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This minireview presents the results that show the potential of molecular nitrogen fixation by carbonyl cluster compounds of platinum metals at room temperature and atmospheric pressure to produce ammonia or its derivatives. Although the main attention is given to processes with the participation of derivatives of platinum and palladium, it was demonstrated that molecular nitrogen fixation is characteristic of all the platinum metals, except osmium.

Cutting-edge research on graphite-like carbon nitride-based (g-C3N4) photocatalytic systems for molecular nitrogen fixation is summarized. The properties of modified g-C3N4 with grafted functional groups, structural defects (nitrogen or carbon vacancies), doped with nonmetals and metals, as well as g-C3N4-based binary and ternary composites with the participation of metals, their oxides, metalates, carbonates, hydrocarbons, and sulfides are discussed. The most promising areas of further research are outlined.

Molecular nitrogen (N2) has been long believed to be an inert gas. Recently in Nature Catalysis, Duan et al. reported that N2 could dramatically promote the catalytic performance of hydrodeoxygenation over ruthenium-based catalysts and that as-formed hydrogenated nitrogen species contributed to the reduction of the activation energy required for carbon-oxygen bond cleavage inside p-cresol.

Ice core gas records are an invaluable paleoclimatic archive. The three most abundant gases in air, nitrogen (N2), oxygen (O2), and argon (Ar), provide paleoclimatic information about both global and regional processes including tropical rainfall patterns and local surface temperature changes. We present a large dataset of elemental and isotopic ratios of N2, O2, and Ar (O2/N2, Ar/N2, δ15N, δ18O, & δ40Ar) from the South Pole Ice Core between 0 – 52,000 yr BP, with a focus on high precision δ15N and δ40Ar measurements between 5,000 – 32,000 yr BP. The unprecedented precision of our measurements allows us to use δ15Nexcess (= δ15N - δ40Ar/4) to reconstruct past temperature change at the South Pole. Although this proxy has been widely applied in Greenland, this is the first time it has been successfully applied to Antarctic ice and provides a valuable independent check on the more traditional water isotopes temperature proxy. We find good agreement between the two during the relatively stable climate of the glacial period and the Holocene. However the temperature reconstructions diverge during the deglaciation. We present several hypotheses that could explain the discrepancy and look to other emerging ice core temperature proxies to support our interpretation.

Denitrification and anaerobic ammonium oxidation (anammox) are important biological processes of the nitrogen cycle that help to preserve the global ecosystem. However, indiscriminate development and global population growth result in the discharge of large amounts of nitrogen species (e.g., via the Haber–Bosch process), particularly nitrogen oxides and ammonia, which cannot be fully digested by microorganisms and therefore accumulate in soil and water. Photocatalysts can promote the conversion of nitrogen oxides and ammonia to molecular nitrogen under the action of photogenerated electrons and holes, thus mimicking denitrifying and anammox bacteria, respectively. Herein, we review the biomimetic photocatalysts and photoelectrochemical cells used to convert aqueous and airborne nitrogen species to molecular nitrogen and shed light on the charge transfer mechanism that should be selectively controlled to favor the formation of molecular nitrogen over that of nitrogen-containing intermediates and by-products. Last but not least, we discuss the outlooks and perspectives of solar-powered molecular nitrogen recovery and suggest guidelines for the design of high-performance denitrification/anammox bacteria-like photocatalysts.

The possibility of the existence of nitrogen molecules with an even number of atoms of composition N4, N6, N8, and N10 has been discussed with the use of the QCISD and G3 quantum-chemical methods. From these data, a conclusion has been made that three new nitrogen allotropes with an even number of atoms in a molecule can exist, namely, N4 shaped as a rectangle and regular tetrahedron and N6 with a shape remotely resembling an “open book.” The bond lengths and bond and torsion angles in each of these molecules have been reported.

Great enhancement of molecular nitrogen luminescence in the afterglow of nitrogen-helium gas mixtures was observed at temperatures ≤ 10 K. The effect is explained by the increased efficiency of the recombination of nitrogen atoms and energy transfer from metastable nitrogen molecules and helium atoms to nitrogen molecules in the cold dense helium vapor.Great enhancement of molecular nitrogen luminescence in the afterglow of nitrogen-helium gas mixtures was observed at temperatures ≤ 10 K. The effect is explained by the increased efficiency of the recombination of nitrogen atoms and energy transfer from metastable nitrogen molecules and helium atoms to nitrogen molecules in the cold dense helium vapor.

The absolute population of the B3Πg state of molecular nitrogen is calculated from the intensity of electron-vibrational bands of the first positive system. The absolute population of the metastable A3Σu state of nitrogen molecules is calculated based on the solution of the balance equation. It is established that the population of the metastable state of molecular nitrogen increases with a decrease in the pressure and increase in the current intensity of the glow discharge. The results of determining the population of the A3Σu state of nitrogen molecules under conditions of simultaneous excitation of glow and vacuum arc discharges are presented.

In this work we studied optical spectra of thermoluminescence accompanying the destruction of collections of molecular nitrogen nanoclusters containing stabilized nitrogen, oxygen, and deuterium atoms. These collections of nanoclusters were formed by the injection of products of a radio-frequency discharge in deuterium-nitrogen-helium gas mixtures into bulk superfluid 4He. In the range from 200 to 1650 nm, the bands at 336 nm, 473 nm along with a new band at 1170 nm as well as the known bands of atomic nitrogen and oxygen, and bands of molecular nitrogen, oxygen, and NO were observed. These three bands were assigned to the emission of the ND radicals formed due to recombinations of nitrogen atoms in excited metastable states and deuterium atoms in the ground state during the destruction of ensembles of molecular nitrogen nanoclusters.

In this study, we present a crystal structure prediction and characterization for two novel single- and double-bonded nitrogen allotropes (denoted as CubN and DobN) bearing three-membered nitrogen cycles. These materials are ambient-pressure metastable robust solids with strong cohesive energies. Due to the presence of strained nitrogen cycles, these allotropes are high-lying phases, which retain high energy densities at least up to 200 GPa, when CubN becomes lower in energy than ζ-N2. The studied allotropes are indirect wide-bandgap semiconductors. A detailed spectral characterization of these materials is also presented herein. Due to their extremely high heats of formation and crystal densities, CubN and DobN demonstrate excellent detonation properties that are comparable to those of previously reported phases (cg-N and TrigN). Propulsive properties (including specific impulse and characteristic velocity) of CubN and DobN as solid monopropellants were also estimated. Thus, if synthesized, the present nitrogen allotropes will have great potential for practical applications and achieving fundamental knowledge about nitrogen as a chemical element.

A combined experimental and computational study is reported on a hitherto unrecognised single lanthanide catalyst for the breaking of molecular nitrogen and formation of ammonia at ambient temperature and low pressure. We combine in situ electrical conductance and electron diffraction measurements to track the conversion from the lanthanide metals to the insulating lanthanide nitrides. The efficiency of the conversion is then interpreted using $\mathrm{DFT}+U$ calculations, suggesting a molecular nitrogen dissociation pathway separate from that well established for transition metals. Finally, we show that exposure of the lanthanide surfaces to both molecular nitrogen and hydrogen results in the formation of ammonia.

Analysis of the distribution and genesis of nitrogen in salts and subsalt formation fluids in the Volga-Ural Basin makes it possible to distinguish two genetically distinct groups of subsalt fluids and corresponding two distinct sources of nitrogen. One of them includes calcium chloride bridnes, nitrogen-saturated oils, and nitrogen-bearing formation gases. The fluids of this group have δ15N > 0‰ and occur closer to the surface in the platform part of the basin. The other group comprises only oils saturated with CH4 and methane formation gases, and the fluids of the latter group likely have δ15N < 0‰ and were found near the margin of the platform, in the Ural Foredeep and near the Caspian depression. The first group with isotopically heavy nitrogen is supposedly formed by fluids remaining after the loss of volatile components during ancient metamorphism of the rocks, whereas the second group was likely generated by the volatiles released during the degassing of the same rocks.

Results of experiments on photodesorption of molecular nitrogen from the glass surface are presented. The study is performed in vacuum glass cells whose internal surface is illuminated by a powerful pulsed lamp. The dynamics of the nitrogen density in the cell due to photodesorption is studied with the use of a mass spectrometer and a vacuum ionization lamp. A qualitative comparison of experimental data with results predicted by a developed theoretical model is performed.

This work provides an insight into the generation of excited nitrogen species by allowing noble gases to interact both with one another and ambient air. He and Ar were utilized to generate the optimum selectivity process to create reactive nitrogen species. An optimum setting for the generation of excited molecular nitrogen species, based on their excited energy levels, was obtained when using a mixture of Ar-He at a ratio of 10:1. At that point, when a voltage of 27 kV is applied to the system, it reached the maximum efficiency for selectivity processes to occur which allowed for a greater non-radiative transfer of energy through the mixture of noble gas atoms and into the molecular nitrogen present in ambient air.

We have studied formation of molecular nitrogen under low-energy nitrogen bombardment in a range of compound semiconductors by synchrotron-based X-ray photoelectron spectroscopy (XPS) around N 1 s core-level and near-edge X-ray absorption fine structure (NEXAFS) around N K-edge. We have found interstitial molecular nitrogen, N 2 , in all samples under consideration. The presence of N 2 produces a sharp resonance in low-resolution NEXAFS spectra at around 400.8 eV, showing the characteristic vibrational fine structure in high-resolution measurements. At the same time, a new peak, shifted towards higher binding energies, emerges in all N 1 s photoemission spectra. We have found a shift of 7.6 eV for In-based compounds and 6.7 eV for Ga-based compounds. Our results demonstrate that NEXAFS and core-level XPS are complementary techniques that form a powerful combination for studying molecular nitrogen in compound semiconductors, such as GaSb, InSb, GaAs, InN, GaN or ZnO.

The adsorption of gas molecules at electrode–electrolyte interfaces is an important step in electrochemical reactions. Using molecular dynamics simulations, we investigate the adsorption of dissolved N2 in the electrical double layers (EDLs) of an aqueous electrolyte near planar and 1 nm radius spherical carbon electrodes. The adsorption of N2 is found to be overall enriched near neutral electrodes regardless of their surface curvature, although it can be locally enriched or depleted depending on the distance from the electrode surface. In comparison, the adsorption of N2 in the EDL near negatively charged electrodes is found to increase under a moderate surface charge density, but decrease under a high surface charge density, especially near a planar electrode. By analyzing the potential of mean force for dissolved N2, the solvent-induced effects are found to play important roles in influencing the adsorption of N2 in the EDLs. The adsorption behavior of N2 molecules, especially their dependence on the s...

Quasiclassical trajectories have been integrated to study the exchange reaction of molecular nitrogen in collisions with atomic nitrogen for temperatures over the range of 1273or = T (K)or = 10,000. A recently proposed potential energy surface for the ground A'' quartet state of the system has been employed. If compared to previous theoretical studies, the results of the present work show a higher reactivity due to a lower barrier, with a study of the effect of this height in the thermal rate constant being also performed. Vibrational energy transfer via chemical reaction and/or inelastic collisions are also studied.

The coexistence line of two high-pressure phases of solid nitrogen, molecular and polymeric cubic gauche (CG), has been predicted using two separate equations of state. The phase transition parameters, latent heat, volume, and entropy jumps, were calculated. At low temperatures, the predicted volume jump ΔV(P) is in agreement with recent experimental data; at elevated temperatures the P(T)-curve approaches the pressure maximum on the melting line.

The highly excited states of gerade symmetry in molecular nitrogen were investigated in a resonance enhanced XUV+Vis transition scheme. A two photon laser excitation study, with subsequent photo-ionization by a third laser pulse was reported. Tunable XUV laser light was generated by frequency doubling the output of a pulsed dye laser into ultraviolet in a KDP crystal, and subsequently frequency tripling the output ion xenon gas jet. Nineteen bands were observed and level energies were determine with an accuracy of ≈ 0.20 cm

Molecular nitrogen adsorption on single platinum and titanium nanoclusters is investigated by scanning tunneling microscopy and spectroscopy, including the use of an inverse scheme of spectroscopic measurements. Some regularities of the occurring processes are found.

Although molecular dinitrogen (N2) is widely used as a carrier or inert gas for many catalytic reactions, it is rarely considered as a catalytic promoter. Here, we report that N2 could be used to reduce the activation energy for catalytic hydrodeoxygenation over ruthenium-based catalysts. Specifically, we report a 4.3-fold activity increase in the catalytic hydrodeoxygenation of p-cresol to toluene over a titanium oxide supported ruthenium catalyst (Ru/TiO2) by simply introducing 6 bar N2 under batch conditions at 160 °C and 1 bar hydrogen. Detailed investigations indicate that N2 can be adsorbed and activated on the metallic ruthenium surface to form hydrogenated nitrogen species, which offer protic hydrogen to lower the activation energy of direct carbonaromatic–oxygen bond scission and the hydrogenation of hydroxy groups. Thus, by employing different ruthenium catalysts, including Ru/TiO2, Ru/Al2O3, Ru/ZrO2 and Ru/C, we demonstrate that N2 promotion of hydrodeoxygenation can be regarded as a general strategy. Due to its stability nitrogen is often employed as an inert gas during catalytic reactions. Now, a study shows that N2 can act as promoter for the catalytic hydrodeoxygenation of p-cresol on supported ruthenium catalysts through the formation of hydrogenated nitrogen species acting as a source of protic hydrogen.

High content of molecular nitrogen (N2) is one of the natural gas exploration risks in petroliferous basins where black shales act as source rocks of either hydrocarbon gas or molecular nitrogen. In this study, two overmature and one low-maturity shale samples and their kerogens were investigated to determine the generation characteristics of molecular nitrogen as well as methane and the differences in the release processes of inorganic nitrogen fixed in ammonium-bearing minerals and organic nitrogen bound in kerogen. The results illustrate that with increasing pyrolysis temperature, the yield of methane first increases and then decreases with an inflection temperature of 650 °C (EqVRo = 3.4%), whereas the yield of molecular nitrogen shows a continuous increase throughout the pyrolysis experiment. The molecular nitrogen during the stage of methane generation (i.e., EqVRo 3.4%). The results also reveal that at the experimental maxima of thermal maturity (EqVRo = 4.9%), the generation potential of inorganic molecular nitrogen (mg/g Ninorg) is much lower than that of organic molecular nitrogen (mg/g Norg), indicating that in our experiments the organic nitrogen in kerogen is more easily to be converted into molecular nitrogen than the inorganic nitrogen in ammonium-bearing minerals. All these results indicate that molecular nitrogen content in shale gas may change dramatically during thermal evolution, and source rocks with exceptionally high maturity and high abundance of organic nitrogen likely lead to a high molecular nitrogen risk, particularly in regions of poor preservation conditions of shale gas, which may be the main reasons for the high molecular nitrogen content in the Lower Cambrian shale gas in South China.

The isotopic compositions of N2 ( δ 15 N , ‰, atm) imply the geochemical origins of molecular nitrogen in natural gas accumulations, but the irregular variation of δ 15 N N 2 for most petroliferous basins puzzles scientists. We believe that this is due to multiple origins of N2 which are often mixed together and leads to the irregularities in gas pools. The four petroliferous basins, the West Siberian basins in Russia, the Yinggehai basin of China, the Californian Great Valley basin of USA and the Mid-European basin, have significantly different isotope characteristics of N2, which may provide insight into the isotope geochemical implications of N2 in natural gas accumulations. N2 with −19‰⩽ δ 15 N N 2 ⩽−10‰ may be from sedimentary organic matter at the immature and the early mature stage (Ro⩽0.6%). Values of −10‰ 15 N N 2 ⩽−2‰ may indicate that N2 originates from mature (including high mature) sedimentary organic matter (Ro≈0.6–2.0%). Values of −2‰ δ 15 N N 2 δ 15 N N 2 =0‰ and N2/Ar=38–84 suggest that the atmosphere is the origin. Values of +1‰⩽ δ 15 N N 2 δ 15 N N 2 =+4‰ is the feature of N2 from saltpeter in evaporites. Values of +4‰ δ 15 N N 2 ⩽+18‰ indicate that N2 maybe derived from post-mature sedimentary organic matter (Ro>2.0%).

A route to break molecular nitrogen (N2) under mild conditions is demonstrated by N2 gas cracking on, and incorporation into, lanthanide films. Successful growth of lanthanide nitride thin films, made by evaporation of lanthanides in a partial N2 atmosphere at room temperature and pressure as low as 10-4 Torr, is confirmed using X-ray diffraction. In-situ conductance measurements of pure lanthanide thin films exposed to N2 gas show an immediate surface reaction and a slower bulk reaction. Finally, we report partial reversal of the nitrogen incorporation in a lanthanide nitride by cycling vacuum and nitrogen conditions in the sample chamber.A route to break molecular nitrogen (N2) under mild conditions is demonstrated by N2 gas cracking on, and incorporation into, lanthanide films. Successful growth of lanthanide nitride thin films, made by evaporation of lanthanides in a partial N2 atmosphere at room temperature and pressure as low as 10-4 Torr, is confirmed using X-ray diffraction. Insitu conductance measurements of pure lanthanide thin films exposed to N2 gas show an immediate surface reaction and a slower bulk reaction. Finally, we report partial reversal of the nitrogen incorporation in a lanthanide nitride by cycling vacuum and nitrogen conditions in the sample chamber.

Direct synthesis of organo-nitrogen compounds from molecular nitrogen is a challenging subject in the chemistry of nitrogen fixation. Toward this direction, we have long been investigating novel chemical transformations of coordinated dinitrogen. Described herein are our recent results on (1) synthesis of nitrogen-heterocycles from molecular nitrogen via condensation reactions of hydrazido complexes wi th dialdehydes or their equivalents, (2) bimetallic arylation of molecular nitrogen by using reactions of anionic dinitrogen complexes with η 6 -fluoroarene complexes, and (3) catalytic silylation of molecular nitrogen.

The reactions of the cations CN+, HCN+, HCNH+, HC3N+, HC3NH+, H3+, H2O+, H3O+, N2+, CO+, HCO+, O2+, CO2+, HCO2+, and C2H2+ with atomic and molecular nitrogen have been characterized using a selected ion flow tube (SIFT) operating at room temperature. Rate coefficient and branching ratio data are reported for all ion–neutral reactions studied. Constraints arising from spin conservation considerations are found to be unimportant in cation-N atom processes.

The paper describes remarkable reactions of the direct synthesis of aromatic amines from molecular nitrogen. Two types of systems capable of inducing such reactions are considered in detail. The first type involves systems based on titanium compounds (Cp2TiCl2, Cp2TiPh2, CpTiCl3, TiCl4, Ti(OBu)4) and excess aryllithium reagents (PhLi, p-, m- and o-MeC6H4Li, α-C10H8Li, oPhC6H4Li) in ether. The second type is obtained by treating diaryltitanocenes Cp2TiAr2 (Ar = Ph, p- and m-MeC6H4) with metals of groups I and II (Li, Na, Mg) in ethereal media. In both cases the interaction with dinitrogen proceeds at room temperature and results in the formation of aromatic amines and ammonia after hydrolysis. The highest activity in amine production is displayed by the systems Cp2TiCl2 + PhLi in ether and Cp2TiPh2 + Li in THF. The mechanism of the reactions found is discussed.

Resonance structures corresponding to the (3sσ) 2 2 Σ + state in carbon monoxide at 10.044 eV and the (3sσ g ) 2 2 Σ g + state in nitrogen at 11.499 eV have been studied in elastic electron scattering over the range of scattering angle from 95° to 180°. A new magnetic angle-changing technique has been used in the measurements, which has enabled the first observation of these resonance structures at and close to 180°. The width of the 2 Σ + resonance in carbon monoxide has been determined to be 42±3 meV.

Direct synthesis of organo-nitrogen compounds from molecular nitrogen is a challenging subject in the chemistry of nitrogen fixation. Toward this direction, we have long been investigating novel chemical transformations of coordinated dinitrogen. Described herein are our recent results on (1) synthesis of nitrogen-heterocycles from molecular nitrogen via condensation reactions of hydrazido complexes wi th dialdehydes or their equivalents, (2) bimetallic arylation of molecular nitrogen by using reactions of anionic dinitrogen complexes with η 6 -fluoroarene complexes, and (3) catalytic silylation of molecular nitrogen.

The hydrazido(2-) complexes [WCl2(NNH2)(L)(PMe2Ph)2] (L = PMe2Ph, CO), derived from the dinitrogen complex cis-[W(N2)2(PMe2Ph)4] (1), reacted with β-diketones R1COCHR2COR3 (R1 = Me, But, Ph; R2 = H, Me; R3 = Me, Et, But, Ph) to afford a series of diazoalkane complexes [WCl2(NN=CR1CHR2COR3)(L)(PMe2Ph)2]. The detailed structure of cis,mer-[WCl2(NN=CMeCH2COPh)(PMe2Ph)3] has been determined by X-ray analyses. These diazoalkane complexes were treated with a KOH/EtOH mixture to produce pyrazoles in moderate yields, whereas the reaction of 1 with a MeCOCH2COPh/KOH/EtOH mixture resulted in the direct formation of 5-methyl-3-phenylpyrazole.

We have investigated the adsorption of nitrogen on Cr(110) at 100 K and have found strong evidence to support the existence for a weakly bound molecular state. We estimate that the heat of desorption for this molecular nitrogen state from Cr(110) is approximately 14 kJ/mol. Desorption from this state is completed by 155 K. This molecular nitrogen species is believed to be coadsorbed or is identical to the α-nitrogen state observed by previous photoemission studies.

A radiation-catalytic experiment of the fixation and reduction of molecular nitrogen has been carried out. The [WH 4 (dtpe) 2 ] complex was applied to fix molecular nitrogen in a γ-radiation field. Plots of the dependence of either the number of molecules of ammonia or hydrazine vs dose are presented. A mechanism for the radiation-catalytic fixation and reduction of molecular nitrogen using the [WH 4 (dtpe) 2 ] complex is suggested. The unusually high radiation yields of ammonia and hydrazine are explained as due to a cyclic process.

Recent measurements of the (e, 3-1e) fourfold differential cross sections for the double ionization of helium are here extended to more complex targets, namely neon, argon and molecular nitrogen. The previous observations of large angular shifts in the experimental fourfold differential cross section (4DCS) distributions with respect to the momentum transfer axis and the existence of structures in these distributions are found to similarly hold here. For the three investigated targets, the experimental data are compared with the kinematical analysis previously given to describe the second-order, 'two-step 2' (TS2) double ionization (DI) mechanism. Such a comparison confirms our interpretation which allows the observed shifts and structures in the intensity distributions to be mostly related to the 'two-step 2' mechanism, which is shown to predominate over the first-order 'shake-off' (SO) and 'two-step 1' (TS1) mechanisms under the present kinematics. The experimental data are also compared to the predictions of a first Born and second Born model, showing rather mixed agreement.

Incorporation of molecular nitrogen into organic compounds was realized using a catalytic amount of TiCl4 in the presence of excess TMSCl and Li under nitrogen.

The two molybdenum(IV) hydride complexes [MoH4(dppe)2][dppe = (C6H5)2 PCH2CH2P(C6H52] and [MoH4(dtpe)2] [dtpe =(o-CH3C6H4)2PCH2CH2P(o-CH3C6H4)2] were applied in a process of radiation-catalytic reduction of molecular nitrogen. The yields of ammonia and hydrazine were determined for different concentrations of these complexes in cyclohexane solutions. The mechanism of the reduction of molecular nitrogen by γ-radiation is suggested. It has also been discovered that the [MoH4(LL)2] complexes are useful in the process of radiation-catalytic fixation and reduction of nitrogen.

Hydride complexes of W(IV) with dpep (diphenylethylphosphine) and dpmp (diphenylmethylphosphine) were irradiated in thf+C6H12(1∶1) solutions, saturated with N2+H2(1∶3). Radiation yields of hydrazine, ammonia and amines were evaluated. The mechanism of reduction of molecular nitrogen is discussed.

The formations of molecular nitrogen and hydrogen complexes (η6-C6H6)-Cr(CO)2-L(L=N2 and H2) were observed via time-resolved infrared spectroscopy following 355nm laser photolysis of (η6-C6H6)Cr(CO)3 in the presence of N2 and H2 in gas phase. The rate constants for reactions of (η6-C6H6)-Cr(CO)2 with N2 with N2 and H2 were measured to be (1.4±0.1)×105 Torr-1s-1 and (2.6±0.1)×105 Torr-1s-1, respectively. The complexes (η6-C6H6)Cr(CO)2L (L=N2 and H2) have lifetimes longer than 1 ms in our experimental conditions implying the N2 and H2 binding energies in (η6-C6H6)Cr(CO)2 L (L=N2 and H2)>17 kcal mol-1.

Autoionization from vibrationally resolved core excited states is demonstrated, using nitrogen physisorbed on graphite. The results are compared to photoemission and x-ray absorption, and reveal an adsorption induced elongation of the internuclear separation in the 3${\mathrm{\ensuremath{\sigma}}}_{\mathit{g}}^{\mathrm{\ensuremath{-}}1}$ final state. It is demonstrated that it is only in the case of vibrationally selective excitation that the autoionization final states coincide with the photoemission final states.

The vacuum ultraviolet emission spectrum of molecular nitrogen, produced by a low pressure discharge, is investigated at high spectral resolution from 107.7 to 124.2nm. Band origins are reported for the 103 bands rotationally analyzed.

Nitrogen adsorption on thin iron films at 78 K and 195 K was studied measuring simultaneously the surface potential and pressure changes, and also by means of the TDMS method. The transition of the positively polarized nitrogen admolecules in the γ state into the negatively polarized admolecules in the α state is observed as surface potential transients. The negatively polarized molecular nitrogen deposit arising at 195 K is not a homogeneous one, but consists of two states α1 and α2 of different binding energy. The α1 state is characterized by an activation energy for desorption of 52 kJ mol , a frequency factor 1012 s−1 a sticki probability value of 10−6 to 10−7 at coverage 0.1 to 0.25 and a dipole moment 0.06 D. The dipole moment for the γ state reaches 0.25 D.

Synthesis of tetrahydroindole derivatives was realized from keto-alkyne using titanium-nitrogen complexes generated from Ti(OiPr)4, Li, and TMSCl. In this reaction, the electron-withdrawing group on the alkyne gave a good yield, and keto-alkynes having an aromatic ring on the alkyne also gave tetrahydroindole derivatives in good to moderate yields.

We studied the luminescence of molecular nitrogen nanoclusters containing stabilized nitrogen, oxygen, hydrogen, and deuterium atoms. Optical spectra were observed during the destruction of these ensembles of nanoclusters accompanied by a rapid release of chemical energy stored in the samples. Several interesting features were observed including a broad band near λ ≈ 360 nm, which was identified as emission corresponding to 2Ag→1Ag transition of N4(D2h) polymeric nitrogen. Also the sharp lines at λ ∼ 336 and 473 nm were observed, and their assignments to ND radicals are discussed.

The interaction of nitrogen molecules (N2) with the host lattice of compound semiconductors is investigated using first-principles density-functional calculations. In ZnO it is found that N2 causes localized states in the band gap either by forming an N2O molecule or by breaking a Zn-O bond. This mechanism contributes to the observed low nitrogen doping efficiency in ZnO. The appearance of localized states caused by N2 was also found in other semiconductors such as MgO and NaCl.