Intense Ion Research Articles

A method of real-time monitoring beam output stability of intense pulsed ion beam

Intense pulsed ion beam (IPIB) technology has made remarkable progress in surface modification, mixing, polishing, film deposition, and nano powder synthesis in recent years. However, the surface properties of materials under IPIB irradiation are highly sensitive to beam intensity variations. Deviations from acceptable parameter range can change the surface characteristics and increase prevalence of defects. Consequently, the real-time online monitoring of beam stability during irradiation experiments and promptly identifying of pulses exhibiting significant parameter jitter are of significance in accurately analyzing results and optimizing surface modification. This study presents a fast-response pulse X-ray diagnostic system by employing EJ-200 plastic scintillator, 9266FLB photomultiplier tube, and Tektronic TDS 2024 four-channel oscilloscope. Single particle test demonstrates that the system achieves a time resolution of 6 ns, meeting the requirements for temporal response to detecting pulse X-ray signals with a half-width of ~80 ns. By adjusting the insulation magnetic field strength of the ion diode, the IPIB output level is regulated. The diagnostic system successfully captures X-rays emitted by the external magnetic insulated ion diode operating at different output levels. Simultaneously, the ion beam energy density is measured by using an infrared camera. To mitigate diagnostic errors stemming from target ablation, the maximum energy density is controlled to be below 1.32 J/cm<sup>2</sup>. Analysis results establish a positive correlation between X-ray intensity and ion beam energy density. This relationship arises from the influence of the insulating magnetic field adjustment on the diode's operating voltage, which subsequently affects the bremsstrahlung radiant intensity and ion beam emission intensity. This correlation offers the potential for the real-time monitoring of IPIB beam output stability by utilizing X-ray signals. To further corroborate the synchronized changes in pulse X-ray intensity and ion beam intensity, Faraday cup is employed as an alternative to infrared imaging method for measuring ion current density. Results demonstrate that the amplitude of the X-ray signal changes synchronously with fluctuations of ion current density. It is worth noting that when the output intensity of ion beam deviates significantly (more than 10% of the preset value), the diagnostic system will respond quickly. These findings validate the efficacy of the proposed non-interceptive diagnostic method of real-time monitoring the intense pulsed ion beam output stability.

Thermal atomic layer etching of VO2 using sequential BCl3 and SF4 exposures: Observation of conversion, ligand-exchange, and oxidation state changes

The thermal atomic layer etching (ALE) of VO2 was demonstrated using sequential exposures of BCl3 and SF4. The VO2 etch rate measured by quartz crystal microbalance investigations at 250 °C was 2.3 Å/cycle. The mass losses during individual BCl3 and SF4 reactions were nearly self-limiting versus BCl3 and SF4 exposures. The VO2 etch rates were also dependent on temperature and varied from 0.05 Å/cycle at 150 °C to 2.3 Å/cycle at 250 °C. Fourier transform infrared (FTIR) spectroscopy studies observed VO2 etching by monitoring the decrease in absorbance from V—O stretching vibrations in the VO2 film. The FTIR spectra during the initial BCl3 exposures on the VO2 film observed the growth of absorbance from B—O stretching vibrations from B2O3 and the concurrent loss of V=O vibrational features. These changes were consistent with BCl3 converting VO2 to B2O3. The FTIR difference spectra during subsequent SF4 and BCl3 reactions also observed the growth and loss of absorbance features that were attributed to F3V=O and V—F stretching vibrations, respectively. These changes indicate that SF4 fluorinates VO2 to form a VOF3 surface layer and then BCl3 undergoes ligand-exchange with VOF3 to volatilize the VOF3 surface layer as VOCl3. There was also evidence for conversion of VO2 to B2O3 during BCl3 exposures and then removal of B2O3 by SF4 exposures. In addition, quadrupole mass spectrometry (QMS) measurements observed that the SF4 exposures produced ion intensities for SOxFyClz products in oxidation states greater than 4+. These SOxFyClz products indicate that SF4 is being oxidized and acting as a deoxyfluorination reactant. Concurrently, the QMS analysis also monitored ion intensity for S8+, S7+, S6+, S5+, and S4+. These S8 electron impact ionization products argue that SF4 oxidation occurs concurrently with SF4 reduction. The QMS also observed ion intensities corresponding to VCl4+ and VOCl3+. The presence of VOCl3+ indicates that the oxidation state of vanadium has increased to 5+ in some of the volatile etch products. The QMS also detected trichloroboroxin (B3O3Cl3) during BCl3 exposures. B3O3Cl3 is a known etch product of B2O3 during BCl3 exposures. BCl3 can convert VO2 to B2O3 and then proceed to etch the converted B2O3. Thermal VO2 ALE using BCl3 and SF4 reveals the rich complexity of surface etching reactions that can proceed by multiple pathways including conversion, ligand-exchange, and oxidation state changes.

Analysis and simulation of time-of-flight spectrum in Rb<sup>+</sup>-Rb hybrid trap

The time-of-flight mass spectrum of charged particles, which are created through two-step cw-laser photoionization of laser-cooled <sup>87</sup>Rb atoms in an ion-neutral hybrid trap, is quantitatively investigated to further facilitate the study of Rb<sup>+</sup>-Rb reactive collisions. A microchannel plate (MCP) is used to detect charged particles, and two spectral peaks corresponding to the <sup>87</sup>Rb<sup>+</sup> ions and the product <inline-formula><tex-math id="Z-20230423060254-1">\begin{document}$ \rm {}^{87}Rb_2^+ $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20222273_Z-20230423060254-1.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="9-20222273_Z-20230423060254-1.png"/></alternatives></inline-formula> of the Rb<sup>+</sup>-Rb reaction were observed in the time-of-flight spectrum, respectively. The two peaks overlapped with each other and both showed an asymmetric profile. The information about the intensity, position, and half-width of the peak for a specific ion species was derived by fitting the time-of-flight spectrum with the probability density function of the Gumbel distribution. Then the relative ion intensity was converted into absolute ion number through the following steps. The rate equation of the total number of ions, which includes the number of atoms, the calibration factor of MCP, and the effective decay rate of ions in the ion trap, was established by modeling the photoionization of atoms. Combined with the absolute number of atoms measured by absorption imaging, the calibration factor in converting the ion intensity into the ion number was derived and the relative ion intensity was converted into the absolute number of ions. This provides a method of calibrating the MCP. The reliability of our calibration method was proved by the fact that the calibration factor in converting the intensity measured by MCP into particle number is independent of the duration of photoionization, the intensity and wavelength of the ionizing laser. Moreover, in order to explain the relationship between the peak width and temperature of the corresponding ion species, the time-of-flight spectra of the ions trapped in the ion trap were simulated by using COMSOL Multiphysics. The simulation results demonstrated that the large ion kinetic energy results in a narrow spectral peak. In sum, we quantitatively analyze and simulate the time-of-flight spectrum of the photoionization of cold atoms in the Rb<sup>+</sup>-Rb hybrid trap. The absolute number of ions is obtained by the intensity of the spectral peak, and the width of the spectral peak is related to the temperature of the ions. These results lay a foundation for the in-depth analysis of the ion-atom reaction collision and charged particle temperature relaxation in the photoionization of cold atoms, and thus further elucidating the subsequent collisional dynamics of ultracold plasmas.

Energy Spectra of 3He, 4He, C, O, and Fe Suprathermal Ions per 1 AU in Particle Flows from Coronal Holes in the 23rd and 24th Solar Cycles

The energy spectra of ions 3He, 4He, C, O and Fe with energies of 0.04–2 MeV/nucleon were studied at 1 AU in solar-wind streams from near-equatorial coronal holes during the decline of solar activity in cycle 23 according to the information of the ULEIS, SWICS, and SWEPAM instruments installed onboard the ACE spacecraft. The results of this work show that suprathermal ions from coronal holes are Maxwellian solar-wind ions accelerated on the Sun and/or in interplanetary space and form a high-energy contribution to solar-wind ions (a suprathermal “tail” in the energy distribution of solar-wind ions). The energy spectra of accelerated “tail” ions have different dependences on energy, which indicates different mechanisms of their acceleration. The relationship between the intensity of suprathermal ions and the speed of the solar wind indicates the effectiveness of the acceleration of Maxwellian solar-wind ions.

Target polarization effect on energy loss of O<sup>5+</sup> ions near Bohr velocity in low density hydrogen plasma

Energy loss of ions near the Bohr velocity in plasma is one of the important topics in intense heavy ion beam driven high energy density physics and inertial confinement fusion. Based on the ions-plasma interaction experimental platform at HIRFL, this work shows the new experimental energy loss results of 1.07 MeV (~66.9 keV/u) O<sup>5+</sup> ions penetrating through a low-density partially ionized hydrogen plasma target (radio frequency plasma). The decrease of energy loss with free electron density increasing is found, which is very different from our previous result. The new experimental results are discussed by considering the theoretical models which involves the charge screening of projectiles in the partially ionized plasma and the target polarization effect-Barkas correction term. For the charge screening , the comparison between the momentum transfer under the Coulomb potential and that under the Debye potential is given, but due to the low ionization degree, the plasma screening effect seems not to be the main reason for the decrease of energy loss. For the target polarization effect , in the Bohr velocity regime, the Barkas correction term can play a key role in the ion-atom collisions. Modeling the Barkas correction term based on the proposed classical energy loss formula, the experimental data of ions in the gas target can be well fitted by the calculated values. In the partially ionized plasma, the frequent thermal electron collisions can give rise to the atomic excitation of plasma target, correspondingly the Barkas correction term changes: it decreases with the fraction of excited atoms increasing. As a result, the energy loss decreases in our experiment. In the stopping of highly charged ions in a partially ionized low-density plasma, the collisions between ions and free electrons can produce an enhanced energy loss according to previous studies. However, the target polarization effect, especially the atomic excitations, can significantly reduce the energy loss, which is observed in our experiment. Therefore, the interaction between ions and partially ionized plasma should be further studied, and the Barkas correction can be a very important term.

H2O˙+ and OH+ reactivity versus furan: experimental low energy absolute cross sections for modeling radiation damage.

Radiotherapy is one of the most widespread and efficient strategies to fight malignant tumors. Despite its broad application, the mechanisms of radiation-DNA interaction are still under investigation. Theoretical models to predict the effects of a particular delivered dose are still in their infancy due to the difficulty of simulating a real cell environment, as well as the inclusion of a large variety of secondary processes. This work reports the first experimental study of the ion-molecule reactions of the H2O˙+ and OH+ ions, produced by photoionization with synchrotron radiation, with a furan (c-C4H4O) molecule, a template for deoxyribose sugar in DNA. The present experiments, performed as a function of the collision energy of the ions and the tunable photoionization energy, provide key parameters for the theoretical modelling of the effect of radiation dose, like the absolute cross sections for producing protonated furan (furanH+) and a radical cation (furan˙+), the most abundant products, which can amount up to 200 Å2 at very low collision energies (<1.0 eV). The experimental results show that furanH+ is more fragile, indicating how the protonation of the sugar component of the DNA may favor its dissociation with possible major radiosensitizing effects. Moreover, the ring opening of furanH+ isomers and the potential energy surface of the most important fragmentation channels have been explored by molecular dynamics simulations and quantum chemistry calculations. The results show that, in the most stable isomer of furanH+, the ring opening occurs via a low energy pathway with carbon-oxygen bond cleavage, followed by the loss of neutral carbon monoxide and the formation of the allyl cation CH2CHCH2+, which instead is not observed in the fragmentation of furan˙+. At higher energies the ring opening through the carbon-carbon bond is accompanied by the loss of formaldehyde, producing HCCCH2+, the most intense fragment ion detected in the experiments. This work highlights the importance of the secondary processes, like the ion-molecule reactions at low energies in the radiation damage due to their very large cross sections, and it aims to provide benchmark data for the development of suitable models to approach this low collision energy range.

Control of nanosecond proton bunches in a magnetically insulated ion diode by resonant nuclear reactions of radiative proton capture

To calibrate the detection efficiency of a plastic scintillator that detects prompt gamma quanta from the 19F(p,αγ)16O resonant reaction of radiative proton capture and is used to control the dynamics of the arrival of protons with an energy of about 340 keV accelerated by a magnetically isolated pulsed ion diode, a change the polarity of the diode electrodes to the reverse was used, at which electron bunches were accelerated in the geometry of the Luce diode, forming virtual cathodes. The virtual cathodes in the Luce diode collectively accelerated protons to an energy of about 500 keV, the value of which was determined from the drift velocity of these virtual cathodes, while the number of such protons was determined from the activity of the 13N radionuclide induced by the 457 keV resonance of the 12C(p,γ)13N reaction. Keywords: intense pulsed ion beam, organic scintillator, prompt gamma spectrometry.

Experimental setup for interaction between highly charged ions and laser-produced plasma near Bohr velocity energy region

Ion energy loss in the interaction between highly charged ions and dense plasma near Bohr velocity energy region is one of the important physical problems in the field of high-energy density physics driven by intense heavy ion beams. Based on the 320 kV experimental platform at the Institute of Modern Physics, Chinese Academy of Sciences, a new experimental setup was built for the research of interaction between ions and laser-produced plasma near the Bohr velocity, where the ion energy loss and charge state distribution can be experimentally investigated. In this paper we introduce the new setup in detail, including the generation and controlling of pulsed ion beam ( ≥ 200 ns); the preparation of high-density laser plasma target (10&lt;sup&gt;17&lt;/sup&gt;—10&lt;sup&gt;21&lt;/sup&gt; cm&lt;sup&gt;–3&lt;/sup&gt;); the diagnostics of plasma and the developed high energy resolution ion measurement system (&lt; 1%). In the experiment, the charge distribution of Xe&lt;sup&gt;15+&lt;/sup&gt; ions with 4 MeV penetrating through the laser-produced Al plasma target is measured. The charge-state analysis device observes different results without and with the plasma, in which the outgoing Xe ion charge-state changes correspondingly from the 15+ to 10+, thus the electron capture process is believed to be dominant. In addition, the proton energy loss is also measured by using the magnetic spectrometer, showing that the experimental energy loss is about 2.0 keV, 30% higher than those theoretical predictions , which can be attributed to the fact that in the near Bohr velocity energy regime, the first-order Born approximation condition is not valid, thus the Bethe model and SSM model are inapplicable to the experimental results. In future, a systematic study will be performed based on our ions-plasma ineteraction setup, and the energy loss and charge state data will be introduced.

Impact of Conservation Processes on the Lipid Profile and Immunological Factors IL-10 and TGF-β1 in Whey Separated from Discarded Human Milk

Reuse made by the separation of whey can reduce the waste of human milk. However, the authors are not aware of the literature on treatments in human whey, made available by pasteurization holder, freeze-drying, spray drying, and high hydrostatic pressure. In this context, the present study applied treatments to human whey and evaluated their lipid and immunological quality. Among the results, a different formation in the triacylglycerol profile was evidenced after the application of spray drying and high hydrostatic pressure, while pasteurization and freezedrying presented ion intensity close to the control human whey. In addition, pasteurization proved to be adequate for lipid nutritional quality and transformation factor-β1 (TGF-β1) concentration, while an increase in interleukin-10 (IL-10) levels was promoted, between 73 and 80%, after freeze-drying, spray drying, and high hydrostatic pressure. Through the principal component analysis, it is noteworthy that the processes presented divergences in terms of the effects caused, with similarity only between pasteurization and freeze-drying in the composition of fatty acids. However, it was observed that all processes were able to maintain the nutrients. Nevertheless, it is relevant to consider individual characteristics presented and the interest in the desired quality, which can be promising as a complementary product to infant feeding.

Slow extraction modelling for NIMMS hadron therapy synchrotrons

The Next Ion Medical Machine Study (NIMMS) is an umbrella R&D programme for CERN accelerator technologies targeting advanced accelerator options for proton and light ion therapy. In collaboration with the European programme HITRIplus, one area of study is slow extraction which is required to deliver a uniform beam spill for radiotherapy treatment. Several techniques use the third-order resonance to extract hadrons; these include betatron core driven extraction and radiofrequency knock-out. Flexible simulation tools using these techniques were prepared and initially benchmarked with results from the literature that used the Proton-Ion Medical Machine Study (PIMMS) design. The limits of the current PIMMS design were then pushed to evaluate its compatibility to deliver 10x higher intensity ion beams, and using increased extraction rates.

Integration of the scattering chamber of the NUMEN experiment

The NUMEN experiment points to measure Double Charge Exchange reaction (DCE) cross sections with heavy-ion beams interacting with specific isotopes of interest for Neutrinoless Double Beta Decay process (0νββ). To achieve this, NUMEN requires a complete upgrade to MAGNEX spectrometer in INFN-LNS and a high intensity ion beam. This work focuses on the design of a new scattering chamber where the ion beam will interact with the target precisely positioned by an automatic system. The target will be cooled by a custom system based on HOPG and a cryo-cooler. The fist integration of the chamber with all its components has been done at INFN section of Turin to check compliance with the requirements and to study the procedures for the target replacement. Some results of this tests will be presented.

Effects of dielectric barrier discharge cold plasma on structure, surface hydrophobicity and allergenic properties of shrimp tropomyosin

Effects of dielectric barrier discharge (DBD) cold plasma (CP) on structure, surface hydrophobicity and allergenic properties of tropomyosin (TM) in shrimp were investigated in this study. Results showed that the molecular weight of TM increased and the protein concentration decreased with CP treatment time increased. The content of free amino acids was increased by 74.7 % and the distribution of aromatic amino acids was altered. The content of α-helix was decreased by 69 % and the surface hydrophobicity increased by 57.8 % after 20 min treatment. Allergenicity analysis showed that the IgE binding capacity decreased by 96 % after 20 min treatment, and the degranulation indexes of KU812 cells like the β-HEX release rate, the intracellular calcium ion intensity, the release of histamine and inflammatory cytokines (IL-4, TNF-α) were decreased by 32.5 %, 31.0 %, 37.3 %, 51.7 %, and 70.2 %, respectively. The current study confirmed that DBD CP could reduce the TM allergenicity through structural changes.

Effects of High-Quality Carbon Nanowalls Ionization-Assisting Substrates on Surface-Assisted Laser Desorption/Ionization Mass Spectrometry Performance.

Surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) is performed using carbon nanowalls (CNWs) for ionization-assisting substrates. The CNWs (referred to as high-quality CNWs) in the present study were grown using a radical-injection plasma-enhanced chemical vapor deposition (RI-PECVD) system with the addition of oxygen in a mixture of CH4 and H2 gases. High-quality CNWs were different with respect to crystallinity and C-OH groups, while showing similar wall-to-wall distances and a wettability comparable to CNWs (referred to as normal CNWs) grown without O2. The efficiency of SALDI was tested with both parameters of ion intensity and fragmental efficiency (survival yield (SY)) using N-benzylpyridinuim chloride (N-BP-CI). At a laser fluence of 4 mJ/cm2, normal CNWs had an SY of 0.97 and an ion intensity of 0.13, while 5-sccm-O2- high-quality CNWs had an SY of 0.89 and an ion intensity of 2.55. As a result, the sensitivity for the detection of low-molecular-weight analytes was improved with the high-quality CNWs compared to the normal CNWs, while an SY of 0.89 was maintained at a low laser fluence of 4 mJ/cm2. SALDI-MS measurements available with the high-quality CNWs ionization-assisting substrate provided high ionization and SY values.

Quantitative analysis of ToF-SIMS data of a two organic compound mixture using an autoencoder and simple artificial neural networks.

Matrix effects cause a nonlinear relationship between ion intensities and concentrations in mass spectrometry, including time-of-flight secondary ion mass spectrometry (ToF-SIMS). Here, two artificial neural network (ANN)-based methods, autoencoder-based and simple ANN methods, were employed for the quantitative and qualitative analyses of a two organic compound mixture via ToF-SIMS. The multilayer model sample contained a mixture of Irganox 1010 and Fmoc-pentafluoro-L-phenylalanine (Fmoc-PFLPA). The sample's positive and negative ion depth profiles were collected through ToF-SIMS. ToF-SIMS-derived cross-sectional image datasets were analyzed using three unsupervised methods, namely principal component analysis (PCA), multivariate curve resolution (MCR), and use of a sparse autoencoder (SAE). The supervised simple ANN method was optimized based on the spectra and validated by predicting the test dataset ratios of Irganox 1010. The results obtained using the SAE demonstrated linear calibration curves and appropriate material distribution images. The Irganox 1010 and Fmoc-PFLPA positive and negative ion datasets exhibited >0.97 correlation coefficients. The PCA and MCR results demonstrated lower linearity than that of SAE. Moreover, SAE weights indicated the ions important for each organic compound. The simple ANN method accurately predicted the ratios in the test dataset and indicated the important ions. Both the supervised and unsupervised methods based on ANN, which were employed in regulating nonlinear relationships, were effective in the quantitative and qualitative analyses of the ToF-SIMS data of the two organic compound mixtures. Regarding qualitative analysis, both ANN-based methods indicated specific ions from the molecules in the sample.

Improved 26Al and 10Be cathode performance and data analysis at KIST

Addition of a metal powder interface between solid metal cathode and sample powder was investigated for26Al and10Be analysis by accelerator mass spectrometry (AMS). Cathode quality and consistency improved, leading to more intense, stable and longer-lived ion beam currents, while cathode matrix sensitivity to powder fineness, homogeneity and precipitate to metal powder mixing ratios was reduced. Now, ratios of 1:0.75–2 for Al2O3 + Ag in Cu cathodes and 1:0.9–4 for BeO + Nb in Al or Cu cathodes are optimal. Furthermore, a survey of sputter energies showed that 5 keV–6 keV greatly increases cathode life, current stability, and cathode consumption efficiency for both BeO and Al2O3as opposed to the widely used 7 keV for High Voltage Engineering SO110 ion sources. Finally, some data flagging criteria that have recently been incorporated into the26Al and10Be internal data analysis software are explained.

Stochastic dynamic ultraviolet photofragmentation and high collision energy dissociation mass spectrometric kinetics of triadimenol and sucralose.

The major goal of the paper is to provide empirical proof of view that innovative stochastic dynamic mass spectrometric equation D″SD = 2.6388·10-17·(< I2 > - < I > 2) determines the exact analyte concentration in solution via quantifying experimental variable intensity (I) of an analyte ion per any short span of scan time of any measurement, which also appears applicable to quantify laser-induced ultraviolet photofragmentation and high energy collision dissociation mass spectrometric processes. Triadimenol (1) and sucralose (2) using positive and negative polarity are examined. Laser irradiation energy λex = 213nm is utilized. The issue is of central importance for monitoring organic micro-pollutants in surface, ground, and drinking water as well as tasks of risk assessment for environment and human health from contamination with organics. Despite the significant importance of the topic, answering the question of functional kinetic relations of such processes is by no means straightforward, so far, due to a lack of in-depth knowledge of mechanistic aspects of fragment paths of analytes in environment and foods as well as kinetics of processes under ultraviolet laser irradiation. Although there is truth in the classical theory of first-order reaction kinetics, it does not describe all kinetic data on analytes (1) and (2). A new damped sine wave functional response to a large amount of kinetics is presented. High-resolution mass spectrometric data and chemometrics are used. The study provides empirical evidence for claim that temporal behavior of mass spectrometric variable intensity under negative polarity obeys a certain scientific law written by means of equation above. It is the same for positive and negative soft-ionization mass spectrometric conditions.

Study and improvements of a radially coupled coaxial Fast Faraday cup design toward lower intensity beams

A radially coupled coaxial fast Faraday cup design was presented in Carneiro et al. [Int. J. Mod. Phys. A 34(36), 1942013 (2019)] for high-intensity non-relativistic proton beams. In this work, we discuss a modification of that design in the context of a relatively lower intensity ion beam for longitudinal charge profile measurements. Particle-in-cell and time domain electromagnetic simulations of the new design with a focus on avoiding field dilution while generating enough signal for relatively lower intensity ion beams at the upcoming High Current Injector Program at the Inter-University Accelerator Center, New Delhi [A. Roy, Curr. Sci. 76(2), 149–153 (1999); Kanjilal et al., in 3rd Asian Particle Accelerator Conference (Pohang Accelerator Laboratory, 2004), p. 73], is discussed. Profile distortions from secondary electron emission are estimated, and strategies to suppress them are discussed.

Salicylic acid elicitation improves antioxidant activity of spinach leaves by increasing phenolic content and enzyme levels

Elicitation is used in agriculture as a method of crop protection or a means to enhance nutraceutically or pharmaceutically important metabolites with the help of chemical stimuli known as elicitors. In the present experiment elicitor potential of Salicylic acid has been exploited to induce metabolic changes in spinach plant. Salicylic acid of various concentrations (1–0.01 mg/ml) were applied on spinach leaves through foliar spray and observed for biochemical changes. A multifold increase in the amount of total phenolic and total flavonoid as well as enzyme activity of peroxidase, catalase and superoxide dismutase was observed in a dose dependent manner. An increase in the antioxidant activity was observed and was shown to be correlated with the phenolic compounds. Growth parameters measured in the form of total biomass and total chlorophyll were decreased by high concentrations. Metabolite profile of the control and treated leaves was generated through ESI-MS in the positive and negative ion modes. The results showed an increase in the ion intensity peak of phenolic acids, such as gentisic acid, hydroxycinnamic acid, coumaric acid, ferulic acid and caffeic acid as well as major flavonoids of spinach plant, like kaempferol, quercetin, isorhamnetin and patulitin glycosides. Ferulic and caeffic acids were quantified by HPLC and showed an increase in their amount after elicitor treatment.

Nanometrology for evaluating rare sites for molecular homogeneity

Here, we present a methodology for identifying and characterizing nanoscale sites in extreme ultraviolet (EUV) photoresists that deviate from the mean composition by 3σ. The methodology is based on nano-projectile secondary ion mass spectrometry (SIMS) operating in the event-by-event bombardment detection mode. Nanoscale analysis is achieved by probing the surface stochastically with a suite of individual nanoprojectile impacts in which each nano-projectile samples a volume that is 10 to 15 nm in diameter and up to 10 nm in depth. For each impact, the coemitted secondary ions are collected and mass-analyzed, allowing for the analysis of colocalized moieties. We applied this technique to study the fundamental processes occurring in partially developed positive-tone EUV resists, which simulate a critical problem in EUV resists, incomplete resist removal, and production of line edge features. Such features erode device yield and have been the focus of many previous studies. Using NP-SIMS, we examined the changing molecular composition in the partially developed resist and isolated measurements with a probability below 0.3%. Grouping measurements based on the number and type of detected molecular species allowed for the identification of rare sites on the surface that deviate from the mean composition. The mass spectrometry measurements showed that both the photoacid generator (PAG) cation and anion displayed decreased homogeneity on average with increasing exposure dose. The effect was more pronounced in the sites with probabilities below 0.3%, where the measured intensity of the PAG-related ions in these sites was more than twofold larger than the mean. Thus, we attribute these nanoscale sites to aggregations of PAG within the top 10 nm of the remaining film. These results suggest that identifying and characterizing the molecular composition of rare sites may be important in defect production and film stochastics.

Emission enhancement in laser-induced breakdown spectroscopy from sample heating with a continuous-wave diode laser

In this work an affordable, energy-efficient technique to enhance the sensitivity of the laser-induced breakdown spectroscopy technique is presented. This method is based in applying the beam of a continuous wave (CW) diode laser into the spot where the focused beam of a pulsed Nd:YAG, high-power laser induces the plasma. With the present set-up the CW beam heats the sample's surface to 300 °C. It was found that pre-heating the target in this way increased the line intensity of both neutrals and ions by a factor of up to 4.5. It was also found that the plasma excitation temperature and the electron density of the heated sample did not differ significantly from those at room temperature. However the amount of ablated material did change significantly when the sample was heated, with the crater in the latter case as much as 8.9 times larger than that obtained at ambient temperature. We conclude that the intensification in the pre-heated-sample case stems not from increased electronic plasma density or temperature but rather from a larger plume size resulting from an increased amount of ablated material when the target is heated.