Removing organic ligands from colloidal nanoparticles is critical for fabricating solid-state devices, yet accurately quantifying this removal remains a significant analytical challenge. Here, we establish a robust and accessible method for this quantification by calibrating Raman spectroscopy against precise ion beam analysis (IBA) for nanoparticle assemblies (CNAs) processed by helium (He) and oxygen (O2) plasmas. We demonstrate that the calibration curves are remarkably independent of plasma power and pressure, depending critically only on the choice of feed gas. He plasma induces rapid dehydrogenation and cross-linking, evidenced by a much faster decrease in the C-H Raman signal relative to the actual carbon loss. Conversely, O2 plasma leads to a surprising "apparent hydrogenation", where the carbon backbone is removed significantly faster than the C-H signal diminishes. This counterintuitive effect is explained by a serial mechanism of oxidative fragmentation; β-scission cleaves the alkyl chains, and subsequent stabilization steps enrich the remaining film with hydrogen-rich methyl-terminated fragments, while carbon is efficiently removed as volatile CO. This work provides calibrated functions that enable the rapid determination of absolute carbon content in processed CNAs using simple Raman spectroscopy with uncertainties of ∼8% for O2 and ∼12% for He plasma, offering a vital tool for both process diagnostics and fundamental studies of plasma-matter interactions in colloidal nanocrystal films.

An international collaboration was established as a Coordinated Research Project (CRP) under the IAEA and entitled Accelerator Simulation and Theoretical Modelling of Radiation Effects-II (SMoRE-II). It was created to determine, by way of a Round Robin process, the degree to which ion irradiations produced the same irradiated microstructure when conducted in different labs on the same alloy and provided with the same irradiation protocol. The Round Robin consisted of 13 participating organizations from 9 IAEA member states with ion irradiations conducted at all CRP partner sites on samples of a single alloy (T91) from a single billet with the same thermal-mechanical history, and with a specific protocol for conducting the irradiations. Of the 14 parameters specified for the ion irradiations, only 1 of 12 facilities was able to follow the protocol exactly. Major differences included vacuum pressure, temperature measurement and control, beam mode (raster-scanning vs. steady beam), and dosimetry. The microstructure features characterized were the sizes and number densities of cavities, dislocation loops, precipitates, and the radiation induced segregation. While loop size and number density appeared to correlate with carbon content, no such correlation was identified for cavities. The divergence from the irradiation protocol undoubtedly affected the irradiated microstructure with carbon contamination occurring in most cases. The cavity, dislocation loop and precipitate microstructures all fell within the range of that in the literature. Additionally, a T91 sample that was irradiated to 47 dpa at 376 degrees C in the BOR-60 reactor was selected for comparison of the microstructure to those in the Round Robin study.

High moderation per unit volume solid moderator materials like yttrium hydride (YHx) are necessary for compact nuclear microreactors. However, the phase stability and hydrogen transport processes of YHx under hightemperature irradiation are largely unknown. Proton irradiation was conducted on YHx at 300 degrees C and 580 degrees C to 0.2 dpa using 1 MeV or 2 MeV protons in a high-vacuum environment. The hydrogen concentration was determined before and after irradiation using elastic recoil detection analysis, and microstructural evolution was examined via post-irradiation scanning transmission electron microscopy and Raman spectroscopy. Dislocation loops and cavities were observed in all conditions; their distribution was correlated with the bombarding proton energy and ion irradiation temperature. This work revealed that hydrogen retention is proportional to the formation of traps for hydrogen gas atoms and identified pathways for hydrogen release. The relative contributions of bulk or fast diffusion paths, such as grain boundaries, delamination boundaries, and stacking faults are discussed; the primary mechanisms of hydrogen loss are likely based on diffusion, ruling out artefacts of the experimental design. The study suggests proton irradiation may be a strong surrogate to study hydrogen transport in hydride moderator materials under irradiation.

We present a new set of reference materials, the ND70‐series, for in situ measurement of volatile elements (H2O, CO2, S, Cl, F) in silicate glass of basaltic composition. The materials were synthesised in piston cylinders at pressures of 1 to 1.5 GPa under volatile‐undersaturated conditions. They span mass fractions from 0 to 6% m/m H2O, from 0 to 1.6% m/m CO2 and from 0 to 1% m/m S, Cl and F. The materials were characterised by elastic recoil detection analysis for H2O, by nuclear reaction analysis for CO2, by elemental analyser for CO2, by Fourier transform infrared spectroscopy for H2O and CO2, by secondary ion mass spectrometry for H2O, CO2, S, Cl and F, and by electron probe microanalysis for CO2, S, Cl and major elements. Comparison between expected and measured volatile amounts across techniques and institutions is excellent. It was found however that SIMS measurements of CO2 mass fractions using either Cs+ or O− primary beams are strongly affected by the glass H2O content. Reference materials have been made available to users at ion probe facilities in the US, Europe and Japan. Remaining reference materials are preserved at the Smithsonian National Museum of Natural History where they are freely available on loan to any researcher.

GeSnC alloys offer a route to direct bandgap semiconductors for CMOS-compatible lasers, but the use of CBr4 as a carbon source was shown to reduce Sn incorporation by 83%–92%. We report on the role of thermally cracked H in increasing Sn incorporation by 6x–9.5x, restoring up to 71% of the lost Sn, and attribute this increase to removal of Br from the growth surface as HBr prior to formation of volatile groups such as SnBr4. Furthermore, as the H flux is increased, Rutherford backscattering spectroscopy reveals a monotonic increase in both Sn and carbon incorporation. X-ray diffraction reveals tensile-strained films that are pseudomorphic with the substrate. Raman spectroscopy suggests substitutional C incorporation; both x-ray photoelectron spectroscopy and Raman suggest a lack of graphitic carbon or its other phases. For the lowest growth temperatures, scanning transmission electron microscopy reveals nanovoids that may account for the low Sn substitutional fraction in those layers. Conversely, the sample grown at high temperatures displayed abrupt interfaces, notably devoid of any voids, tin, or carbon-rich clusters. Finally, the surface roughness decreases with increasing growth temperature. These results show that atomic hydrogen provides a highly promising route to increase both Sn and C to achieve a strongly direct bandgap for optical gain and active silicon photonics.

We present a new approach to determine in situ CO 2 and H 2 O concentrations in apatite via attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). Absolute carbon and hydrogen measurements by nuclear reaction analysis (NRA) and elastic recoil detection (ERD) are used to calibrate ATR-FTIR spectra of CO 2 and H 2 O in apatite. We show that CO 2 and H 2 O contents in apatite can be determined via linear equations ( r 2 > 0.99) using the integrated area of CO 2 and H 2 O IR absorption bands. The main benefits of this new approach are that ATR-FTIR analyses are non-destructive and can be conducted on polished sample material surfaces with a spatial resolution of ~ 35 μm. Furthermore, the wavenumber of the phosphate IR absorption band can be used to determine the crystallographic orientation of apatite, which allows for accurate quantification of CO 2 and H 2 O in randomly orientated apatite grains. The limit of quantification of H 2 O in apatite is ~ 400 ppm and ~ 100 ppm for CO 2 . Via two examples, one from a carbonatite and one from a metasedimentary rock, we show that this new technique opens up new possibilities for determining volatile concentrations and behavior in a wide range of hydrothermal, igneous, and metamorphic systems.

A method was developed to quantify the spatial distribution and implantation depth of energy-degraded light ions with a thin foil rotating energy degrader for use during multiple ion beam irradiation. The methodology covers three physical phenomena: ions passing through the thin foil, ions travelling through the vacuum to the target, and ion implantation into the target, and accounts for the distribution of ions both in depth and in plane. The processes of energy straggling and scattering were calculated using SRIM. The effects of raster-scanning, and the geometry of the system were implemented in scripts handling the SRIM output files. Elastic backscattering (EBS) using 2.38 MeV H+ protons was used to measure the helium depth profiles after implantation with and without thin foil energy degradation. Defect analysis with transmission electron microscopy confirmed the implantation profiles measured with EBS and calculated with SRIM.

This paper describes the creation of mesoporous inorganic films based on the plasma processing of ligand-capped nanocrystals. We use nanorods of HfO2 as a model system and report an extensive characterization of the chemistry, structure, mechanical properties, and reactivity to show that (i) the aspect ratio of the nanorods regulates the pore size and pore volume of the films in a predictable manner and yields an increase in porosity over spherical nanocrystals of up to 60%, (ii) the modulus (>25 GPa) and hardness (>1.1 GPa) are sufficient to tolerate chemical-mechanical planarization, and (iii) the catalytic activity can be finely controlled by the choice of ligands, which regulate the surface chemistry and water adsorption in the final product. This approach is an attractive route to create in two simple and scalable steps crack-free inorganic mesoporous films for applications in catalysis, energy storage, energy harvesting, and more.

This paper describes the kinetic limitations of etching ligands from colloidal nanocrystal assemblies (CNAs) by plasma processing. We measured the etching kinetics of ligands from a CNA model system (spherical ZrO2 nanocrystals, 2.5-3.5 nm diameter, capped with trioctylphosphine oxide) with inductively coupled plasmas (He and O-2 feed gases, powers ranging from 7 to 30 W, at pressures ranging from 100 to 2000 mTorr and exposure times ranging between 6 and 168 h). The etching rate slows down by about one order of magnitude in the first minutes of etching, after which the rate of carbon removal becomes proportional to the third power of the carbon concentration in the CNA. Pressure oscillations in the plasma chamber significantly accelerate the overall rate of etching. These results indicate that the rate of etching is mostly affected by two main factors: (i) the crosslinking of the ligands in the first stage of plasma exposure, and (ii) the formation of a boundary layer at the surface of the CNA. Optimized conditions of plasma processing allow for a 60-fold improvement in etching rates compared to the previous state of the art and make the timeframes of plasma processing comparable to those of calcination.

Helium plasmas are attractive reagents for the removal of organics from hybrid materials because of their minimal ablative power and relative inertness, compared to oxidizing feed gases such as O2 and highly ablative inert gases such as Ar. This work describes the use of dilute helium plasmas to selectively remove the organic ligands from films of colloidal nanoparticles (i.e., colloidal nanoparticle assemblies). We determine the relative contribution to etching of different plasma species in a model system consisting of films of ZrO2 nanoparticles capped with trioctylphosphine oxide. Unexpectedly, we find that the strong ultraviolet radiation of He plasma is only a minor contributor to etching (25% of the etched carbon). Excited He species are responsible for most of the etching (75% of the etched carbon). Carbon concentrations as low as 3.5 atom % can be achieved under non-optimized plasma processing conditions.

The effects of transmutation produced helium and hydrogen must be included in ion irradiation experiments to emulate the microstructure of reactor irradiated materials. Descriptions of the criteria and systems necessary for multiple ion beam irradiation are presented and validated experimentally. A calculation methodology was developed to quantify the spatial distribution, implantation depth and amount of energy-degraded and implanted light ions when using a thin foil rotating energy degrader during multi-ion beam irradiation. A dual ion implantation using 1.34 MeV Fe+ ions and energy-degraded D+ ions was conducted on single crystal silicon to benchmark the dosimetry used for multi-ion beam irradiations. Secondary Ion Mass Spectroscopy (SIMS) analysis showed good agreement with calculations of the peak implantation depth and the total amount of iron and deuterium implanted. The results establish the capability to quantify the ion fluence from both heavy ion beams and energy-degraded light ion beams for the purpose of using multi-ion beam irradiations to emulate reactor irradiated microstructures.

We here describe a bottom-up approach to control the composition of solid/solid interfaces in nanostructured materials, and we test its effectiveness on tetragonal ZrO2, an inorganic phase of great technological significance. Colloidal nanocrystals capped with trioctylphosphine oxide (TOPO) or oleic acid (OA) are deposited, and the organic fraction of the ligands is selectively etched with O-2 plasma. The interfaces in the resulting all-inorganic colloidal nanocrystal assemblies are either nearly bare (for OA-capped nanocrystals) or terminated with phosphate groups (for TOPO-capped nanocrystals) resulting from the reaction of phosphine oxide groups with plasma species. The chemical modification of the interfaces has extensive effects on the thermodynamics and kinetics of the material. Different growth kinetics indicate different rate limiting processes of growth (surface diffusion for the phosphate-terminated surfaces and dissolution for the "bare" surfaces). Phosphate termination led to a higher activation energy of growth, and a 3-fold reduction in interfacial energy, and facilitated significantly the conversion of the tetragonal phase into the monoclinic phase. Films devoid of residual ligands persisted in the tetragonal phase at temperatures as high as 900 degrees C for 24 h.

Removing organics from hybrid nanostructures is a crucial step in many bottom-up materials fabrication approaches. It is usually assumed that calcination is an effective solution to this problem, especially for thin films. This assumption has led to its application in thousands of papers. We here show that this general assumption is incorrect by using a relevant and highly controlled model system consisting of thin films of ligand-capped ZrO 2 nanocrystals. After calcination at 800 °C for 12 h, while Raman spectroscopy fails to detect the ligands after calcination, elastic backscattering spectrometry characterization demonstrates that ~18% of the original carbon atoms are still present in the film. By comparison plasma processing successfully removes the ligands. Our growth kinetic analysis shows that the calcined materials have significantly different interfacial properties than the plasma-processed counterparts. Calcination is not a reliable strategy for the production of single-phase all-inorganic materials from colloidal nanoparticles.

Specimens of polymethylmethacrylate (PMMA) were implanted with 400-keV Ag+ ions at different ion fluences ranging from 1×1014 to 5×1015ions/cm2 using a 400-kV NEC ion implanter. The surface topographical features of the implanted PMMA were investigated by a confocal microscope. Modifications in the structural properties of the implanted specimens were analyzed in comparison with pristine PMMA by X-ray diffraction (XRD) and Raman spectroscopy. UV–Visible spectroscopy was applied to determine the effects of ion implantation on optical transmittance of the implanted PMMA. The confocal microscopic images revealed the formation of hillock-like microstructures along the ion track on the implanted PMMA surface. The increase in ion fluence led to more nucleation of hillocks. The XRD pattern confirmed the amorphous nature of pristine and implanted PMMA, while the Raman studies justified the transformation of Ag+-implanted PMMA into amorphous carbon at the ion fluence of ⩾5×1014ions/cm2. Moreover, the decrease in optical transmittance of PMMA is associated with the formation of hillocks and ion-induced structural modifications after implantation.

We have calibrated the infrared (IR) method for determining CO2 concentrations in apatite with absolute concentrations obtained through nuclear reaction analysis (NRA). IR data were obtained on double-polished apatite wafers using polarized transmission IR spectroscopy. Due to the various sites and orientations of CO32- in apatite, the IR spectra are complicated and do not have the same shape in different apatite samples. Hence, simple peak heights are not used to characterize CO2 concentrations in apatite. The total absorbance (A(total)) was derived using the integrated area under the curves in a given polarized spectral region. Then A(total) is calculated as A(E//c) + 2A(E perpendicular to c). The calibration has been carried out for two wavenumber regions, one with high sensitivity and the other applicable to apatite with high CO2 concentrations. The first calibration is for the fundamental asymmetric CO32- stretching at wavenumbers of 1600-1300 cm(-1), and the CO2 concentration in parts per million can be obtained as (0.0756 +/- 0.0036) A(total)/d where d is sample thickness in centimeters. The fundamental stretching bands are strong and hence sensitive for measuring low CO2 concentrations in apatite, down to parts per million level. The second calibration is for the CO32- bands at wavenumbers of 2650-2350 cm(-1), and the CO2 concentration in parts per million is (9.3 +/- 0.6) A(total)/d where d is sample thickness in centimeters. These bands are weak and hence are useful for measuring high CO2 concentrations in apatite without preparation of super-thin wafers. The anisotropy is significant. The difference between A(E//c) and A(E perpendicular to c) can reach a factor of 2.73. Hence, for high accuracy, it is best to use polarized IR to determine CO2 concentrations in apatite. For rough estimation, unpolarized IR spectra may be used by estimating A(total) = 3A(unpol), where A(unpol) is the integrated absorbance from unpolarized spectra.

Ion implantation is a versatile technique to tailor the surface properties of polymers in a controlled manner. In the present study, samples of poly (methyl methacrylate) (PMMA) have been implanted with 400keV silver (Ag+) ion beam to various ion fluences ranging from 5×1013 to 5×1015ions/cm2. The effect of Ag+ ion-induced disorder on morphological, chemical and optical properties of PMMA is analyzed using Atomic Force Microscope (AFM), Fourier transform infrared spectroscopy (FTIR) and ultraviolet–visible (UV–Vis) spectroscopy. Furthermore, the electrical conductivity of pristine and implanted PMMA is measured using four probe apparatus. The AFM images revealed the growth of nano-sized grainy structures and hillocks above the surface of implanted PMMA. The FTIR spectra confirmed the modifications in chemical structure of PMMA along with the formation of CC carbon contents. The refractive index, extinction coefficient and photoconductivity of implanted PMMA have been found to increase as a function of ion fluence. Simultaneously, indirect optical band gap is reduced from 3.13 to 0.81eV at a relatively high fluence (5×1015ions/cm2). A linear correlation has been established between the band gap and Urbach energies. Moreover, the electrical conductivity of Ag+ implanted PMMA has increased from 2.14×10−10 (pristine) to 9.6×10−6S/cm.

Specimens of polymethylmethacrylate (PMMA) have been implanted with 400 keV Cr+ ions at different ion fluences ranging from 5 × 1013 to 5 × 1015 ions/cm2. The possible chemical reactions involved in the nucleation of conjugated carbonaceous clusters in implanted PMMA are discussed. Furthermore, impact of formation of carbonaceous clusters on structural, optical, electrical and morphological properties of implanted PMMA has been examined. The structural modifications in implanted PMMA are observed by Raman spectroscopy. The variation in optical band gap and Urbach energy is measured using UV–visible spectroscopic analysis. The effects of Cr+ ion implantation on electrical and morphological properties are investigated by four-probe apparatus and atomic force microscopy, respectively. The Raman spectroscopic analysis confirmed the formation of carbonaceous clusters with the transformation of implanted layer of PMMA into amorphous carbon. Simultaneously, the optical band gap of implanted PMMA has reduced from 3.13 to 0.85 eV. The increase in Urbach energy favors the decline in band gap together with the structural modification in implanted PMMA. As a result of Cr+ ion implantation, the electrical conductivity of PMMA has improved from 2.14 ± 0.06 × 10−10 S/cm (pristine) to 7.20 ± 0.36 × 10−6 S/cm. The AFM images revealed a decrease in surface roughness with an increment in ion fluence up to 5 × 1014 ions/cm2. The modification in the electrical, optical and structural properties makes the PMMA a promising candidate for its future utilization, as a semiconducting and optically active material, in various fields like plastic electronics and optoelectronic devices.

Abstract Ion implantation has a potential to modify the surface properties and to produce thin conductive layers in insulating polymers. For this purpose, poly-allyl-diglycol-carbonate (CR-39) was implanted by 400 keV Au+ ions with ion fluences ranging from 5 × 1013 ions/cm2 to 5 × 1015 ions/cm2. The chemical, morphological and optical properties of implanted CR-39 were analyzed using Raman, Fourier transform infrared (FT-IR) spectroscopy, atomic force microscopy (AFM) and UV-Vis spectroscopy. The electrical conductivity of implanted samples was determined through four-point probe technique. Raman spectroscopy revealed the formation of carbonaceous structures in the implanted layer of CR-39. From FT-IR spectroscopy analysis, changes in functional groups of CR-39 after ion implantation were observed. AFM studies revealed that morphology and surface roughness of implanted samples depend on the fluence of Au ions. The optical band gap of implanted samples decreased from 3.15 eV (for pristine) to 1.05 eV (for sample implanted at 5 × 1015 ions/cm2). The electrical conductivity was observed to increase with the ion fluence. It is suggested that due to an increase in ion fluence, the carbonaceous structures formed in the implanted region are responsible for the increase in electrical conductivity.