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At least 613 records · Page 34
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

High-Resolution Photoelectron Spectroscopy of NO3 – Vibrationally Excited Along Its ν3 Mode

The nitrate (NO3) radical has long been the subject of both experimental and theoretical studies due to its complex electronic structure resulting from vibronic interactions between its X̃2A2' and B̃2E' states. In particular, the definite assignment of the fundamental of its degenerate stretching vibration (ν3) is still under debate. Here, we report high-resolution photoelectron spectra of vibrationally pre-excited NO3- using the recently developed IR-cryo-SEVI technique. The anions are excited through infrared (IR) excitation near 1350 cm-1, accessing the ν3 and 2ν3(e') vibrational levels with band centers at 1350.5 and ∼2700 cm-1, respectively. The IR-cryo-SEVI spectrum for 2ν3 pre-excitation shows clear evidence for an intense 321 transition. From the position of this feature (30031 cm-1), the electron affinity of NO3 also determined in this work (31680 cm-1), and the IR excitation energy, we obtain a fundamental frequency of 1051 cm-1 for the ν3 fundamental of the NO3 radical. This assignment and other features in the IR-cryo-SEVI spectra are supported by spectral simulations based on a vibronic Köppel-Domcke-Cederbaum Hamiltonian. The simulations also show that nearly all features in the IR-cryo-SEVI spectra arise because of pseudo-Jahn-Teller coupling between the X̃ and B̃ states of NO3. The results and analysis presented here settle a long-standing controversy regarding the ν3 frequency of NO3.

Anions↗
DOE OSTI2025

The Electronic Structure of Zirconium and Hafnium Monochalcogenides

High-level ab initio CCSD(T) and spin–orbit icMRCI+Q calculations were used to predict potential energy curves (PECs) for the lowest-lying states of ZrO, ZrS, HfO, and HfS. The prediction of the ground state is basis set dependent at the icMRCI+Q level for ZrO and ZrS due to the small singlet–triplet splitting between the lowest 1 Σ + and 3 Δ states. CCSD(T) with a spin orbit correction predicted the 1 Σ + ground state in agreement with experiment. New all-electron basis sets were developed for Hf to improve the results over those predicted by use of effective core potentials (ECPs) that subsume the 4f electrons into the definition of the core. The use of the new DK-4f basis sets rather than ECPs became more important for HfO and HfS where there is a lack of a good core–valence separation. icMRCI+Q, CCSD(T), and DFT calculations for the spectroscopic parameters of ZrO, ZrS, HfO, and HfS were benchmarked with available experimental data. Bond dissociation energies (BDEs) of these four systems were calculated at the Feller–Peterson–Dixon (FPD) level to be 762.1 (ZrO), 543.5 (ZrS), 803.8 (HfO), and 575.1 kJ/mol (HfS), in excellent agreement with experiment. The HfS BDE was remeasured using the R3PI method, providing an updated experimental measurement of D 0 (HfS) = 5.978 ± 0.002 eV = 576.8 ± 0.2 kJ/mol. This experimental value, combined with experimental measurements of the ionization energies of Hf and HfS, gives the cationic BDE of D 0 (Hf + -S) = 5.124 ± 0.002 eV = 494.4 ± 0.2 kJ/mol.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Exploring Anomalous Photoelectron Angular Distributions in the Photoelectron Spectra of Gd 3 O 3 – : Study of Gd 3 O 2 – and Gd 3 O 3 – Using Photoelectron Spectroscopy and Density Functional Theory Calculations

Anion photoelectron (PE) spectra of lanthanide oxide clusters obtained previously have exhibited anomalous photoelectron angular distributions which were attributed to strong PE–valence electron (PEVE) interactions. Here, to further explore this effect, we have obtained the PE spectra of Gd 3 O 2 – and Gd 3 O 3 – , two clusters that have similarly complex electronic structures but contrasting symmetries. The spectra exhibit manifolds of detachment transitions at similar binding energies in a 0.5 eV window of energy. The electron affinity of Gd 3 O 2 is measured to be 1.29 ± 0.05 eV, and that of Gd 3 O 3 is 1.31 ± 0.05 eV. As seen in previous studies on lanthanide oxide cluster anions in lower than conventional oxidation states, transitions in spectra obtained lower photon energies are more congested than those obtained with higher photon energy, a signature of strong PEVE interactions. While the detachment transitions have predominantly parallel photoelectron angular distributions (PAD), the PAD varies across the manifold of transitions in the PE spectrum of Gd 3 O 3 – in a way that suggests four different subgroups of transitions. Results of calculations on Gd 3 O 2 – suggest kite or V-shape structures with antiferromagnetic coupling between one of the 4f 7 subshells with the two others. Calculations on Gd 3 O 3 – more definitively point to ring structures with a nearly isoenergetic ferromagnetically coupled high spin (24-tet) state and a dectet state in which one of the 4f 7 subshells is antiferromagnetically coupled with the other two. Taking these results as qualitative, we propose that strong mixing between the unperturbed states predicted computationally leads to overlapping transitions with different PADs.

anions↗
DOE OSTI2021

First-Principles Simulations of CuCl in High-Temperature Water Vapor

Experimental data suggest that the solubility of copper in high-temperature water vapor is controlled by the formation of hydrated clusters of the form CuCl(H 2 O) n , where the average number of water molecules in the cluster generally increases with increasing density [Migdisov, A. A.; et al. Geochim. Cosmochim. Acta2014, 129, 33–53]. However, the precise nature of these clusters is difficult to probe experimentally. Moreover, there are some discrepancies between experimental estimates of average cluster size and prior simulation work [Mei, Y. Geofluids2018, 2018, 4279124]. Here, we have performed first-principles Monte Carlo (MC) and molecular dynamics (MD) simulations to explore these clusters in finer detail. We find that molecular dynamics is not the most appropriate technique for studying aggregation in vapor phases, even at relatively high temperatures. Specifically, our MD simulations exhibit substantial problems in adequately sampling the equilibrium cluster size distribution. In contrast, MC simulations with specialized cluster moves are able to accurately sample the phase space of hydrogen-bonding vapors. At all densities, we find a stable, slightly distorted linear H 2 O–Cu–Cl structure, which is in agreement with the earlier simulations, surrounded by a variable number of water molecules. The surrounding water molecules do not form a well-defined second solvation shell but rather a loose network of hydrogen-bonded water with molecular CuCl on the outside edge of the water cluster. We also find a broad distribution of hydration numbers, especially at higher densities. In contrast to previous simulation work but in agreement with experimental data, we find that the average hydration number substantially increases with increasing density. Moreover, the value of the hydration number depends on the choice of cluster definition.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

First-Principles Study of Molecular Hydrogen Activation by Defects in Boron Nitride

Here, we used density functional theory simulations in combination with ab initio thermodynamics to determine the H 2 partial pressure (p H2 )-dependent energetics associated with H 2 activation and recovery at various defect sites in hexagonal boron nitride (h-BN). We found that some defects are very reactive with hydrogen, thereby definitely trapping hydrogen in defective h-BN. However, depending on hydrogen partial pressure, less reactive defect sites can be populated. Because of the lower binding capability of these sites, they would allow hydrogen to be recycled and recovered. For small defect sizes, we found that hydrogen preferentially binds to nitrogen sites by forming N–H bonds, and if no N sites are available then boron sites would be the next to bind hydrogen. Hydrogen dissociation via frustrated Lewis pair is found to be more favorable than forming only N–H bonds but only if the defect size is large enough to accommodate steric effects. For specific conditions such as T = 400 K, p H2 = 1 bar, and only considering one molecular H 2 per defect, three defects, namely, the N monovacancy, 3V(1B2N), and hexagonal 6V(3B3N) could play a role in both the activation and recycling of H 2 as they would be reacting enough to allow a favorable splitting of H 2 while not binding too strongly to allow its recovery. More broadly, a range of p H2 and hydrogen loading conditions were investigated for different types of defects and the finding suggests that p H2 could be used to fine-tune the Gibbs free energy of hydrogenation, thereby allowing several types of defects at different hydrogen loading contents to play a role in the activation/recovery process of H 2 in defective h-BN.

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

Extemporaneous Mechanochemistry: Shock-Wave-Induced Ultrafast Chemical Reactions Due to Intramolecular Strain Energy

We report regions of energy localization referred to as hotspots are known to govern shock initiation and the run-to-detonation in energetic materials. Mounting computational evidence points to accelerated chemistry in hotspots from large intramolecular strains induced via the interactions between the shock wave and microstructure. However, definite evidence mapping intramolecular strain to accelerated or altered chemical reactions has so far been elusive. From a large-scale reactive molecular dynamics simulation of the energetic material 1,3,5-triamino-2,4,6-trinitrobenzene, we map decomposition kinetics to molecular temperature and intramolecular strain energy prior to reaction. Both temperature and intramolecular strain are shown to accelerate chemical kinetics. A detailed analysis of the atomistic trajectory shows that intramolecular strain can induce a mechanochemical alteration of decomposition mechanisms. The results in this paper could inform continuum-level chemistry models to account for a wide range of mechanochemical effects.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Nonclassical Strong Metal–Support Interactions for Enhanced Catalysis

Strong metal–support interaction (SMSI), which encompasses reversible encapsulation and de-encapsulation and modulation of surface adsorption properties, imposes great impacts on the performance of heterogeneous catalysts. Recent development of SMSI has surpassed the prototypical encapsulated Pt-TiO 2 catalyst, affording a series of conceptually novel and practically advantageous catalytic systems. Here, in this work, we provide our perspective on recent progress in nonclassical SMSIs for enhanced catalysis. Unravelling the structural complexity of SMSI necessitates the combination of multiple characterization techniques at different scales. Synthesis strategies leveraging chemical, photonic, and mechanochemical driving forces further expand the definition and application scope of SMSI. Exquisite structure engineering permits elucidation of the interface, entropy, and size effect on the geometric and electronic characteristics. Materials innovation places the atomically thin two-dimensional materials at the forefront of interfacial active site control. A broader space is awaiting exploration, where exploitation of metal–support interactions brings compelling catalytic activity, selectivity, and stability.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Isolating the Vibrational Spectra of the Red Chlorophylls in Photosystem I with Multispectral Two-Dimensional Spectroscopy

Photosystem I (PSI) uses an antenna of chlorophyll (Chl) molecules to create a charge separated state with high quantum efficiency. Understanding the charge separation mechanism is currently hindered by spectral overlap between the antenna and reaction center (RC) Chls and the fact that energy transfer and electron transfer occur with similar time scales. Here, we characterize the antenna excited states by applying two-dimensional electronic (2DES) and two-dimensional electronic-vibrational (2DEV) spectroscopy to PSI complexes with closed RCs. Comparison of the 2DES and 2DEV spectra, which evolve with the same kinetics, enabled characterization of the vibrational modes of the antenna during energy equilibration between spectrally distinct Chls. Through global analysis, we learn how energy transfer between the Bulk and Red Chls presents in the 2DEV spectra and we definitively identify vibrations of the cationic components of the mixed exciton and intermolecular charge transfer states associated with the Red Chls. This work enables future studies of the initial charge separation mechanism of PSI by 2DEV spectroscopy.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

On the Thermodynamic Condition for Adsorption Azeotropes

Adsorption azeotropy is a common phenomenon in mixed-gas adsorption equilibria. Since the first literature report of binary adsorption azeotropes in 1933, numerous studies investigated the thermodynamic conditions for adsorption azeotropes but failed to reach definitive conclusions. Based on the generalized Langmuir isotherm model for multicomponent adsorption equilibria which takes into account the vacant site as part of the adsorbed phase, this study presents the thermodynamic condition for adsorption azeotropes as derived from the generalized Langmuir isotherm to be the equality of the ratios of adsorbed phase activity coefficient γi and adsorption equilibrium constant $K$$^{o}_{i}$ for the two adsorbates in the binary 1–2 adsorption system, i.e., γ 1 /$K$$^{o}_{1}$ = γ 2 /$K$$^{o}_{2}$. This adsorption azeotropic condition is analogous to the vapor–liquid equilibrium azeotropic condition, i.e., the equality of the products of liquid phase activity coefficient and saturation vapor pressure Pisat for the two components, i.e., γ 1 $P$$^{sat}_{1}$ = γ 2 $P$$^{sat}_{2}$. We validated the thermodynamic condition for adsorption azeotropes with 14 azeotrope-forming adsorption systems in this study. As a result, we investigated the effects of the pressure, temperature, and adsorbed phase nonideality on azeotrope formation.

42 ENGINEERING↗
DOE OSTI2024

Physical and Chemical Responses of Amidine-Containing Polymers in the Capture and Release of CO 2

Polymeric materials containing amidine motifs are of high interest due to their ability to reversibly capture and release CO 2 at ambient temperature. Here, in this study, we probe physical and chemical responses of styrene-based copolymers containing linear amidine motifs as functions of CO 2 and inert gas exposures and temperature. A copper-catalyzed azide–alkyne cycloaddition “click” reaction involving N′-propargyl-N,N-dimethylacetamidine is used to modify random copolymers, resulting in an array of linear amidine motifs along the chain backbone with the amount of CO 2 -active amidine controlled by the copolymer composition. Through thermogravimetric measurements, we demonstrate that the amidine-functionalized copolymers efficiently capture CO 2 upon exposure to a stream of CO 2 (at 27 °C) and release it at a slightly elevated temperature (50 °C) when exposed to an inert gas stream (N 2 ). In addition to displaying a maximum adsorption capacity of 22 wt % in the presence of pure CO 2 , the copolymers show composition-dependent direct air capture (DAC) behaviors. Small molecule analogs are used to definitively understand degradation via chemical hydrolysis of the amidine moiety, which leads to insolubility and a large reduction in CO 2 adsorption capacity (1.7 wt %). Neutron vibrational spectroscopy and DFT calculations confirm that CO 2 binds strongly to the amidine motif, inducing a strong bending of the CO 2 molecule from its linear geometry. The coupled insights into mechanisms and behaviors of CO 2 adsorption in amidine-functionalized polymers provides a foundation for future investigations of CO 2 -responsive polymers and soft materials to improve carbon capture and sequestration technologies.

Chun, Danielle J.↗
DOE OSTI2021

Valence Effects of Fe Impurity for Recovered LiNi 0.6 Co 0.2 Mn 0.2 O 2 Cathode Materials

Iron impurities are generally included in the obtained leaching liquor solution during the hydrometallurgical recycling method of spent lithium-ion batteries (LIBs) due to the usage of iron in battery casings and machinery parts of recycling equipment, which would definitely affect the physical and electrochemical features of the recovered active materials. In this paper, the effects of iron impurity with different valence states (Fe 2+ and Fe 3+ ) and gradient concentrations (0.2, 1.0, and 5.0 at. %) for the obtained LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM622) cathodes are fully studied. It is found that Fe3+ impurity could easily lower the tap density and average size of NCM622 particles and even introduce some impurity phases in the NCM622 structure at high concentration (5.0 at. %), leading to much lower specific capacity, worse rate capability, and cycling performance of the Fe 3+ -based NCM622 cathode. On contrast, with certain concentrations of Fe 2+ impurity (0.2 and 1.0 at. %), the NCM622 cathode material exhibits comparable and much better electrochemical properties compared with the virgin NCM622 materials. Based on these results, the valence of Fe impurity should be considered and controlled as well as its concentration during the recycling process design for spent LIBs.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Adhesive Polymers as Efficient Binders for High-Capacity Silicon Electrodes

The major cause for capacity fading of silicon nanoparticle (SiNP)-based electrodes is the immense pressure applied toward the conductive networks during the charge/discharge process. While numerous efforts have been devoted to investigating different types of polymer binders, the rational design of an adhesive binder with pressure sensitivity has rarely been reported. Herein, a series of pressure-sensitive adhesives (PSAs) synthesized via copolymerization of 2-ethylhexyl acrylate (2-EHA) and acrylic acid (AA) are evaluated as polymer binders for SiNP-based electrodes. The balance between the density of interaction groups and viscoelastic properties is systematically investigated for efficient binding performance. The SiNP-based electrode using PSA with 20 mol % of 2-EHA (Si-PSA-20%) exhibits excellent electrochemical performance, achieving a capacity retention of 83% at the 100th cycle compared with 54% for Si-PAA after activation. Si-PSA-20% also delivers a superior cycling performance at a high current density (1731 mAh g –1 after 350 cycles vs 719 mAh g –1 after 150 cycles for Si-PAA, 1.8 A g –1 ) and at high mass loading of active materials (capacity retention of 74 vs 38% for Si-PAA after 100 cycles, SiNP content ~1.2 mg cm –2 ). Atomic force microscopy (AFM), peel tests, and Car–Parrinello molecular dynamics (CPMD) simulations are employed to understand their binder performance. The novel design and systematical investigation of PSAs as binders will definitely be appealing for not only the Si electrode but also for other high-energy-density electrode materials.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Back-Surface Passivation of CdTe Solar Cells Using Solution-Processed Oxidized Aluminum

Although back-surface passivation plays an important role in high-efficiency photovoltaics, it has not yet been definitively demonstrated for CdTe. Here, we present a solution-based process, which achieves passivation and improved electrical performance when very small amounts of oxidized Al 3+ species are deposited at the back surface of CdTe devices. The open circuit voltage (V oc ) is increased and the fill factor (FF) and photoconversion efficiency (PCE) are optimized when the total amount added corresponds to ~1 monolayer, suggesting that the passivation is surface specific. Addition of further Al 3+ species, present in a sparse alumina-like layer, causes the FF and PCE to drop as the interface layer becomes blocking to current flow. The optimized deposit increases the average baseline PCE for both Cu-free devices and devices where Cu is present as a dopant. The greatest improvement is found when the Al 3+ species are deposited prior to the CdCl 2 activation step and Cu is employed. In this case, the best-cell efficiency was improved from 12.6 to 14.4%. Furthermore, time-resolved photoluminescence measurements at the back surface and quantum efficiency measurements performed at the maximum power point indicate that the performance enhancement is due to a reduction in the interface recombination current at the back surface.

14 SOLAR ENERGY↗
DOE OSTI2021

Patternable Mesoporous Thin Film Quantum Materials via Block Copolymer Self-Assembly: An Emergent Technology?

Recent developments in quantum materials hold promise for revolutionizing energy and information technologies. The use of soft matter self-assembly, for example, by employing block copolymers (BCPs) as structure directing or templating agents, offers facile pathways toward quantum metamaterials with highly tunable mesostructures via scalable solution processing. Here, we report the preparation of patternable mesoporous niobium carbonitride-type thin film superconductors through spin-coating of a hybrid solution containing an amphiphilic BCP swollen by niobia sol precursors and subsequent thermal processing in combination with photolithography. Spin-coated as-made BCP-niobia hybrid thin films on silicon substrates after optional photolithographic definition are heated in air to produce a porous oxide, and subsequently converted in a multistep process to carbonitrides via treatment with high temperatures in reactive gases including ammonia. Grazing incidence small-angle X-ray scattering suggests the presence of ordered mesostructures in as-made BCP-niobia films without further annealing, consistent with a distorted alternating gyroid morphology that is retained upon thermal treatments. Wide-angle X-ray scattering confirms the synthesis of phase-pure niobium carbonitride nanocrystals with rock-salt lattices within the mesoscale networks. Electrical transport measurements of unpatterned thin films show initial exponential rise in resistivity characteristic of thermal activation in granular systems down to 12.8 K, at which point resistivity drops to zero into a superconducting state. Magnetoresistance measurements determine the superconducting upper critical field to be over 16 T, demonstrating material quality on par with niobium carbonitrides obtained from traditional solid-state synthesis methods. Here. we discuss how such cost-effective and scalable solution-based quantum materials fabrication approaches may be integrated into existing microelectronics processing, promising the emergence of a technology with tremendous academic and industrial potential by combining the capabilities of soft matter self-assembly with quantum materials.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Degrees of Rate Control at Non(pseudo)steady-State Conditions

The degrees of rate control enable identification of rate-controlling transition states and species during (pseudo-)steady-state reaction. We demonstrate a method for identifying rate-controlling transition states and species at non-(pseudo-)steady-state conditions through modification of the definitions for degrees of rate control and sensitivities by superimposing the condition that time constants of the analytical rate function are kept constant when taking the partial derivatives of rate with respect to the rate constants/free energies. In conclusion, the utility of transient degrees of rate control is demonstrated for catalytic reaction networks to rationalize features of the transient rate including extrema and discontinuities.

42 ENGINEERING↗
DOE OSTI2023

Energy Flows in Static and Programmable Catalysts

Programmable catalysts that change on the time scale of a catalytic cycle provide a new opportunity to control the flow of energy to reactants and products to promote faster and more selective chemistry. While traditional chemical manufacturing processes consume energy to achieve favorable reaction conditions, programmable catalysts aim to dynamically add or remove energy to catalytic cycles through perturbations of the catalytic surface via strain, charge, or light. These surface energy flows are quantified by the changes in adsorbate binding energy with time, and the overall efficiency relating energy inputs to catalytic performance is defined by the characteristics of the undulating catalytic surface. Here, understanding and quantifying energy flows in programmable catalysts provides baseline definitions and metrics for comparing dynamic conditions and identifying optimal catalytic performance for more efficient chemical manufacturing.

Binding energy↗
DOE OSTI2024

Benchmarking Guanidinium Organosulfonate Hydrogen-Bonded Frameworks for Structure Determination of Encapsulated Guests

Single crystal X-ray diffraction (SCXRD) is arguably the most definitive method for molecular structure determination, but it is often challenged by compounds that are liquids or oils at room temperature or do not form crystals adequate for analysis. Our laboratory previously reported a simple, cost-effective, single-step crystallization method based on guanidinium organosulfonate (GS) hydrogen bonded frameworks for structure determination of a wide range of encapsulated guest molecules, including assignment of the absolute configuration of chiral centers. Herein, we expand on those results and report a head-to-head comparison of the GS method with adamantoid “molecular chaperones”, which have been reported to be useful hosts for structure determination. Inclusion compounds limited to only two GS hosts are characterized by low R1 values and Flack parameters, infrequent disorder of the host and guest, and manageable disorder when it does exist. The structures of some target molecules that were not included or resolved using the adamantoid chaperones were successfully included and resolved by the GS hosts, and vice versa. Of the 32 guests attempted by the GS method, 31 inclusion compounds afforded successful guest structure solutions, a 97% success rate. The GS hosts and adamantoid chaperones are complementary with respect to guest inclusion, arguing that both should be employed in the arsenal of methods for structure determination. Furthermore, the low cost of organosulfonate host components promises an accessible route to molecular structure determination for a wide range of users.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Lignin Monomers from beyond the Canonical Monolignol Biosynthetic Pathway: Another Brick in the Wall

Lignin is conventionally defined as being formed by the oxidative polymerization of three main monolignols, p-coumaryl alcohol, coniferyl alcohol, and sinapyl alcohol, that are derived from the general phenylpropanoid biosynthetic pathway. Many other phenolic compounds that are also derived from the phenylpropanoid pathway are also known to perform as genuine lignin monomers in many plants, as is the case of the monolignol ester conjugates, phenolic compounds arising from the truncated biosynthesis of monolignols, or ferulate esters. Recent investigations, however, have indicated that phenolic compounds arising from beyond the canonical phenylpropanoid pathway, namely flavonoids, hydroxystilbenes, and hydroxycinnamic amides, may also behave as authentic lignin monomers and are incorporated into the lignin in some plants, further challenging the traditional definition of lignin. This is the case of the flavone tricin that is incorporated into the lignin of grasses and other monocots, the hydroxystilbene piceatannol (together with resveratrol and isorhapontigenin, at lower levels) that has been found in the lignins of palm fruit shells, their respective O-glucosides (astringin, piceid, and isorhapontin) that are present in the lignin of Norway spruce bark, or the ferulic amides feruloyltyramine, incorporated into the lignin of tobacco and potato tubers, and diferuloylputrescine, which appears to be incorporated into maize kernel lignin. These valuable compounds are potentially available in high amounts and at low cost and may be obtained from the waste products from the processing of agricultural or forest biomass.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗