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Zn-based nanoparticles were precipitated into nanoporous a-SiO2/Si templates using chemical and electrochemical deposition. Nanoporous SiO2 layer on Si was created by the irradiation with fast Xe ions at cyclotron DC-60 (Astana, Kazakhstan) and further etching in HF solution. Surface morphology, pore structure and light emission of the synthesized nanocomposites were characterized. The presence of zinc oxide nanocrystals in SiO2/Si track template was confirmed by X-ray diffraction analysis.

We implanted polyimide (PI) ion-track membranes with 100 keV Ar+ to prepare a cathode for the galvanic deposition of platinum (Pt) nanocones. The surface layer of the irradiated PI films was carbonized to produce a graphitic structure at a fluence of 7.6 × 1016 ions/cm2. The carbonized surface exhibited an electric conductivity and electrochemical stability, which could be sufficient for use as a cathode. Pt nanocones were electrodeposited into the pores of the PI ion-track membrane after the implantation under the same conditions. This indicated that the Ar+ irradiation resulted in the preparation of a conductive layer on the total surface area of the ion-track membrane including the innermost regions of the pores.

We present a systematic study of the evolution of chemically etched ion tracks formed in thermally grown a-SiO2 after irradiation with 1.1 GeV and 185 MeV Au ions. The irradiated material was subsequently etched with 2.5% hydrofluoric acid (HF) for different times yielding hollow conical shaped structures of various sizes. The characterisation of these structures was carried out by synchrotron-based small-angle X-ray scattering (SAXS) measurements, enabling the determination of the geometry and dimensions of the etched conical structures with sub-nanometre precision. The results indicate that the track etching behavior is influenced by the ion energy, and that at short etching times the latent track damage in the radial direction becomes significant.

International audience; The detection threshold of poly(allyl dyglycol carbonate), PADC, for C ions is determined as 55 eV/nm in stopping power, which is significantly higher than that for proton and He ions. The stopping power is not a universal parameter for expressing the detection threshold of PADC. A new physical parameter of Radial Electron Fluence around Ion Tracks, REFIT, is proposed to describe the detection threshold of PADC. It is defined as the number density of electrons passing through the surface of a cylinder of a certain radius that is co-axial with the trajectory. Furthermore, preliminary calculations are presently being performed using the Monte Carlo simulation code of Geant4-DNA. The values of the REFIT at the detection thresholds for each ion are of the same order. Several issues affecting implementation of the REFIT paramter are discussed. These include the effects of impact parameter relating to the initial locations of secondary electrons, the effects of electron attachment below the cut off energy of 7.4 eV and the necessity of a more physically realistic medium than water for Monte Carlo simultaions.

Ion tracks created in polycarbonate foils by irradiation with 2.2 GeV Au ions were characterized using a combination of small-angle x-ray and neutron scattering (SAXS/SANS) and Fourier transform infrared spectroscopy (FTIR). The ion tracks were found to consist of a cylindrical damage core with a radius of ∼2.5 ± 0.2 nm and a relative density approximately 5% below that of the pristine polycarbonate. Upon exposure to thermal annealing between 100 and 200 °C, the tracks were observed to double in size. Simultaneously, this led to a recovery in the density of the ion track, reaching a value just below that of the pristine polymer. A mechanism is proposed that explains this behavior by diffusion of radiolysis products/material flow into the under-dense track core from the surrounding region. Treatment of the tracks with UV radiation has shown no significant change in the track structure and size.

A structure in overlapping swift heavy ion track regions in Al2O3 is studied using numerical and experimental techniques. A swift heavy ion impact is modeled with Monte-Carlo code TREKIS, describing excitation of the electronic and atomic systems, and with classical molecular dynamics tracing subsequent lattice relaxation. This combined approach is applied to simulate (predict) structure and phase transformations in tracks of heavy ions. The results of simulations are validated by high resolution transmission electron microscopy of irradiated crystals. The data obtained for 167 MeV Xe and 700 MeV Bi ion impacts in Al2O3 demonstrate that relaxation of the excess lattice energy results in formation of a cylinder-like discontinuous disordered region of about 1.8 nm and 3.4 nm in diameter, respectively. The simulation of the overlap of Xe ion tracks revealed the recovery of the pre-existing tracks, whereas higher electronic energy losses around the Bi ion trajectory lead to both damage recovery and formation of a damaged region depending on the distance between tracks, which are in a good agreement with experimental observations.

Both silicon and graphite are radiation hard materials with respect to swift heavy ions like fission fragments and cosmic rays. Recrystallisation is considered to be the main mechanism of prompt damage anneal in these two materials, resulting in negligible amounts of damage produced, even when exposed to high ion fluences. In this work we present evidence that these two materials could be susceptible to swift heavy ion irradiation effects even at low energies. In the case of silicon, ion channeling and electron microscopy measurements reveal significant recovery of pre-existing defects when exposed to a swift heavy ion beam. In the case of graphite, by using ion channeling, Raman spectroscopy and atomic force microscopy, we found that the surface of the material is more prone to irradiation damage than the bulk.

The influence of the charge state q on surface modifications induced by the impact of individual fast, heavy ions on muscovite mica was investigated. Beams of 593 MeV 197Auq+ with well-defined initial charge states over a relatively broad range of values (30 to 51) and at different irradiation geometries were used. At normal incidence, the impact features are rounded protrusions (hillocks) with ≳20 nm in diameter. At grazing angles, besides the hillocks, craters and elongated tails (up to 350 nm-long) extending along the direction of ion penetration are produced. It is shown that the impact features at normal incidence depend strongly on the initial charge state of the projectiles. This dependence is very weak at grazing angles as the ion reaches the equilibrium charge state closer to the surface. At normal ion incidence, the hillock volume scales with q3.3±0.6. This dependence stems largely from the increase in the hillock height, as a weak dependence of the diameter was observed.

International audience; Gallium nitride was irradiated with fullerene projectiles having an electronic stopping power above the threshold required to promote ion track formation. The structural and chemical changes induced by fullerene irradiation were studied through Transmission Electron Microscopy (TEM). High resolution TEM inquiries were performed to identify the structural order along the ion tracks and the strain induced in the lattice neighboring the ion tracks. The TEM investigation pointed out local amorphization inside the whole tracks and High Resolution TEM studies in the track periphery evidence local stress in the wurtzite structure. Chemical investigations were carried out by STEM Electron Energy Loss Spectroscopy (EELS) to describe the chemical order in the neighboring and inside the ion path. Ga/N stoichiometry is essentially maintained in the track core, whereas an oxidation is detected in the ion track, at the surface. Furthermore, the nitrogen k near-edge fine structure investigation reveals the encapsulation of nitrogen bubbles inside the ion tracks.

Nanomaterials 11(8), 1874 (2021). doi:10.3390/nano11081874, Published by MDPI, Basel

International audience; Nanopatterned surfaces play a key role for many applications exploiting unique features such as an enhanced surface area, long- and short-ranged morphology modulations or a spatial variation of electronic and chemical properties. Ion beam irradiation has been frequently used for nanostructuring bulk materials because it is efficient, fast, and cost-effective. In this paper we show that ion irradiation under extremely grazing incidence in conjunction with other scalable processing methods such as wet etching and thermal annealing, is a perfect tool for nanopatterning of dielectric surfaces. We demonstrate that by tuning ion energy and fluence, one can select different surface nanopattern morphologies like individual chains of nanohillocks, nanostripes, or nanoscaled ripples. Furthermore, chemical etching of the irradiated surface can be used to create a negative replica of the nanopattern as only the material making up the surface track is susceptible to the etching process and is thus removed. Also, a removal of the surface track can be achieved by thermal annealing in vacuum. All these presented strategies open up new ways for achieving control over nanoscale surface modifications using swift heavy ion beams.

Advanced electronic materials 0, 2001069 (2021). doi:10.1002/aelm.202001069, Published by Wiley-VCH Verlag GmbH & Co. KG, Weinheim

8 pags., 5 figs., This study reports phonon confinement and strain effects in the Raman spectrum of ion-irradiated and subsequently etched α-quartz. Y- and Z-cut α-quartz single crystals were irradiated at room temperature with 20-MeV Ni and 40-MeV I ions. Latent ion tracks were produced with areal densities ranging from the isolated track regime to the overlapping track regime (nominal fluences of 1 × 10, 1 × 10, and 1 × 10 ions cm). Nanowell structures were revealed after vapor etching with hydrofluoric acid (HF) aqueous solutions. A phonon confinement model was invoked to explain the observed changes in the shape of the strong Raman peak located around 463 cm. Phonon coherence lengths of the irradiated samples were determined by fitting the confinement model to the experimental data. It was found that the phonon coherence lengths (L) decreased with increasing fluence (L ~ 66 nm for samples irradiated with 1 × 10 ions cm, L ~ 58 nm at 1 × 10 ions cm, and L ~ 45 nm at 1 × 10 ions cm), suggesting that ion tracks may confine optical phonons in quartz. An additional contribution to the upshift was observed at the highest fluence. This was attributed to a contribution from lattice strain when track separations are small and the overlapping strain fields around ion tracks extend through a large volume fraction of the crystal. Through an empirical correlation, the induced stress was estimated to be on the order of 100 MPa., Nuclear Regulatory Commission FacultyDevelopment Grant, Grant/AwardNumber: NRC-HQ-84-15-G-0044;TechnofusionIII, Grant/Award Number:S2018/EMT-4437; Missouri S&T;University of Tennessee

The lattice constant and the magnetic state of CeO2 are modified by the irradiation with 200 MeV Xe ions. Under the assumption that these modifications are induced in the narrow one-dimensional region (the ion track) along the ion beam path, the dependence of the lattice constant and the saturation magnetization of CeO2 on the Xe ion fluence was analyzed by using the Poisson distribution function. The analysis reveals that the lattice constant inside the ion track, which is larger than that outside the ion track, is not affected by the overlapping of the ion track. On the other hand, the ferromagnetic state is induced inside the ion track, but the analysis shows that this ferromagnetic state is gradually destroyed due to the overlapping of the ion track. The present result implies that the Poisson distribution function is useful for describing the effect of the ion track overlapping on the ion irradiation-induced ferromagnetic state in CeO2.

Damaged regions of cylindrical shapes called ion tracks, typically in nano-meters wide and tens micro-meters long, are formed along the ion trajectories in many insulators, when high energy ions in the electronic stopping regime are injected. In most cases, the ion tracks were assumed as consequences of dense electronic energy deposition from the high energy ions, except some cases where the synergy effect with the nuclear energy deposition plays an important role. In crystalline Si (c-Si), no tracks have been observed with any monomer ions up to GeV. Tracks are formed in c-Si under 40 MeV fullerene (C60) cluster ion irradiation, which provides much higher energy deposition than monomer ions. The track diameter decreases with decreasing the ion energy until they disappear at an extrapolated value of ~ 17 MeV. However, here we report the track formation of 10 nm in diameter under C60 ion irradiation of 6 MeV, i.e., much lower than the extrapolated threshold. The diameters of 10 nm were comparable to those under 40 MeV C60 irradiation. Furthermore, the tracks formed by 6 MeV C60 irradiation consisted of damaged crystalline, while those formed by 40 MeV C60 irradiation were amorphous. The track formation was observed down to 1 MeV and probably lower with decreasing the track diameters. The track lengths were much shorter than those expected from the drop of Se below the threshold. These track formations at such low energies cannot be explained by the conventional purely electronic energy deposition mechanism, indicating another origin, e.g., the synergy effect between the electronic and nuclear energy depositions, or dual transitions of transient melting and boiling.

Here we present the biomedical sensor cell-fluorescent ion track hybrid detector4D (Cell-Fit-HD4D) to reveal individual tumor cell fate in response to microscopic ion deposition in ion beam therapy. The sensor enables long-term monitoring of single tumor cells after clinical ion beam irradiation in combination with single-cell dosimetry. Cell-Fit-HD4D is read out in-situ by conventional optical microscopy. Direct visualization of a clinical ion beam is hereby possible for the first time. The possibility to reveal fate of individual cells from a cell cohort demonstrates that our biomedical sensor clearly differs from conventional experiments that characterize cellular response after radiation on a population level. Cell-Fit-HD4D is therefore used to mimics the clinical situation of a defined tumor depth during tumor treatment by ion beam therapy. Our biomedical sensor is able to provide crucial input for current mechanistic approaches to biophysical modelling of the effect of ionizing radiation on biological matter. In the clinical context, obtaining multi-dimensional physical and biological information on individual tumor cells is an important step to further transform ion beam therapy into a highly precise discipline within oncology.

Ion-track-etched capillaries containing nanoparticles of precious metals (e.g., Pt, Au, and Ag) can be applied to plasmonic absorber materials. The precipitation of homogeneous and highly dispersed precious metal nanoparticles inside capillaries represents a key process. Ion-track-etched capillaries (diameter: 500 nm, length: 25 m) were created in polyimide film by 350 MeV Xe irradiation (3 &times, 107 ions/cm2) and chemical etching (using a sodium hypochlorite solution). The films with capillaries were immersed in an aqueous solution containing 0.1&ndash, 10 mmol/L H2PtCl6 and 0.5 vol% C2H5OH, and then irradiated with a 2 MeV electron beam up to a fluence of 1.4 &times, 1016 e/cm2. The Pt particles inside the capillaries were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The precipitation of Pt nanoparticles and isolated aggregates inside the capillaries was confirmed by TEM. The Pt nanoparticles tended to aggregate under increasing concentrations of H2PtCl6 in the aqueous solution, meanwhile, no changes in nanoparticle size were noted under increasing electron beam fluence. The results suggest that the proposed method can be used to form metal nanoparticles in nanosized capillaries with a high aspect ratio.

In this chapter, the shape elongation of nanoparticles (NPs) induced by swift heavy ions (SHIs) and optical applications are described. SHIs are very high energy ions whose energy loss processes are dominated by electronic friction. To understand the elongation mechanism and the optical properties, Sect. 5.1 describes the fundamental phenomena induced by SHI irradiation, including the point defect production, ion track formation, ion-induced compaction, core/shell ion tracks, and ion hammering. In Sect. 5.2, the properties of the shape elongation are demonstrated with important concepts of the minimum width for the elongation, the mass non-conservation, the scaling law, etc. In Sect. 5.3, the elongation mechanism, while it is still in debate, is discussed comparing with the synergy model and the thermal pressure model, after introducing the concepts of the inelastic thermal spike, two-temperature molecular dynamics. Section 5.4 reviews the optical applications of the shape elongation, including the linear dichroism, the birefringence, possible application to nanometer-thick polarizer, the second-harmonic generation microscopy, etc. In Sect. 5.5, some comments are presented about the ion tracks, which are important to understand the irradiation effects with SHIs. Finally, the elongation by MeV C60 cluster ions is described in Sect. 5.6, which is as efficient as 200 MeV Xe ions, but two orders of the magnitude lower energy.

Gallium nitride was irradiated with fullerene projectiles having an electronic stoppingpower above the threshold needed to promote ion track formation. The structural andchemical changes induced by fullerene irradiation were studied though TransmissionElectron Microscopy (TEM). High resolution TEM inquiries were performed to identifythe structural order along the ion tracks and the strain induced in the latticeneighboring the ion tracks. The TEM investigation pointed out local amorphizationinside the whole tracks and High Resolution TEM studies in the track peripheryevidence local stress in the wurtzite structure. Chemical investigations were carried outby STEM - Electron Energy Loss Spectroscopy (EELS) to describe the chemical orderin the neighboring and inside the ion path. Chemical profiles plotted across ion tracksindicate that the Ga/N stoichiometry is essentially maintained in the core track, anoxidation in the ion track periphery was also detected at the surface. Furthermore, thenitrogen k near-edge fine structure investigation reveals the encapsulation of nitrogenbubbles inside the ion tracks.

Under swift heavy ion irradiation at different fluences, the structural transformations of fullerene C70 thin film prepared by thermal evaporation are investigated. Fullerene C70 thin films are irradiated with 65 MeV Ni ions beam at different fluences from 1 × 1012 to 1 × 1014 ions/cm2. The impact of energetic ions on the fullerene molecule leads to the extinction of C70 molecule. In order to study the stability of fullerene C70 under ion irradiation, damage cross section and ion track radius of damaged cylindrical zones are determined using fullerene C70 vibration modes and their change at different fluences as recorded by Raman spectroscopy. Damage cross section is found to be 1.01 × 10−13 cm2, and ion track radius of damaged cylindrical zone is found to 1.8 nm. Fullerene C70 is completely converted from crystalline structure to amorphous carbon at a fluence of 1 × 1014 ions/cm2.

The work was performed under the grant of the Ministry of Education and Science of the Republic of Kazakhstan AP05134367 and Latvian grant lzp, ZnSe2O5 nanocrystals with an orthorhombic structure were synthesized by electrochemical deposition into a-SiO2/n-Si ion track template formed by 200 MeV Xe ion irradiation with the fluence of 107 ions/cm2. The lattice parameters determined by the X-ray diffraction and calculated by the CRYSTAL computer program package are very close to each other. It was shown that ZnSe2O5 has a direct band gap of 2.8 eV at the Γ-point. In addition, the calculated charge distribution and chemical bonds show that the crystal has an ion-covalent nature. The photoluminescence excited by photons at 300 nm has a low intensity arising mainly due to zinc and oxygen vacancies., Ministry of Education and Science of the Republic of Kazakhstan AP05134367; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART²

International audience; In this study, we represent the track response data of poly (allyl diglycol carbonate) (PADC) using the number of interactions with the stopping medium induced by secondary electrons. The N umber of I nteractions induced by S econdary E lectrons (NISE) is calculated using a Monte Carlo simulation code in Geant4-DNA. The description of the track response data given by NISE is improved compared with those proposed previously based on the stopping power and Radial Electron Fluence around Ion Tracks (REFIT). We also simulate the removal cross sections of the carbonate ester bond in PADC irradiated with protons and heavy ions (He, C, and Fe) based on the NISE. A radiation-oxidation kinetics model is combined with the estimation obtained in the present study. Discrepancies are found between the experimental results and our present simulation even after applying the radiation-oxidation kinetics model in the low stopping power region (

The CR39 polymer (poly-allyl-diglycol carbonate) is considered as a valuable instrument to register various charged particles. In the current experiment, the CR39 material was tested whether it can...

A Monte Carlo (MC) event-by-event scheme is used to calculate the temporal and spatial characteristics of electrons in silicon excited by penetrating energetic ions. The ions pass the active region of the device within ∼0.01 fs while interacting with the electrons and leaving behind them a wake of δ-electrons and their cascading secondaries. All electrons with energies Ee > 4 eV slow down to Ee ≤ 4 eV within a time interval of few femtoseconds to hundreds of picoseconds. They are then considered as stopped. Below 4 eV, their interaction with phonons becomes dominant. The results of our simulations help to understand the peculiarities of the processes which take place at these short times. It also becomes clear that one can use the inelastic thermal spike (i-TS) model only several picoseconds after the passing of the ion, and thereby avoid the deeply non-equilibrium stage of ion track evolution which is a serious problem for this model. The calculations, done using our data for the electron-phonon interactions, enable us to find the limits of using the electron-phonon coupling parameter as a constant value (independent of the electronic temperature) in the i-TS model. The latter is a key parameter of the i-TS model. Our analysis also determines the accuracy of other input parameters when the i-TS model is used in combination with molecular dynamics calculations.

Copper nanowires have been synthesized at different pH values through the template assisted electrodeposition technique using polycarbonate track-etch membranes as scaffolds. The effect of pH (0.8–2.8) of the electrolyte on structure, morphology, composition and deposition rate of copper into the pores of the template, while keeping other electrochemical conditions same, was investigated. X-ray diffraction analysis confirmed the face centered cubic phase of synthesized nanowires. With the change in pH, no shift in peaks was observed except the inclusion of an additional peak of copper oxide in nanowires synthesized at pH 2.8. The nanocrystallite size, strain, lattice stress and energy density were evaluated by X-ray analysis. Field emission scanning electron microscopy images revealed that nanowires obtained at pH 0.8, 1.1 and 1.4 showed incomplete deposition in the pores of the membrane whereas, the nanowires obtained at pH 1.7 were densely stacked, vertically aligned and uniform along the diameter and that obtained from pH 2.0–2.8 had overdeposition on their top. An increase in deposition rate was observed with the increase in pH value. The average diameter of Cu nanowires was found to be ~ 105 nm. The electrical conductivity of as-grown nanowires was observed to decrease 13-fold as the transition from bulk values to the nanosystem. Nanowires prepared at pH of 1.7 were characterized for their field-emission properties. A very large field-enhancement factor of ~ 10,855 was obtained indicating that Cu nanowires grown by reported technique shows outstanding potential as efficient field-emitters for flat panel displays.

The numbers of detected ions and the beam density dispersions at different depths of plate locations that also cover the Bragg peak region were determined by automatically searching for etched micropores in photographs of surfaces of CR-39 plastic plates exposed to 12C ions with an energy of 216 MeV/amu in a chamber for radiobiological investigations at the TWAC–ITEP accelerator–accumulator facility. A computer method for seeking etched micropores along latent ion tracks in an exposed plastic is described. Frequency distributions of detected ions over microscopic areas of each surface for eight plates have been obtained and compared using a Gaussian function.

G values of the losses of typical functional groups in PET films along boron ion tracks have been determined using FT-IR spectrometry. G value for the loss of aromatic-ring clearly increases above 270 eV/nm. Those of ester and ethylene increase around the slightly lower stopping power of 250 eV/nm. The detection thresholds are defined by determining the original points from which the evolution of etch pit starts along the latent track, when the chemical etching was progressing starting from the front surface of each incident ion trajectory. The thresholds for B, C, N, O, Ar and Kr ions have been determined for other kind of PET sheets. Values of the sensitivity at the thresholds are fairly higher at heavy ions with smaller atomic number.

Dynamic evolutions of morphology and size of swift heavy ion (SHI) induced latent tracks in muscovite mica were explored using in situ transmission electron microscopy (TEM) in this paper. Prior to the measurements, muscovite mica sheets were irradiated with Kr and Bi ions with electronic energy loss (dE/dx)e of 5.9 keV/nm and 31.5 keV/nm, respectively. It is observed in TEM micrographs that the latent tracks in mica are continuously along the cross section view of the ion tracks. The track profile is not found dramatically uniform but rather it is found slightly fluctuating for similar (dE/dx)e values. In situ TEM observation clarify that atoms in the track halo are unstable compared with the lattice atoms in the vicinity of the track. Point defects induced by the electron bombardment are generated preferentially around the track core, which results in the increased diameter of the track.

Lanthanum Halide scintillators such as lanthanum bromide (LaBr3:Ce) and lanthanum chloride (LaCl3:Ce) have been studied extensively in gamma radiation fields and have shown to be excellent gamma ray detectors. Measurements with these detectors in complex radiation fields that include neutrons, protons and heavy ions may produce some information about the radiation field. For example fast neutron (n,γ), (n,p), and (n,α) reactions produce scintillations in the crystal from the energy deposited by the resulting secondary particles. Also high energy radiation environments such as those encountered in spacecraft and high energy charged particle facilities contain protons and heavy ions with enough energy to penetrate typical scintillation detectors. The light produced in the crystal by these heavy ions is proportional to the energy deposited along the ion track. To investigate the response of LaBr3 detectors to heavy ions, a series of experiments have been carried out at the Heavy Ion Medical Accelerator in Chiba, Japan (HIMAC). Measurements with He and Si ions with various incident energies have been performed and the light output of the scintillator has been measured. The experimentally measured spectra have been compared to simulations using the particle and heavy ion transport system (PHITS) code and quenching effects have been observed in the measured spectra. The quenching of the Si ion experiments is greater than the quenching observed in the He ion experiments. The results from both simulation and experiment are presented and discussed.

Silicon ions, of energy 150 MeV and fluence ∼1012 ions/cm2, were used to register latent tracks in 40 µm thick polyimide samples. Different sizes of tracks were obtained by etching the ion irradiat...

Understanding energy dissipation in electronic and atomic subsystems and subsequent defect evolution is a scientific challenge. Separate and combined effects of electronic and nuclear energy deposition in z-cut LiTaO3 have been investigated. Irradiation of pristine LiTaO3 samples with 2 MeV Ta ions leads to amorphization due to atomic displacement damage, described by a disorder accumulation model. While 21 MeV Si ions do not produce significant damage in pristine LiTaO3, introduction of pre-existing defects sensitizes LiTaO3 to the formation of ion tracks from the electronic energy loss by 21 MeV Si ions that induce a synergistic two-stage phase transition process.Impact statementExperimental study shows that the introduction of pre-existing defects prior to high energy irradiation sensitizes LiTaO3 to ion track formation leading to a synergistic two-stage phase transition process.

We have investigated the negative and positive secondary ions emitted from ethanol droplets by 4.0-MeV C3+ impact to reveal the characteristic features of the reaction processes induced by fast heavy ions at the liquid ethanol surface. Analysis of the secondary ions was performed by time-of-flight mass spectrometry for microdroplet targets in a high vacuum environment. Fragment ions, deprotonated cluster ions, and trace amounts of the reaction product ions are observed in the negative secondary ions. The main fragment anions are C2HmO− (m = 1, 3, and 5) and C2H− generated by loss of hydrogen and oxygen atoms. The reaction product anions include deprotonated glycols, larger alcohols, and their dehydrated and dehydrogenated forms generated by secondary reactions between fragments and radicals. Furthermore, C3Hm− (m = 0–2) and C4Hm− (m = 0 and 1) are observed, which could be produced through a plasma state generated in the heavy ion track. Deprotonated ethanol cluster ions, [(EtOH)n − H]−, are observed up to about n = 25. [(EtOH)n − H]− have smaller kinetic energies than the protonated cluster ions (EtOH)nH+. This probably represents the effect of the positive Coulomb potential transiently formed in the ion track. We also discuss the size distributions and structures of the water- and CH2OH-radical-attached ethanol cluster ions.

Latent ion tracks created by energetic heavy ions (12 MeV Ti to 946 MeV Au) in single crystal SrTiO3 are investigated using Rutherford backscattering spectrometry and scanning transmission electron microscopy. The results demonstrate that pre-existing irradiation damage, introduced via elastic collision processes, interacts synergistically with the electronic energy deposition from energetic heavy ions to enhance formation of latent ion tracks. The average amorphous cross-section increases with the level of pre-damage and is linearly proportional to the electronic energy loss of the ions, with a slope dependent on the pre-damage level. For the highest energy ions (629 MeV Xe and 946 MeV Au), the tracks are continuous over the pre-damaged depth, but become discontinuous beyond the pre-damaged region. This work provides new understanding and insights on ion-solid interactions that significantly impact the interpretation of latent track formation processes, models of amorphization, and the fabrication of electro-ceramic devices.

The 6T SRAM cell with fast access speed and silicon–oxide–nitride–oxide–Silicon (SONOS) cell with nonvolatility in a 130-nm commercial-off-the-shelf (COTS) nonvolatile SRAM (NVSRAM) is exposed to heavy ion irradiation under different test conditions. In 6T SRAM mode, the influence of linear energy transfer (LET), supply voltage, ambient temperature, and periphery circuits on single-event effects (SEE) is studied and analyzed. The anomaly of multiple upsets proportion with increasing the LET value may be ascribed to the difference of ion track structure. The observed nonmonotonic relationship between the upset cross section and supply voltage can be explained by a competing mechanism of critical charge and collected charge in a sensitive node. In SONOS nonvolatile mode, the upset threshold of 60.9 MeV/(mg/cm2) and two types of errors are observed. The recoverable upset error may be caused by ion-induced discharge of nonvolatile cell and the hard error that can be annealed to vanish in room temperature probably results from the ion-induced charge trapping in oxide. The above results show that the 6T SRAM cell in this NVSRAM is vulnerable to SEE, whereas the SONOS nonvolatile cell is quite resistant. Based on the prediction of space upset rate, the potential applications and issues of this COTS NVSRAM and deep sub-micrometer SONOS process in space component are discussed.