Characterization of a distributed plasma ionization source (DPIS) for ion mobility spectrometry and mass spectrometry

A recently developed atmospheric pressure ionization source, a distributed plasma ionization source (DPIS), was characterized and compared to commonly used atmospheric pressure ionization sources with both mass spectrometry (MS) and ion mobility spectrometry (IMS). The source consisted of two electrodes of different sizes separated by a thin dielectric. Application of a high RF voltage across the electrodes generated plasma in air yielding both positive and negative ions. These reactant ions subsequently ionized the analyte vapors. The reactant ions generated were similar to those created in a conventional point-to-plane corona discharge ion source. The positive reactant ions generated by the source were mass identified as being solvated protons of general formula (H₂O)_nH⁺ with (H₂O)₂H⁺ as the most abundant reactant ion. The negative reactant ions produced were mass identified primarily as CO₃⁻, NO₃⁻, NO₂⁻, O₃⁻ and O₂⁻ of various relative intensities. The predominant ion and relative ion ratios varied depending upon source construction and supporting gas flow rates. A few compounds including drugs, explosives and amines were selected to evaluate the new ionization source. The source was operated continuously for 3 months and although surface deterioration was observed visually, the source continued to produce ions at a rate similar that of the initial conditions.     

Transport Coefficients in Water Plasma: Part I: Equilibrium Plasma

Knowledge of the transport coefficients of steam water plasma is important for modeling plasma flow processes and heat transfer. In this study, calculations of these properties were performed in a temperature range from 400 to 30,000 K and at pressures of 0.5, 1.0, 5.0 and 10 bar. Herein the composition of water plasma was determined at equilibrium. First, the most recent data on potential interactions and elastic differential cross sections for interacting particles were carefully examined in order to choose those most appropriate for determining the collision integrals. Second, we restricted the number of species to ten (e, H, O, H⁺, O⁺, O⁺⁺, H₂, O₂, OH and H₂O) and tested our collision integrals by comparing the thermal conductivity and viscosity to experimental data for water (at low temperatures). Finally, the total thermal conductivity, viscosity and electrical conductivity were calculated for different pressures.     

Mass spectrometric monitoring of oxidation of aliphatic C6–C8 hydrocarbons and ethanol in low pressure oxygen and air plasmas

Experimental and theoretical studies on the oxidation of saturated hydrocarbons (n‐hexane, cyclohexane, n‐heptane, n‐octane and isooctane) and ethanol in 28 Torr O₂ or air plasma generated by a hollow cathode discharge ion source were made. Ions corresponding to [M + 15]⁺ and [M + 13]⁺ in addition to [M ? H]⁺ and [M ? 3H]⁺ were detected as major ions where M is the sample molecule. The ions [M + 15]⁺ and [M + 13]⁺ were assigned as oxidation products, [M ? H + O]⁺ and [M ? 3H + O]⁺, respectively. By the tandem mass spectrometry analysis of [M ? H + O]⁺ and [M ? 3H + O]⁺, H₂O, olefins (and/or cycloalkanes) and oxygen‐containing compounds were eliminated from these ions. Ozone as one of the terminal products in the O₂ plasma was postulated as the oxidizing reagent. As an example, the reactions of C₆H₁₄^+? with O₂ and of C₆H₁₃⁺ (CH₃CH₂CH⁺CH₂CH₂CH₃) with ozone were examined by density functional theory calculations. Nucleophilic interaction of ozone with C₆H₁₃⁺ leads to the formation of protonated ketone, CH₃CH₂C(=OH⁺)CH₂CH₂CH₃. In air plasma, [M ? H + O]⁺ became predominant over carbocations, [M ? H]⁺ and [M ? 3H]⁺. For ethanol, the protonated acetic acid CH₃C(OH)₂⁺ (m/z 61.03) was formed as the oxidation product. The peaks at m/z 75.04 and 75.08 are assigned as protonated ethyl formate and protonated diethyl ether, respectively, and that at m/z 89.06 as protonated ethyl acetate. Copyright © 2016 John Wiley & Sons, Ltd.     

A Biofuel Cell Based on Biocatalytic Reactions of Lactate on Both Anode and Cathode Electrodes – Extracting Electrical Power from Human Sweat

Electrodes composed of carbon fibers were modified with graphene nano‐sheets in order to increase their surface area and facilitate electrochemical reactions. Electrocatalytic species, such as Meldola's blue (MB) and hemin were immobilized on the graphene surface due to their π‐π stacking and then used for electrocatalytic oxidation of NADH and reduction of H₂O₂, respectively. Further modification of these electrodes with enzymes producing NADH and H₂O₂ in situ (lactate dehydrogenase, LDH, and lactate oxidase, LOx, respectively), allowed assembling of a biofuel cell operating in the presence of lactate, oxygen and NAD⁺. The cathode of the biofuel cell required lactate and O₂ for its operation, while the anode operated in the presence of lactate and NAD⁺. Notably, both bioelectrocatalytic electrodes operated in the presence of lactate, one producing H₂O₂ in the reaction catalyzed by LOx in the presence of O₂, second producing NADH in the reaction catalyzed by LDH in the presence of NAD⁺. Both reactions were performed in the biofuel cell without separation of the cathodic and anodic solutions and with no need of a membrane. The biofuel cell was tested in solutions mimicking human sweat and then in real human sweat samples, demonstrating substantial power release being able to activate electronic devices.     

Infrared Spectrum of the Si3H8+ Cation: Evidence for a Bridged Isomer with an Asymmetric Three‐Center Two‐Electron Si?H?Si Bond

The IR spectrum of Si₃H₈⁺ ions produced in a supersonic plasma molecular beam expansion of SiH₄, He, and Ar is inferred from photodissociation of cold Si₃H₈⁺–Ar complexes. Vibrational analysis of the spectrum is consistent with a Si₃H₈⁺ structure ( 2⁺ ) obtained by a barrierless addition reaction of SiH₄ to the disilene ion (H₂Si?SiH₂⁺) in the silane plasma. In this structure, one of the electronegative H atoms of SiH₄ donates electron density into the partially filled electrophilic π orbital of the disilene cation. The resulting asymmetric Si? H? Si bridge of the 2⁺ isomer with a bond energy of approximately 60 kJ mol^?1 is characteristic for a weak three‐center two‐electron bond, which is identified by its strongly IR active asymmetric Si? H? Si stretching fundamental at about 1765 cm^?1. The observed 2⁺ isomer is calculated to be only a few kJ mol^?1 less stable than the global minimum structure of Si₃H₈⁺ ( 1⁺ ), which is derived from vertical ionization of trisilane. Although more stable, 1⁺ is not detected in the measured IR spectrum of Si₃H₈⁺–Ar, and its lower abundance in the supersonic plasma is rationalized by the production mechanism of Si₃H₈⁺ in the silane plasma, in which a high barrier between 2⁺ and 1⁺ prevents the efficient formation of 1⁺ . The potential energy surface of Si₃H₈⁺ is characterized in some detail by quantum chemical calculations. The structural, vibrational, electronic and energetic properties as well as the chemical bonding mechanism are investigated for a variety of low‐energy Si₃H₈⁺ isomers and their fragments. The weak intermolecular bonds of the Ar ligands in the Si₃H₈⁺–Ar isomers arise from dispersion and induction forces and induce only a minor perturbation of the bare Si₃H₈⁺ ions. Comparison with the potential energy surface of C₃H₈⁺ reveals the differences between the silicon and carbon species.     

Submerged Arc Breakdown of Methylene Blue in Aqueous Solutions

Low voltage, low energy submerged pulsed arcs between a pair of carbon or iron electrodes with a pulse repetition rate of 100?Hz, energies of 2.6?C192?mJ and durations of 20, 50 and 100???s were used to remove methylene blue (MB) contamination from 30?ml aqueous solutions. The MB concentration decreased exponentially with rates of 0.0006?C0.0143?s^?1 during processing with the carbon electrode pair. With the iron electrodes, the MB concentration initially decreased faster (0.030?s^?1) than with the carbon electrodes, but later saturated. However when microparticles produced with the iron electrodes were periodically filtered, the high removal rate was maintained. Under these conditions, the volume of water which can be treated per unit energy expenditure was much higher with the submerged arc than with other plasma processes. A kinetic model based on MB degradation by OH· radicals formed by the discharge was formulated. The higher initial MB removal rate with iron electrodes is explained by additional OH· production from Fenton??s reaction between Fe⁺⁺ and H₂O₂ produced by the discharge. This rate is maintained if the eroded iron particles are filtered, but if eroded iron particles accumulate, degradation slows down and stops, possibly because the iron particles catalytically decompose H₂O₂ and hence stops Fenton??s reaction, and either directly or via increased Fe⁺⁺ dissolved from the particles, scavenge the OH· radicals.     

Flue Gas Desulfurization by Dielectric Barrier Discharge

There are many problems with flue gas desulfurization by traditional gas ionization discharge, including the large size of the plasma source, high energy consumption, and the need for a traditional desulfurization method. This paper introduces oxidization of SO₂ to sulfuric acid (H₂SO₄) in a duct by reactive oxygen species (O₂ ⁺, O₃) produced by strong ionization dielectric barrier discharge. The entire plasma reaction process is completed within the duct without the use of absorbents, catalysts, or large plasma source. The reactive oxygen species O₂ ⁺ reacts with gaseous H₂O in the flue gas to generate ·OH radicals, which can oxidize trace amounts of SO₂ in large volumes of the flue gas to produce H₂SO₄. Sulfuric acid is also produced by O₃ oxidation of SO₂ to SO₃, and SO₃ reacting with gaseous H₂O in the flue gas. Experimental results showed that with a gas temperature of 22 °C and reactive oxygen species injection rate of 0.84 mg/L, the SO₂ removal rate was 81.4 %, and the SO₄ ^2? concentration in the recovered liquid H₂SO₄ reached 53.8 g/L.     

Identification of Fragment Ions by Their Kinetic Energy Gained During Dissociative Ionization by Electron Impact

A technique is described, which supports the plasma mass spectrometry to distinguish possible sources of ion peaks found in the mass spectrum of the neutral gas. The proposed method is based on the measurement of the kinetic energy which the fragment ions gain during dissociative ionization by electron impact inside the ion source of the spectrometer. This approach is of special interest for applications in plasma processes such as plasma assisted deposition or etching techniques where complicated molecules are involved. The principle of the method is demonstrated and discussed for the examination of various fragment ions as CH₃ ⁺, C₂H₂ ⁺, C₂H₃ ⁺, C₂H₅ ⁺ and CH₃O⁺ in the neutral gas spectrum of an 13.56 MHz rf discharge in an Argon-Tetraethoxysilane (TEOS) mixture.     

NH4+ Deprotonation at Interfaces Induced Reversible H3O+/NH4+ Co-insertion/Extraction

Ion insertions always involve electrode-electrolyte interface process, desolvation for instance, which determines the electrochemical kinetics. However, it′s still a challenge to achieve fast ion insertion and investigate ion transformation at interface. Herein, the interface deprotonation of NH₄⁺ and the introduced dissociation of H₂O molecules to provide sufficient H₃O⁺ to insert into materials′ structure for fast energy storages are revealed. Lewis acidic ion-NH₄⁺ can, on one hand provide H₃O⁺ itself via deprotonation, and on the other hand hydrolyze with H₂O molecules to produce H₃O⁺. In situ attenuated total reflection-Fourier transform infrared ray method probed the interface accumulation and deprotonation of NH₄⁺, and density functional theory calculations manifested that NH₄⁺ tend to thermodynamically adsorb on the surface of monoclinic VO₂, and deprotonate to provide H₃O⁺. In addition, the inserted NH₄⁺ has a positive effect for stabilizing the VO₂(B) structure. Therefore, high specific capacity (>300 mAh g⁻¹) and fast ionic insertion/extraction (<20 s) can be realized in VO₂(B) anode. This interface derivation proposes a new path for designing proton ion insertion/extraction in mild electrolyte.     

Surface Nanostructures Composed of Thiolated Cyclodextrin/Au and Fe Species: Gas‐ and Liquid‐Phase Preparation

Supramolecular surface nanostructures have application potential as functional devices. The complex combination of thiolated cyclodextrin, chemisorbed on an Au surface (Au‐S‐CD), with deposited Fe species is studied by secondary ion mass spectrometry. The Fe species are prepared by pulsed laser ablation in water and thermal effusion in vacuum. Using laser ablation in water, the solution of Fe species is dropped on Au‐S‐CD, where mass peaks at 1227 m/z, 1243 m/z, and 1260 m/z are observed and assigned to C₄₂H₆₈O₃₄SNa‐Fe⁺, C₄₂H₆₈O₃₄SK‐Fe⁺ together with C₄₂H₆₈O₃₄SNa‐FeO⁺, and C₄₂H₆₈O₃₄SK‐FeO⁺, respectively. On the other hand, laser ablation directly linked to the Au‐S‐CD surface results in desorption of CD‐S. Thermal effusion, even with a cooled surface, was negative with respect to the complex observation. Laser ablation results in the formation of a supramolecular host–guest complex of the form Au‐S‐CD‐Fe, and in the formation of an adduct of the form Au‐S‐CD‐FeO.     

Photofragmentation of 2‐Deoxy‐D‐Ribose Molecules in the Gas Phase

We have measured the synchrotron‐induced photofragmentation of isolated 2‐deoxy‐D ‐ribose molecules (C₅H₁₀O₄) at four photon energies, namely, 23.0, 15.7, 14.6, and 13.8 eV. At all photon energies above the molecule′s ionization threshold we observe the formation of a large variety of molecular cation fragments, including CH₃⁺, OH⁺, H₃O⁺, C₂H₃⁺, C₂H₄⁺, CH_xO⁺ (x=1,2,3), C₂H_xO⁺ (x=1–5), C₃H_xO⁺ (x=3–5), C₂H₄O₂⁺, C₃H_xO₂⁺ (x=1,2,4–6), C₄H₅O₂⁺, C₄H_xO₃⁺ (x=6,7), C₅H₇O₃⁺, and C₅H₈O₃⁺. The formation of these fragments shows a strong propensity of the DNA sugar to dissociate upon absorption of vacuum ultraviolet photons. The yields of particular fragments at various excitation photon energies in the range between 10 and 28 eV are also measured and their appearance thresholds determined. At all photon energies, the most intense relative yield is recorded for the m/q=57 fragment (C₃H₅O⁺), whereas a general intensity decrease is observed for all other fragments— relative to the m/q=57 fragment—with decreasing excitation energy. Thus, bond cleavage depends on the photon energy deposited in the molecule. All fragments up to m/q=75 are observed at all photon energies above their respective threshold values. Most notably, several fragmentation products, for example, CH₃⁺, H₃O⁺, C₂H₄⁺, CH₃O⁺, and C₂H₅O⁺, involve significant bond rearrangements and nuclear motion during the dissociation time. Multibond fragmentation of the sugar moiety in the sugar–phosphate backbone of DNA results in complex strand lesions and, most likely, in subsequent reactions of the neutral or charged fragments with the surrounding DNA molecules.     

A Perovskite Electrolyte That Is Stable in Moist Air for Lithium‐Ion Batteries

Solid‐oxide Li⁺ electrolytes of a rechargeable cell are generally sensitive to moisture in the air as H⁺ exchanges for the mobile Li⁺ of the electrolyte and forms insulating surface phases at the electrolyte interfaces and in the grain boundaries of a polycrystalline membrane. These surface phases dominate the total interfacial resistance of a conventional rechargeable cell with a solid–electrolyte separator. We report a new perovskite Li⁺ solid electrolyte, Li_0.38Sr_0.44Ta_0.7Hf_0.3O_2.95F_0.05, with a lithium‐ion conductivity of σ_Li=4.8×10^?4 S cm^?1 at 25 °C that does not react with water having 3≤pH≤14. The solid electrolyte with a thin Li⁺‐conducting polymer on its surface to prevent reduction of Ta⁵⁺ is wet by metallic lithium and provides low‐impedance dendrite‐free plating/stripping of a lithium anode. It is also stable upon contact with a composite polymer cathode. With this solid electrolyte, we demonstrate excellent cycling performance of an all‐solid‐state Li/LiFePO₄ cell, a Li‐S cell with a polymer‐gel cathode, and a supercapacitor.     

Characterization of Sb2O3 subjected to different ion and plasma surface treatments

This paper presents a study of Sb₂O₃ subjected to oxygen plasma and to ion beam bombardment (Ar⁺ and O₂⁺ ions of 4 keV) by x‐ray photoelectron and reflected electron energy‐loss spectroscopies. Changes in stoichiometry (i.e O/Sb ratio) and oxidation state of Sb have been detected and correlated with the chemical and ballistic effects of the beams used for alteration of the Sb₂O₃ surface. Thus, oxygen plasma treatments lead to a significant oxidation of the surface layers of this material with the formation of up to 51% Sb⁵⁺ species as found by Sb 4d curve‐fitting analysis. By contrast, O₂⁺ ion bombardment only produces a mild oxidation of the target with the formation of ～13% Sb⁵⁺ species. Argon ion bombardment induces a complex process where Sb⁵⁺ and Sb⁰ species are formed simultaneously. This result has been discussed in terms of a disproportionation reaction of the type Sb³⁺ → Sb⁵⁺ + Sb⁰. The changes in the electronic properties of the treated material are consistent with the loss upon oxidation to Sb⁵⁺ of the valence states associated to the 5s² electron pair of antimony. Approximate shapes of valence bands for Sb₂O₃ and Sb₂O₅ pure compounds have been extracted by applying factor analysis to valence band spectra of Sb₂O₃ subjected to different ion and plasma treatments. Copyright © 2003 John Wiley & Sons, Ltd.     

Excellent Stability of a Lithium‐Ion‐Conducting Solid Electrolyte upon Reversible Li+/H+ Exchange in Aqueous Solutions

Batteries with an aqueous catholyte and a Li metal anode have attracted interest owing to their exceptional energy density and high charge/discharge rate. The long‐term operation of such batteries requires that the solid electrolyte separator between the anode and aqueous solutions must be compatible with Li and stable over a wide pH range. Unfortunately, no such compound has yet been reported. In this study, an excellent stability in neutral and strongly basic solutions was observed when using the cubic Li₇La₃Zr₂O₁₂ garnet as a Li‐stable solid electrolyte. The material underwent a Li⁺/H⁺ exchange in aqueous solutions. Nevertheless, its structure remained unchanged even under a high exchange rate of 63.6 %. When treated with a 2 M LiOH solution, the Li⁺/H⁺ exchange was reversed without any structural change. These observations suggest that cubic Li₇La₃Zr₂O₁₂ is a promising candidate for the separator in aqueous lithium batteries.     

Cleaning of Porous Aluminium Titanate by Oxygen Plasma

The removal of organic contaminants from porous Al₂TiO₅ during treatment in oxygen plasma was studied by optical emission spectroscopy (OES). The samples of Al₂TiO₅ were immersed into water emulsion of mineral oil for 3 h to get soaked. Then, they were thoroughly cleaned in ultrasound to remove oil from the surface. Samples were later exposed to RF oxygen plasma at the pressure of 75 Pa. The plasma density was about 2 × 10¹⁶ m⁻³, the electron temperature was about 6 eV and the density of neutral oxygen atoms was about 2 × 10²¹ m⁻³. Optical emission spectra between 200 and 1,000 nm were measured continuously during plasma treatment. The CO peak resulting from oil oxidation reached a well-pronounced maximum between 100 and 150 s of plasma treatment. The maximum in CO corresponded well with a minimum in O peaks. Concentration of oil in the samples was estimated by energy dispersion X-ray analysis. Initially the samples showed high concentration of carbon (about 38 at.%), while after plasma treatment the carbon concentration decreased below the detection limit. The cleaning efficiency was explained by diffusion of oil towards the surface where it was removed by oxidation with oxygen radicals.     

A [Fe(CB6)] platform for binding of small molecules: Insights from DFT calculations

The viability of making [Fe(CB₆)L] (L = H₂, N₂, O₂, nitric oxide [NO^?, NO, and NO⁺], CO₂, and hydrocarbons [CH₄, C₂H₆, C₂H₄, and C₆H₆]) has been investigated by density functional theory (DFT) calculations. The complexes 2 – 18 are thermodynamically stable and may be synthesized. The small molecules are activated to some extent after complexation. Molecular orbital and ΔG calculation revealed that the molecular hydrogen and hydrocarbons can be chemically adsorbed and desorbed on [Fe(CB₆)] without any significant chemical modification and therefore [Fe(CB₆)] may serve as a storage material. The N₂, O₂, and nitric oxide (NO^?, NO, and NO⁺) can be activated using [Fe(CB₆)]. Proton, carbon, boron, and nitrogen NMR chemical shift calculation predicts drastic chemical shift difference before and after the complexation of [Fe(CB₆)] with small molecules. This new findings suggest that the CB₆^2? ligand‐based complex may provide several applications in the future. © 2012 Wiley Periodicals, Inc.     

Enhanced power production of microbial fuel cells by reducing the oxygen and nitrogen functional groups of carbon cloth anode

The physicochemical properties of anode material are important for the electron transfer of anode bacteria and electricity generation of microbial fuel cells (MFCs). In this work, carbon cloth anode was pretreated with isopropanol, hydrogen peroxide (H₂O₂) and sodium hypochlorite (NaOCl) in order to reduce the anode functional groups. The influence of functional groups on the electrochemical properties of carbon cloth anode and power generation of MFCs was investigated. The anode pretreatments removed the surface sizing layer of carbon cloth and substantially reduced the contents of C‐O and pyridinic/pyrrolic N groups on the anode. Electrochemical impedance spectroscopy and cyclic voltammetry analyses of the biofilm‐matured anodes revealed an enhanced electrochemical electron transfer property because of the anode pretreatments. As compared with the untreated control (612 ± 6 mW m^?2), the maximum power density of an acetate‐fed single‐chamber MFC was increased by 26% (773 ± 5 mW m^?2) with the isopropanol treated anode. Additional treatment with H₂O₂ and NaOCl further increased the maximum power output to 844 ± 5 mW m^?2 and 831 ± 4 mWm^?2. A nearly inverse liner relationship was observed between the contents of C‐O and pyridinic/pyrrolic N groups on anodes and the anodic exchange current density and the power output of MFCs, indicating an adverse effect of these functional groups on the electricity production of anodes. Results from this study will further our understanding on the microbial interaction with carbon‐based electrodes and provide an important guidance for the modification of anode materials for MFCs in future studies. Copyright © 2016 John Wiley & Sons, Ltd.     

Deposition of polysiloxane‐like nanofilms onto an aluminium alloy by plasma polymerized hexamethyldisiloxane: characterization by XPS and contact angle measurements

In this work, aluminium (Alclad 2024‐T3) substrates were cleaned by an r.f. (13.56 MHz) plasma, using argon (Ar), oxygen (O₂) and a mixture of O₂/Ar (50:50) gases. The effectiveness of plasma cleaning was checked in situ using X‐ray photoelectron spectroscopy (XPS) and ex situ using water contact angle measurements. XPS O/Al surface atomic ratios are in excellent agreement with those of the crystalline boehmite and the pseudoboehmite. Oxygen O 1s peak‐fitting was used to quantify the proportion of hydroxyl ions and the functional composition on the aluminium surface: the surface cleaned with O₂ plasma contains 50% of aluminium hydroxides, the ones cleaned with Ar plasma and with Ar/O₂ plasma contain, respectively, 25 and 37% hydroxyl ions. The binding energy separation between Al 2p and O 1s is characteristic of AlO(OH). Thin SiO_x films were subsequently deposited from a mixture of hexamethyldisiloxane (HMDSO) and oxygen. In the absence of oxygen, a hydrophobic (Θ≥ 100° ) film characteristic of polydimethylsiloxane (PDMS) is formed: polysiloxane‐like thinner films (SiO_x) are obtained with the introduction of oxygen. XPS and contact angle measurements confirmed both the composition and the structure of these films. More importantly, contact angle measurements using different liquids and interpreted with the van Oss‐Good‐Chaudhury theory allowed determination of the surface free energy of the deposited films: the calculated values of surface tension of the film formed from HMDSO/O₂: (50/50) are in excellent agreement with those of reference silica‐based materials such as a silicon wafer and cleaned glass. Copyright © 2007 John Wiley & Sons, Ltd.     

In vivo evaluation of antithrombogenicity and surface analysis of ion-implanted silicone rubber

The chemical and physical structure of ion-implanted silicone rubbers has been studied in order to analyze their blood compatibility such as reduction of platelet accumulation owing to ion implantation. H⁺₂, He⁺, C⁺, O⁺, O⁺₂, N⁺, N⁺₂, Ne⁺, Na⁺, Ar⁺, K⁺, and Kr⁺ ion implantations were performed at an energy of 150 keV with fluences between 1 × 10¹⁷ and 3 × 10¹⁷ ions/cm² at room temperature. Results of FT-IR-ATR showed that ion implantation broke the original chemical bond to form new radicals such as OH, >C = O, SiH, and CH₂. The formation of these radicals depended on the ion species employed: >C = O formation by O⁺ or O⁺₂ implantation and formation of amines by N⁺ or N⁺₂ implantation. The results of Raman spectroscopy showed that ion implantation always produced a peak at near 1500 cm⁻¹, although the intensity of this peak was dependent on the ion species. The light ions like H⁺₂ and He⁺ were more effective than heavy ions in producing this peak, and O⁺₂ implantation was the most effective on producing amorphous carbon. These results indicated that >C = O and amorphous carbon, generated by O⁺₂ implantation, may improve the antithrombogenicity. The antithrombogenicity was tested by the superior vena cava (SVC) indwelling method for two days in rats with in-111-tropolone-platelets, and by the inferior vena cava (IVC) indwelling method for periods of 1–4 weeks in dogs. Results of the SVC indwelling method showed that platelet accumulation on H⁺₂ and O⁺₂ implanted specimens decreased. In particular 1 × 10¹⁷ O⁺₂/cm² implantation caused both accumulation onto specimens and the SVC to decrease. Macroscopic views of the ion-implanted IVC specimens in dogs revealed little thrombus formation. It is concluded that ion implantation into silicone rod is a useful technique to improve its antithrombogenicity.