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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 577 records · Page 32
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

High‐Performance Fluorinated Fused‐Ring Electron Acceptor with 3D Stacking and Exciton/Charge Transport

Abstract A new fluorinated electron acceptor (FINIC) based on 6,6,12,12‐tetrakis(3‐fluoro‐4‐hexylphenyl)‐indacenobis(dithieno[3,2‐ b ;2 ′ ,3 ′ ‐ d ]thiophene) as the electron‐donating central core and 5,6‐difluoro‐3‐(1,1‐dicyanomethylene)‐1‐indanone as the electron‐deficient end groups is rationally designed and synthesized. FINIC shows similar absorption profile in dilute solution to the nonfluorinated analogue INIC. However, compared with INIC, FINIC film shows red‐shifted absorption, down‐shifted frontier molecular orbital energy levels, enhanced crystallinity, and more ordered molecular packing. Single‐crystal structure data show that FINIC molecules pack into closer 3D “network” motif through H‐bonding and π–π interaction, while INIC molecules pack into incompact “honeycomb” motif through only π–π stacking. Theoretical calculations reveal that FINIC has stronger electronic coupling and more molecular interactions than INIC. FINIC has higher electron mobilities in both horizontal and vertical directions than INIC. Moreover, FINIC and INIC support efficient 3D exciton transport. PBD‐SF/FINIC blend has a larger driving force for exciton splitting, more efficient charge transfer and photoinduced charge generation. Finally, the organic solar cells based on PBD‐SF/FINIC blend yield power conversion efficiency of 14.0%, far exceeding that of the PBD‐SF/INIC‐based devices (5.1%).

Dai, Shuixing↗
DOE OSTI2026

Effect of Solvent on the Local Structure, Dynamics, and Vibrational Density of States in Sn-BEA Zeolite

Lewis acid zeolites are attractive catalysts for epoxidation and biomass valorization, as they are highly active and selective in the liquid phase and can operate at or near ambient conditions. While a rich experimental literature exists on liquid-phase Lewis acid zeolite catalysis, our understanding of the molecular organization and solvent dynamics in the vicinity of Lewis acid sites with differing metal site speciation remains limited. In this work, we investigate the molecular coordination and diffusion of two common solvents (methanol and water) around the closed and open Sn-BEA zeolite active sites using molecular dynamics simulations with a machine-learned interatomic potential trained on ab initio molecular dynamics trajectories. Molecular dynamics simulations reveal that introducing active sites significantly enhances local order in the first and second solvation shells compared to the pure silica case. For methanol, both closed and open active sites are singly coordinated, while more than two water molecules coordinate the open site. In contrast to methanol, we observed that water molecules dissociate, leading to the formation of additional Sn-OH and silanol groups away from the active site. The diffusion coefficients of water and methanol are functions of the solvent population in the pore. Here, our work provides insights into how active site speciation in Lewis acid zeolites affects solvent coordination, diffusion, and vibrational signature. This information is foundational for catalyst design and optimization of liquid-phase catalytic processes in zeolites. It also demonstrates the suitability of machine-learned interatomic potentials for modeling reactive systems, enabling sufficiently long trajectories for appropriate statistical averaging.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Plasmon-Assisted Direct Interfacial Charge Transfer Enables Molecular Photodissociation on Metal Surfaces

Plasmonic photocatalysis is promising for driving reactions out of equilibrium, leading to enhanced rates and selectivity, but the energy and charge transfer mechanism at the interface remains to be explored. Here, we revisit visible-light plasmon-assisted photodissociation of dimethyl disulfide molecules (S–S bond cleavage) over single-crystalline silver and copper surfaces, using density functional theory calculations and the delta self-consistent field method. We investigate different excitation mechanisms and show that the direct intramolecular excitations, as suggested earlier to explain the experimental findings, cannot address the observed catalytic bond activation. Instead, the calculated excitations mediated by the metal Fermi level agree well with the threshold energy and maximum-yield energy in experiments and suggest that the reaction follows a direct interfacial charge transfer mechanism. Furthermore, we show that the excitation energy and the charge transfer can be modulated by introducing excess charges in the systems. Here, this study thus provides a fundamental understanding of interfacial charge transfer for driving plasmonic photocatalysis.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Electronic states and transitions of PrO and PrO + probed by threshold ionization spectroscopy and spin–orbit multiconfiguration perturbation theory

The precise ionization energy of praseodymium oxide (PrO) seeded in supersonic molecular beams is measured with mass-analyzed threshold ionization (MATI) spectroscopy. Here, a total of 33 spin–orbit (SO) states of PrO and 23 SO states of PrO + are predicted by second-order multiconfigurational quasi-degenerate perturbation (MCQDPT2) theory. Electronic transitions from four low-energy SO levels of the neutral molecule to the ground state of the singly charged cation are identified by combining the MATI spectroscopic measurements with the MCQDPT2 calculations. The precise ionization energy is used to reassess the ionization energies and the reaction enthalpies of the Pr + O → PrO + + e – chemi-ionization reaction reported in the literature. An empirical formula that uses atomic electronic parameters is proposed to predict the ionization energies of lanthanide monoxides, and the empirical calculations match well with available precise experimental measurements.

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

Ballistic Frenkel-exciton gate with a high on-off ratio

Here it is shown that the exciton interactions within organic dye aggregates, as modeled by the Frenkel Hamiltonian, enable the construction of an on/off switchable exciton gate. In this construction, a single exciton residing on a controlling gate molecule may pass or inhibit the ballistic propagation of an exciton in a proximal gate channel consisting of an array of dye molecules. High on-off ratios in excess of 102 can be achieved through the use of static difference dipole-dipole interactions between the gate and the gate channel which effectively creates a switchable Bragg grating. The gate channel and controlling gate molecule exhibit entanglement with the quantum mechanical superposition of the presence and absence of exciton occupation on the gate molecule.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2020

Materials Data on CO by Materials Project

CO is alpha carbon monoxide structured and crystallizes in the cubic P2_13 space group. The structure is zero-dimensional and consists of four formaldehyde molecules. C2+ is bonded in a single-bond geometry to one O2- atom. The C–O bond length is 1.14 Å. O2- is bonded in a single-bond geometry to one C2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Fe4C by Materials Project

Fe4C is Iron carbide structured and crystallizes in the cubic P-43m space group. The structure is zero-dimensional and consists of one carbanide;iron molecule. Fe is bonded in a single-bond geometry to one C atom. The Fe–C bond length is 1.79 Å. C is bonded in a tetrahedral geometry to four equivalent Fe atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on O2 by Materials Project

O2 is alpha oxygen-like structured and crystallizes in the monoclinic C2/m space group. The structure is zero-dimensional and consists of eight hydrogen peroxide molecules. O is bonded in a single-bond geometry to one O atom. The O–O bond length is 1.23 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on N2 by Materials Project

N2 is Cubic alpha N2 structured and crystallizes in the cubic P2_13 space group. The structure is zero-dimensional and consists of four 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 Cl2 by Materials Project

Cl2 is Cubic alpha N2-like structured and crystallizes in the orthorhombic Cmce space group. The structure is zero-dimensional and consists of four chlorine molecules. Cl is bonded in a single-bond geometry to one Cl atom. The Cl–Cl bond length is 2.01 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on H2O2 by Materials Project

H2O2 crystallizes in the tetragonal P4_12_12 space group. The structure is zero-dimensional and consists of eight water molecules. H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.01 Å. O is bonded in a single-bond geometry to one H atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on H2 by Materials Project

H2 is Cubic alpha N2-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is zero-dimensional and consists of two hydrogen molecules. H is bonded in a single-bond geometry to one H atom. The H–H bond length is 0.75 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on N2 by Materials Project

N2 is Cubic alpha N2 structured and crystallizes in the cubic Pa-3 space group. The structure is zero-dimensional and consists of four 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 CN by Materials Project

CN is alpha carbon monoxide-like structured and crystallizes in the orthorhombic Pbca space group. The structure is zero-dimensional and consists of eight hydrogen cyanide molecules. C3+ is bonded in a single-bond geometry to one N3- atom. The C–N bond length is 1.17 Å. N3- is bonded in a single-bond geometry to one C3+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ClF by Materials Project

ClF is alpha carbon monoxide-like structured and crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four chlorine fluoride molecules. Cl is bonded in a single-bond geometry to one F atom. The Cl–F bond length is 1.69 Å. F is bonded in a single-bond geometry to one Cl atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SiH by Materials Project

SiH is Cubane-like structured and crystallizes in the trigonal P-3m1 space group. The structure is zero-dimensional and consists of two silylidyne molecules. Si is bonded in a single-bond geometry to one H atom. The Si–H bond length is 1.50 Å. H is bonded in a single-bond geometry to one Si atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NO by Materials Project

NO is alpha carbon monoxide-like structured and crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four nitroxyl molecules. N is bonded in a single-bond geometry to one O atom. The N–O bond length is 1.17 Å. O is bonded in a single-bond geometry to one N atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HBr by Materials Project

HBr is alpha carbon monoxide structured and crystallizes in the orthorhombic P2_12_12_1 space group. The structure is zero-dimensional and consists of four hydrobromic acid molecules. H1+ is bonded in a single-bond geometry to one Br1- atom. The H–Br bond length is 1.44 Å. Br1- is bonded in a single-bond geometry to one H1+ atom.

36 MATERIALS SCIENCE↗