H6D+/CH3CD2CH3. Values of ΔHf(R+), ΔHf(RO+), D(R−X), and D(RO−X) are reported as well as electron affinities of NO, C2H5O, n-C3H7O, i-C3H7O, and n-C4H9O. Whenever two or more independent measurements of V provide the same ΔHf or D, agreement is satisfactory. The linearity of onsets does not correlate with photoionization efficiency curves according to present threshold theory. The “breaks” in I.E. curves do yield thermochemically consistent results.

Lattice energies and related properties derived using lyotropic numbers

The linear relationship between hydration heat and lyotropic number has been employed to obtain combined ion-hydration heats of alkali metal cations with the anions, nitrate, nitrite, perchlorate, chlorate, bromate, iodate and the thiocyanate. These values have been employed in conjunction with heat of solution data to derive lattice energies. Other magnitudes, which have been computed, include enthalpies of gaseous anions, anion hydration heats, and the electron affinities of NO 2, NO 3, ClO 3 and ClO 4. The fact that lyotropic numbers indicate different ionic field strengths is discussed.