Detachment Energies Research Articles

Relativistic Semistochastic Heat-Bath Configuration Interaction

In this work we present the extension of semistochastic heat-bath configuration interaction (SHCI) to work with any two-component and four-component Hamiltonian. The vertical detachment energy (VDE) of AuH2- and zero-field splitting (ZFS) of NpO22+ is calculated by correlating more than 100 spinors in both cases. This work demonstrates the capability of SHCI to treat problems where both relativistic effect and electron correlation are important.

Investigation of the Structures and Chemical Bonding of Mn2Ge6- and Mn2Ge7- Clusters via Anion Photoelectron Spectroscopy and Theoretical Calculations.

We present joint anion photoelectron spectroscopy and theoretical studies for Mn2Ge6- and Mn2Ge7-. Experimental results show that Mn2Ge6- and Mn2Ge7- have vertical electron detachment energies of 2.58 ± 0.08 and 2.88 ± 0.08 eV, respectively. Both Mn2Ge6- and Mn2Ge6 have Cs symmetric structures with a Mn atom attached to a pentagonal bipyramid MnGe6. Both Mn2Ge7- and Mn2Ge7 have C2v symmetric structures, which can be considered as two Mn2Ge4 tetragonal bipyramids sharing a MnGeMn face. According to chemical bonding analyses, Mn2Ge6 could be considered as a (MnII)(MnGe62-) complex. Theoretical calculations predict that the extension of Mn2Ge7 to Mn2nGe4n+3 may be able to produce a new type of Mn-doped germanium nanostructure.

Electron Propagator Theory of Vertical Electron Detachment Energies of Anions: Benchmarks and Applications to Nucleotides

A new generation of ab initio electron-propagator self-energy approximations that are free of adjustable parameters is tested on a benchmark set of 55 vertical electron detachment energies of closed-shell anions. Comparisons with older self-energy approximations indicate that several new methods that make the diagonal self-energy approximation in the canonical Hartree-Fock orbital basis provide superior accuracy and computational efficiency. These methods and their acronyms, mean absolute errors (in eV), and arithmetic bottlenecks expressed in terms of occupied (O) and virtual (V) orbitals are the opposite-spin, non-Dyson, diagonal second-order method (os-nD-D2, 0.2, OV2), the approximately renormalized quasiparticle third-order method (Q3+, 0.15, O2V3) and the approximately renormalized, non-Dyson, linear, third-order method (nD-L3+, 0.1, OV4). The Brueckner doubles with triple field operators (BD-T1) nondiagonal electron-propagator method provides such close agreement with coupled-cluster single, double, and perturbative triple replacement total energy differences that it may be used as an alternative means of obtaining standard data. The new methods with diagonal self-energy matrices are the foundation of a composite procedure for estimating basis-set effects. This model produces accurate predictions and clear interpretations based on Dyson orbitals for the photoelectron spectra of the nucleotides found in DNA.

A DMRG-CASPT2 investigation on the electronic states of NiSin−/0/+ (n = 1–3) clusters

The electronic states of NiSin−/0/+ (n = 1–3) clusters were studied using the DFT, RASPT2, and DMRG-CASPT2 methods. The DMRG-CASPT2 approach increases the complete active space to 18, 20, and 23 orbitals for NiSin−/0/+ (n = 1–3) clusters to attain accurate energies. The leading configurations, bond distances, vibrational frequencies, and relative energies of the electronic states of NiSin−/0/+ (n = 1–3) clusters are presented. The electron detachment energies of the anionic and neutral clusters are determined. The simulation of the Franck-Condon factors for the transition from the anionic to the neutral ground state within the NiSi3−/0 clusters reveals intense vibrational progressions.

Keys to improve the efficiency of nanoparticle‐stabilized foam injection based on influential mechanisms

AbstractThe effect of the existence of nanoparticles on foam stability, foamability, and the oil recovery factor (RF) has been studied experimentally, and influential phenomena and mechanisms have been examined. A sequence of experiments, including, ‘foam bulk‐static experiments’, ‘surface tension (ST) measurements,’ and ‘micromodel foam flood,’ were designed and then implemented to study the foam behaviour in two foam systems: (1) anionic‐nanoparticles + cationic‐surfactant and (2) anionic‐nanoparticles + anionic‐surfactant. This study provides a comprehensive insight into the mechanisms affecting the stability of nanoparticle‐stabilized foam. Also, despite previous studies, the effect of Marangoni flow on nanoparticle‐stabilized foam has been discussed briefly. Results show that the interactions of effective mechanisms work differently in the two series. In the like‐charge system, surfactant molecules accumulate in the interface of lamellas due to repulsive forces; therefore, stability and foamability improve as surface tension and molecular diffusion reduce. Additionally, Marangoni flow restitutes the negative impact of gravity drainage. In the unlike‐charge system, observations illustrate that nanoparticles reach the interface. The presence of nanoparticles at the interface increases detachment energy significantly, and as a result, the stability is boosted. The accumulation of nanoparticles in the interface changes it to a solid‐like surface with limited diffusibility and viscosity. Although Marangoni flow is lost, reducing molecular diffusion improves foam stability. Flooding tests show that foam stability increment improves sweep efficiency at near‐wellbore areas even when foamability is weak. Finally, it can be claimed that in the unlike‐charge system, the sweep efficiency and foam stability increase to a greater extent.

Absolute Electronic Energetics and Quantitative Work Functions of Liquids from Photoelectron Spectroscopy.

ConspectusLiquid-jet photoelectron spectroscopy (LJ-PES) enabled a breakthrough in the experimental study of the electronic structure of liquid water, aqueous solutions, and volatile liquids more generally. The novelty of this technique, dating back over 25 years, lies in stabilizing a continuous, micron-diameter LJ in a vacuum environment to enable PES studies. A key quantity in PES is the most probable energy associated with vertical promotion of an electron into vacuum: the vertical ionization energy, VIE, for neutrals and cations, or vertical detachment energy, VDE, for anions. These quantities can be used to identify species, their chemical states and bonding environments, and their structural properties in solution. The ability to accurately measure VIEs and VDEs is correspondingly crucial. An associated principal challenge is the determination of these quantities with respect to well-defined energy references. Only with recently developed methods are such measurements routinely and generally viable for liquids. Practically, these methods involve the application of condensed-matter concepts to the acquisition of photoelectron (PE) spectra from liquid samples, rather than solely relying on molecular-physics treatments that have been commonly implemented since the first LJ-PES experiments. This includes explicit consideration of the traversal of electrons to and through the liquid's surface, prior to free-electron detection. Our approach to measuring VIEs and VDEs with respect to the liquid vacuum level specifically involves detecting the lowest-energy electrons emitted from the sample, which have barely enough energy to surmount the surface potential and accumulate in the low-energy tail of the liquid-phase spectrum. By applying a sufficient bias potential to the liquid sample, this low-energy spectral tail can generally be exposed, with its sharp, low-energy cutoff revealing the genuine kinetic-energy-zero in a measured spectrum, independent of any perturbing intrinsic or extrinsic potentials in the experiment. Together with a precisely known ionizing photon energy, this feature enables the straightforward determination of VIEs or VDEs, with respect to the liquid-phase vacuum level, from any PE feature of interest. Furthermore, by additionally determining solution-phase VIEs and VDEs with respect to the common equilibrated energy level in condensed matter, the Fermi level─the generally implemented reference energy in solid-state PES─solution work functions, eΦ, and liquid-vacuum surface dipole effects can be quantified. With LJs, the Fermi level can only be properly accessed by controlling unwanted surface charging and all other extrinsic potentials, which lead to energy shifts of all PE features and preclude access to accurate electronic energetics. More specifically, conditions must be engineered to minimize all undesirable potentials, while maintaining the equilibrated, intrinsic (contact) potential difference between the sample and apparatus. The establishment of these liquid-phase, accurate energy-referencing protocols importantly enables VIE and VDE determinations from near-arbitrary solutions and the quantitative distinction between bulk electronic structure and interfacial effects. We will review and exemplify these protocols for liquid water and several exemplary aqueous solutions here, with a focus on the lowest-ionization- or lowest-detachment-energy PE peaks, which importantly relate to the oxidative stabilities of aqueous-phase species.

Hydrogen Bonding versus Halogen Bonding: Spectroscopic Investigation of Gas-Phase Complexes Involving Bromide and Chloromethanes.

Hydrogen bonding and halogen bonding are important non-covalent interactions that are known to occur in large molecular systems, such as in proteins and crystal structures. Although these interactions are important on a large scale, studying hydrogen and halogen bonding in small, gas-phase chemical species allows for the binding strengths to be determined and compared at a fundamental level. In this study, anion photoelectron spectra are presented for the gas-phase complexes involving bromide and the four chloromethanes, CH3 Cl, CH2 Cl2 , CHCl3 , and CCl4 . The stabilisation energy and electron binding energy associated with each complex are determined experimentally, and the spectra are rationalised by high-level CCSD(T) calculations to determine the non-covalent interactions binding the complexes. These calculations involve nucleophilic bromide and electrophilic bromine interactions with chloromethanes, where the binding motifs, dissociation energies and vertical detachment energies are compared in terms of hydrogen bonding and halogen bonding.

Structures and bonding properties of lithium polysulfide clusters LiSn-/0 (n = 3-5) and Li2S4-/0: size-selected anion photoelectron spectroscopy and theoretical calculations.

The structures and bonding properties of several lithium polysulfide clusters LiSn-/0 (n = 3-5) and Li2S4-/0 were investigated by size-selected anion photoelectron spectroscopy coupled with quantum chemistry calculations. The vertical detachment energies of LiS3-, LiS4-, and LiS5- were estimated to be 2.17 ± 0.08, 3.30 ± 0.08 and 3.66 ± 0.08 eV, respectively, and that of Li2S4- was estimated to be 3.21 ± 0.08 eV. It is found that LiS3- and LiS3 have planar quadrilateral structures, and LiS4- and LiS4 have distorted five-membered ring structures. LiS5- has a distorted six-membered ring structure while neutral LiS5 has a book-shaped structure. The lowest-lying structure of Li2S4- can be viewed as a S2 unit connecting to the Li-Li edge of a Li2S2 tetrahedron. The lowest-lying structure of neutral Li2S4 can be viewed as a S2 unit connecting to the S atoms of a Li2S2 quadrilateral. The natural population analysis (NPA) and electron localization function (ELF) analyses show that the excess electron of LiSn- is mainly localized over the sulfur chains, especially on the S atoms interacting with Li, thus, the most stable structures of LiSn- can be regarded as a Li+ cation interacting with a Sn2- dianion. The results may be useful for understanding the formation of lithium polysulfides in lithium sulfur batteries.

An ab initio study on the stability of isolated phosphaalkene synthons.

Using ab initio methods and flexible basis sets, we examined the electronic, geometric, and thermodynamic stabilities of selected phosphaalkene synthons matching the (PCR2)- formula (R = H, CH3, C6H5, C6F5, and Mes). All isolated synthons considered were found to be electronically stable and susceptible to neither fragmentation nor isomerization processes. The structures corresponding to the most stable isomers of the studied phosphaalkene synthons contain a PC double-bond (whose presence was confirmed by natural bond orbital occupancies of σ(P-C) and π(P-C) approaching 2 electrons) and two R substituents connected to the carbon atom in either (PCR2)- (for R = H, CH3, C6H5, and Mes) or (PCF-R-R)- (for R = C6F5) manner. Vertical electron detachment energies (spanning the 0.924-3.118 eV range) characterizing the phosphaalkene synthons were predicted and discussed.

Excess-electron capture and energy transfer to bulk water for aqueous DNA nucleotide.

We performed QM/MM simulations to investigate excess-electron attachment to four aqueous DNA nucleotide anions (dRT-). The negative QM/MM vertical electron affinities (-0.86 to -0.59 eV) reveal that aqueous dRT- anions improbably capture the excess electron near 0 eV. Comparing with the calculations in the gas phase and without the background charges, it can be found that first-shell water molecules have a larger contribution to the promotion of the ability of the excess-electron capture and the bulk-water polarization has a small effect on vertical electron affinities. The phosphate group hampers the attachment of the very low-energy excess electron to aqueous dRT-. The large adiabatic electron affinities (1.45-1.96 eV) and vertical detachment energies (1.92-2.44 eV) reveal that stable dRT2- dianions could be formed after dRT- anions catch the higher-energy excess electron (>0.59 eV). We computed the energy changes in the dRT2- structural relaxations. The QM-region conformational changes cause small energy alterations (-0.28 to 0.35 eV). The QM/MM energy decreases are 2.31-2.73 eV which mainly come from QM computations (3.49-4.00 eV) embedded in the background charges. The analysis of excess-electron distributions indicates that the polarization of bulk water and structural relaxations of dianions induce the excess-electron redistributions in the QM region and produce large QM-energy decreases. The MM energy changes are -1.27 to -1.11 eV for four aqueous dianions. The negative values demonstrate that the energy of the MM region would increase in dRT2- structural relaxations. In contrast with the values of the polarized QM computations, about 30% of the energy released by the QM region is transferred to bulk water in the MM region. The large energy dissipation probably suppresses DNA damage by the low-energy electron.

Prediction of the structures and heats of formation of MO2, MO3, and M2O5 for M = V, Nb, Ta, Pa.

Structures for the mono-, di-, and tri-bridge isomers of M2O5 as well as those for the MO2 and MO3 fragments for M = V, Nb, Ta, and Pa were optimized at the density functional theory (DFT) level. Single point CCSD(T) calculations extrapolated to the complete basis set (CBS) limit at the DFT geometries were used to predict the energetics. The lowest energy dimer isomer was the di-bridge for M = V and Nb and the tri-bridge for M = Ta and Pa. The di-bridge isomers were predicted to be composed of MO2+ and MO3- fragments, whereas the mono- and tri-bridge are two MO2+ fragments linked by an O2-. The heats of formation of M2O5 dimers, as well as MO2 and MO3 neutral and ionic species were predicted using the Feller-Peterson-Dixon (FPD) approach. The heats of formation of the MF5 species were calculated to provide additional benchmarks. Dimerization energies to form the M2O5 dimers are predicted to become more negative going down group 5 and range from -29 to -45 kcal mol-1. The ionization energies (IEs) for VO2 and TaO2 are essentially the same at 8.75 eV whereas the IEs for NbO2 and PaO2 are 8.10 and 6.25 eV, respectively. The predicted adiabatic electron affinities (AEAs) range from 3.75 eV to 4.45 eV for the MO3 species and vertical detachment energies from 4.21 to 4.59 eV for MO3-. The calculated MO bond dissociation energies increase from 143 kcal mol-1 for M = V to ∼170 kcal mol-1 for M = Nb and Ta to ∼200 kcal mol-1 for M = Pa. The M-O bond dissociation energies are all similar ranging from 97 to 107 kcal mol-1. Natural bond analysis provided insights into the types of chemical bonds in terms of their ionic character. Pa2O5 is predicted to behave like an actinyl species dominated by the interactions of approximately linear PaO2+ groups.

Low-Energy Shape Resonances of a Nucleobase in Water.

When high-energy radiation passes through aqueous material, low-energy electrons are produced which cause DNA damage. Electronic states of anionic nucleobases have been suggested as an entrance channel to capture the electron. However, identifying these electronic resonances have been restricted to gas-phase electron-nucleobase studies and offer limited insight into the resonances available within the aqueous environment of DNA. Here, resonance and detachment energies of the micro-hydrated uracil pyrimidine nucleobase anion are determined by two-dimensional photoelectron spectroscopy and are shown to extrapolate linearly with cluster size. This extrapolation allows the corresponding resonance and detachment energies to be determined for uracil in aqueous solution as well as the reorganization energy associated with electron capture. Two shape resonances are clearly identified that can capture low-energy electrons and subsequently form the radical anion by solvent stabilization and internal conversion to the ground electronic state. The resonances and their dynamics probed here are the nucleobase-centered doorway states for low-energy electron capture and damage in DNA.

Low‐lying states of FeSin−/0/+ (n = 1‐2) clusters from DMRG‐CASPT2 calculations

AbstractThe electronic states of FeSin−/0/+ (n = 1‐2) clusters have been investigated with DFT, CASPT2, and DMRG‐CASPT2 methods. By using relatively large active spaces, the DMRG‐CASPT2 method is found to provide highly accurate relative energies for the various relevant electronic states. Leading configurations, bond distances, harmonic vibrational frequencies, and relative energies for the low‐lying states of the title clusters are reported. Electron detachment energies for the ground states of the anionic and neutral clusters were estimated at the DMRG‐CASPT2 level. Franck‐Condon factor simulations were performed for transitions from the anionic ground state to the neutral ground state and from the neutral ground state to the cationic ground state with the purpose to produce the vibrational progressions.

Water activation and splitting by single anionic iridium atoms.

Mass spectrometric analysis of anionic products that result from interacting Ir- with H2O shows the efficient generation of [Ir(H2O)]- complexes and IrO- molecular anions. Anion photoelectron spectra of [Ir(H2O)]-, formed under various source conditions, exhibit spectral features that are due to three different forms of the complex: the solvated anion-molecule complex, Ir-(H2O), as well as the intermediates, [H-Ir-OH]- and [H2-Ir-O]-, where one and two O-H bonds have been broken, respectively. The measured and calculated vertical detachment energy values are in good agreement and, thus, support identification of all three types of isomers. The calculated reaction pathway shows that the overall reaction Ir- + H2O → IrO- + H2 is exothermic. Two minimum energy crossing points were found, which shuttle intermediates and products between singlet and triplet potential surfaces. This study presents the first example of water activation and splitting by single Ir- anions.

Theoretical and Experimental Study of the Spectroscopy and Thermochemistry of UC+/0/.

A combination of high-level ab initio calculations and anion photoelectron detachment (PD) measurements is reported for the UC, UC-, and UC+ molecules. To better compare the theoretical values with the experimental photoelectron spectrum (PES), a value of 1.493 eV for the adiabatic electron affinity (AEA) of UC was calculated at the Feller-Peterson-Dixon (FPD) level. The lowest vertical detachment energy (VDE) is predicted to be 1.500 eV compared to the experimental value of 1.487 ± 0.035 eV. A shoulder to lower energy in the experimental PD spectrum with the 355 nm laser can be assigned to a combination of low-lying excited states of UC- and excited vibrational states. The VDEs calculated for the low-lying excited electronic states of UC at the SO-CASPT2 level are consistent with the observed additional electron binding energies at 1.990, 2.112, 2.316, and 3.760 eV. Potential energy curves for the Ω states and the associated spectroscopic properties are also reported. Compared to UN and UN+, the bond dissociation energy (BDE) of UC (411.3 kJ/mol) is predicted to be considerably lower. The natural bond orbitals (NBO) calculations show that the UC0/+/- molecules have a bond order of 2.5 with their ground-state configuration arising from changes in the oxidation state of the U atom in terms of the 7s orbital occupation: UC (5f27s1), UC- (5f27s2), and UC+ (5f27s0). The behavior of the UN and UC sequence of molecules and anions differs from the corresponding sequences for UO and UF.

Bridging Electrochemistry and Photoelectron Spectroscopy in the Context of Birch Reduction: Detachment Energies and Redox Potentials of Electron, Dielectron, and Benzene Radical Anion in Liquid Ammonia.

Birch reduction is a time-proven way to hydrogenate aromatic hydrocarbons (such as benzene), which relies on the reducing power of electrons released from alkali metals into liquid ammonia. We have succeeded to characterize the key intermediates of the Birch reduction process─the solvated electron and dielectron and the benzene radical anion─using cyclic voltammetry and photoelectron spectroscopy, aided by electronic structure calculations. In this way, we not only quantify the electron binding energies of these species, which are decisive for the mechanism of the reaction, but also use Birch reduction as a case study to directly connect the two seemingly unrelated experimental techniques.

UV Photoelectron Spectroscopy of Aqueous Solutions.

ConspectusKnowledge of the electronic structure of an aqueous solution is a prerequisite to understanding its chemical and biological reactivity and its response to light. One of the most direct ways of determining electronic structure is to use photoelectron spectroscopy to measure electron binding energies. Initially, photoelectron spectroscopy was restricted to the gas or solid phases due to the requirement for high vacuum to minimize inelastic scattering of the emitted electrons. The introduction of liquid-jets and their combination with intense X-ray sources at synchrotrons in the late 1990s expanded the scope of photoelectron spectroscopy to include liquids. Liquid-jet photoelectron spectroscopy is now an active research field involving a growing number of research groups. A limitation of X-ray photoelectron spectroscopy of aqueous solutions is the requirement to use solutes with reasonably high concentrations in order to obtain photoelectron spectra with adequate signal-to-noise after subtracting the spectrum of water. This has excluded most studies of organic molecules, which tend to be only weakly soluble. A solution to this problem is to use resonance-enhanced photoelectron spectroscopy with ultraviolet (UV) light pulses (hν ≲ 6 eV). However, the development of UV liquid-jet photoelectron spectroscopy has been hampered by a lack of quantitative understanding of inelastic scattering of low kinetic energy electrons (≲5 eV) and the impact on spectral lineshapes and positions.In this Account, we describe the key steps involved in the measurement of UV photoelectron spectra of aqueous solutions: photoionization/detachment, electron transport of low kinetic energy electrons through the conduction band, transmission through the water-vacuum interface, and transport through the spectrometer. We also explain the steps we take to record accurate UV photoelectron spectra of liquids with excellent signal-to-noise. We then describe how we have combined Monte Carlo simulations of electron scattering and spectral inversion with molecular dynamics simulations of depth profiles of organic solutes in aqueous solution to develop an efficient and widely applicable method for retrieving true UV photoelectron spectra of aqueous solutions. The huge potential of our experimental and spectral retrieval methods is illustrated using three examples. The first is a measurement of the vertical detachment energy of the green fluorescent protein chromophore, a sparingly soluble organic anion whose electronic structure underpins its fluorescence and photooxidation properties. The second is a measurement of the vertical ionization energy of liquid water, which has been the subject of discussion since the first X-ray photoelectron spectroscopy measurement in 1997. The third is a UV photoelectron spectroscopy study of the vertical ionization energy of aqueous phenol which demonstrates the possibility of retrieving true photoelectron spectra from measurements with contributions from components with different concentration profiles.

Self crosslinked admicelle-Fe3O4 Janus nanoparticle with high detachment energy to creat low-energy emulsified and ultra-stable Pickering emulsion

By skillfully manipulating self-assembly and self-crosslinking activities of sodium conjugated linoleate in a wax-emulsion approach, we design a route to synthesize Janus (self-crosslinked admicelle)-decorated nano-Fe3O4 (SCA-Fe3O4 nanoparticle). The SCA-Fe3O4 nanoparticle exhibits ultra-high stability against environmental stresses of temperature (25–90 °C), salinity (0.1–1.8 M) and pH (1.8–11.7) relying on its high detachment energy at the oil/water interface to create ultra-stable Pickering emulsions. On the other hand, it is possible to demulsify the ultra-stable emulsions by simultaneously providing an external magnetic field and acidic pH under gently stirring to switch on–off the emulsions. Furthermore, the SCA-Fe3O4 nanoparticle reduces the requirement for energy density of emulsification, and achieves a new energy-saving effect in Pickering emulsion preparation comparable to low-energy emulsification methods in nanoemulsion preparation. Therefore, this strategy has good prospects to create Janus structures of various inorganic nanoparticles by a facile synthesis on the surface of frozen wax spheres, and these Janus particles have potential applications in Pickering emulsifiers, interfacial catalysts, biomedicines, and other multifunctional materials due to their asymmetric structure, unique interfacial characteristics and simplified emulsification operation.

Au as a Surrogate for F: The Case of UAu6 vs UF6.

Here, anion photoelectron spectroscopy and first-principles quantum chemistry are used to demonstrate to what degree Au can act as a surrogate for F in UF6 and its anion. Unlike UF6, UAu6 exhibits strong ligand-ligand, i.e., Au-Au, interactions, resulting in three low-lying isomers, two of which are three-dimensional while the third isomer has a ring-like quasi two-dimensional structure. Additionally, all the UAu6 isomers have open-shell electrons, which in nearly all cases are localized on the central U atom. The adiabatic electron affinity and vertical detachment energy are measured to be 3.05 ± 0.05 and 3.28 ± 0.05 eV, respectively, and are in very good agreement with calculations.

Electronic Properties of UN and UN- from Photoelectron Spectroscopy and Correlated Molecular Orbital Theory.

The results of calculations of the properties of the anion UN- including electron detachment are described, which further expand our knowledge of this diatomic molecule. High-level electronic structure calculations were conducted for the UN and UN- diatomic molecules and compared to photoelectron spectroscopy measurements. The low-lying Ω states were obtained using multireference CASPT2 including spin-orbit effects up to ∼20,000 cm-1. At the Feller-Peterson-Dixon (FPD) level, the adiabatic electron affinity (AEA) of UN is estimated to be 1.402 eV and the vertical detachment energy (VDE) is 1.423 eV. The assignment of the UN excited states shows good agreement with the experimental results with a VDE of 1.424 eV. An Ω = 4 ground state was obtained for UN- which is mainly associated with the 3H ΛS state. Thermochemical calculations estimate a bond dissociation energy (BDE) for UN- (U- + N) of 665.9 kJ/mol, ∼15% larger than that of UN and UN+. The NBO analysis reveals U-N triple bonds for the UN, UN-, and UN+ species.