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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Photoabsorption and photoionization of N2 near the first ionization threshold

The photoabsorption and photoionization spectra of molecular nitrogen, N2, near the first ionisation threshold display numerous intense resonances that have not been satisfactorily assigned to date. Principal among these is a pair of broad resonances between 126,200 and 126,600 cm−1 commonly referred to as the ”cathedral” bands. Here, we present new double-resonance photoionization spectra in this region recorded via the 𝑎′′ 1Σ+ 𝑔,𝑣′=0 intermediate state as well as new high-resolution, vacuum-ultraviolet photoabsorption spectra of 14N2,14N15N, and 15N2 to provide additional insight into the assignment of these features. Progress towards a fully consistent interpretation of the existing data on these bands is discussed, and a route towards a comprehensive description of the N2 absorption spectrum up to the 𝐵 2Σ+ 𝑢 state of N+ 2 is proposed.

Nitrogen, vacuum ultraviolet absorption, photoioni↗
DOE OSTI2020

Materials Data on N2 by Materials Project

N2 is Magnesium structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is zero-dimensional and consists of two ammonia molecules. N is bonded in a 1-coordinate geometry to atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on N2 by Materials Project

N2 is gamma nitrogen structured and crystallizes in the tetragonal P4_2/mnm space group. The structure is zero-dimensional and consists of two nitrogen molecules. N is bonded in a single-bond geometry to one N atom. The N–N bond length is 1.11 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on N2 by Materials Project

N2 is Lonsdaleite structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is zero-dimensional and consists of two nitrogen molecules. N is bonded in a single-bond geometry to one N atom. The N–N bond length is 1.11 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on N2 by Materials Project

N2 crystallizes in the cubic P2_13 space group. The structure is zero-dimensional and consists of four ammonia molecules. N is bonded in a 1-coordinate geometry to atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on N2 by Materials Project

N2 is graphite-like structured and crystallizes in the cubic I2_13 space group. The structure is three-dimensional. N is bonded in a trigonal non-coplanar geometry to three equivalent N atoms. All N–N bond lengths are 1.41 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on N2 by Materials Project

N2 is beta Sn-like structured and crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. N is bonded to six equivalent N atoms to form a mixture of distorted edge, corner, and face-sharing NN6 pentagonal pyramids. There is four shorter (1.90 Å) and two longer (1.91 Å) N–N bond length.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on N2 by Materials Project

N2 is Cyanogen Chloride-derived structured and crystallizes in the orthorhombic Pmna space group. The structure is zero-dimensional and consists of four ammonia molecules and four triazane molecules.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on N2 by Materials Project

N2 is Copper structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. N is bonded to twelve equivalent N atoms to form a mixture of distorted face, edge, and corner-sharing NN12 cuboctahedra. All N–N bond lengths are 2.17 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Isomer-specific, Cryogenic Ion Vibrational Spectroscopy Investigation of D2-and N2- Tagged, Protonated Formic Acid Complexes Using Two Color, IR-IR Photobleaching

Here we analyze cryogenic ion vibrational spectra of tagged protonated formic acid (PFA) with electronic structure and anharmonic vibrational calculations to establish the isomers generated by electrospray ionization (ESI) followed by buffer gas cooling to ~25 K. Two isomers are identified (the trans form (E,Z) and the cis form (E,E)) and generated in comparable abundance despite the fact that the calculated E,E structure lies 6.40 kJ mol-1 above the E,Z form. A large (~60 kJ mol-1) barrier separates them such that the E,E form can be kinetically trapped upon cooling in the ion trap. The anticooperativity between the H-bonds of the OH groups is explored by measuring the shift in the D2-bound OH fundamental when a second D2 is attached. Both isomers are observed in the N2-tagged counterparts, displaying the expected red-shifted OH bands. These results indicate that ESI generates both isomers and both must be considered when analyzing cluster spectra based on the PFA core ion.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Design of AlGaN-Zn(Si,Ge)N2 quantum wells for high-efficiency ultraviolet light emitters

The effect of inserting a nm-scale layer of Zn(Si,Ge)N2 into an AlGaN quantum well structure designed for light emission in the wavelength range from 255 to 305 nm is investigated here. The enhanced confinement of the hole within the quantum well results in an enhancement of the overlap of the hole and electron wave functions, resulting in an enhancement of the radiative recombination rate. In this theoretical calculation, for emission at a 270 nm wavelength, the enhancement in the wavefunction overlap can reach a factor of 7 when compared to an AlGaN quantum well device specifically engineered for optimal emission at the identical wavelength. Increases of almost an order of magnitude in both the peak spontaneous emission intensity and the radiative recombination rate are predicted. The peak emission wavelength can be tuned from 255 to 305 nm by adjusting the width and/or the composition of the inserted layer. The proposed structures provide a route to higher efficiency ultraviolet practical light emitting diodes and lasers.

Physics↗
DOE OSTI2023

The Piezoresponse in WO3 Thin Films Due to N2-Filled Nanovoids Enrichment by Atom Probe Tomography

Tungsten trioxide (WO3) is a versatile n-type semiconductor with outstanding chromogenic properties highly used to fabricate sensors and electrochromic devices. We present a comprehensive experimental study related to piezoresponse with piezoelectric coefficient d33 = 35 pmV−1 on WO3 thin films ~200 nm deposited using RF-sputtering onto alumina (Al2O3) substrate with post-deposit annealing treatment of 400 °C in a 3% H2/N2-forming gas environment. X-ray diffraction (XRD) confirms a mixture of orthorhombic and tetragonal phases of WO3 with domains with different polarization orientations and hysteresis behavior as observed by piezoresponse force microscopy (PFM). Furthermore, using atom probe tomography (APT), the microstructure reveals the formation of N2-filled nanovoids that acts as strain centers producing a local deformation of the WO3 lattice into a non-centrosymmetric structure, which is related to piezoresponse observations.

36 MATERIALS SCIENCE↗