The low energy range (a few 100 keV to a few MeV) primary ion mode in MeV Secondary Ion Mass Spectrometry (MeV SIMS) and its potential in exploiting the capabilities of conventional (keV) SIMS and MeV SIMS simultaneously was investigated. The aim is to see if in this energy range both types of materials, inorganic and organic, can be simultaneously analyzed. A feasibility study was conducted, first by analyzing the dependence of secondary ion yields in Indium Tin Oxide (ITO – In2O5Sn) and leucine (C6H13NO2) on various primary ion energies and charge states of Cu beam, within the scope of equal influence of electronic and nuclear stopping. Expected behavior was observed for both targets (mainly nuclear sputtering for ITO and electronic sputtering for leucine). MeV SIMS images of samples containing separate regions of Cr and leucine were obtained using both keV and MeV primary ions. Based on the image contrast and measured data, the benefit of a low energy beam is demonstrated by Cr+ intensity leveling with leucine [M+H]+ intensity, as opposed to a significant contrast at higher energy. It is estimated that by lowering the energy, leucine [M+H]+ yield efficiency lowers roughly 20 times as a price for gaining about 10 times larger efficiency of Cr+ yield, while leucine [M+H]+ yield still remains sufficiently pronounced.

Characterizing the effect of MeV ion beam irradiation on biological tissues is important for proton beam therapy, which is routinely used as a form of cancer treatment. It is also important for optimizing protocols for multimodal elemental and molecular imaging. Elemental mapping of trace elements in tissues has been carried out for a long time using nuclear microprobe analysis. However, the effect of MeV ion beams on biological samples is largely unexplored. These effects have been explored in Surrey using two mass spectrometry imaging (MSI) techniques – matrix-assisted laser desorption electrospray (MALDI) and desorption electrospray ionization (DESI). The combination of these techniques with ion beam analysis (IBA) presents a few challenges, namely substrate compatibility and de-localization of elemental markers during measurements. As such, MeV-secondary ion mass spectrometry (SIMS) is being explored as an alternative technique for molecular imaging of biological tissues. MeV SIMS, unlike conventional keV SIMS, allows the detection of intact molecules, making it a prime candidate for the molecular analysis of biological samples. This presents an opportunity to benchmark the capabilities of MeV SIMS against established and widely used techniques such as DESI and MALDI. Experiments carried out at Surrey (reported at the ICNMTA 2020) observed that proton beam-induced damage could be mitigated through the application of a MALDI matrix (employed in MALDI as an ionization aid and sample protection). Thus, the role of this matrix is explored in MeV SIMS experiments.

The low energy range (a few 100 keV to a few MeV) primary ion mode in MeV Secondary Ion Mass Spectrometry (MeV SIMS) and its potential in exploiting the capabilities of conventional (keV) SIMS and MeV SIMS simultaneously was investigated. The aim is to see if in this energy range both types of materials, inorganic and organic, can be simultaneously analyzed. A feasibility study was conducted, first by analyzing the dependence of secondary ion yields in Indium Tin Oxide (ITO – In2O5Sn) and leucine (C6H13NO2) on various primary ion energies and charge states of Cu beam, within the scope of equal influence of electronic and nuclear stopping. Expected behavior was observed for both targets (mainly nuclear sputtering for ITO and electronic sputtering for leucine). MeV SIMS images of samples containing separate regions of Cr and leucine were obtained using both keV and MeV primary ions. Based on the image contrast and measured data, the benefit of a low energy beam is demonstrated by Cr+ intensity leveling with leucine [M+H]+ intensity, as opposed to a significant contrast at higher energy. It is estimated that by lowering the energy, leucine [M+H]+ yield efficiency lowers roughly 20 times as a price for gaining about 10 times larger efficiency of Cr+ yield, while leucine [M+H]+ yield still remains sufficiently pronounced.

Common bean (Phaseolus vulgaris L.) seeds are a good source of energy, are rich in proteins and carbohydrates, minerals and vitamins (such as Fe, Zn, B-vitamin), and bioactive compounds, such as polyphenols. However, the presence of some antinutritional compounds, such as phytic acid (PA), which decreases mineral bioavailability, can limit the nutritional value of common beans. Therefore, genotypes with low PA concentrations in common beans have been generated. The increased bioavailability of Fe from LPA mutant seeds compared to the wild type common beans was shown in a stable Fe-isotope absorption study in Swiss women, indicating that the seeds of LPA common bean could be used to help remedy the Fe malnutrition in women. Within this TNA project, we spatially resolved molecular composition in LPA mutant and wild-type common beans, particularly the distribution of PA. In total, three replicates of each genotype were analyzed with MeV-SIMS at RBI. Positive and negative modes were operated for analysis of the samples and of the standard (PA). Best spectra were obtained in negative mode, in which three distinct peaks were observed in the standard (PA): 63 m/z: PO2-, 79 m/z: PO3- and 97 m/z: H2PO4-.

Common bean (Phaseolus vulgaris L.) seeds are a good source of energy, are rich in proteins and carbohydrates, minerals and vitamins (such as Fe, Zn, B-vitamin), and bioactive compounds, such as polyphenols. However, the presence of some antinutritional compounds, such as phytic acid (PA), which decreases mineral bioavailability, can limit the nutritional value of common beans. Therefore, genotypes with low PA concentrations in common beans have been generated. The increased bioavailability of Fe from LPA mutant seeds compared to the wild type common beans was shown in a stable Fe-isotope absorption study in Swiss women, indicating that the seeds of LPA common bean could be used to help remedy the Fe malnutrition in women. Within this TNA project, we spatially resolved molecular composition in LPA mutant and wild-type common beans, particularly the distribution of PA. In total, three replicates of each genotype were analyzed with MeV-SIMS at RBI. Positive and negative modes were operated for analysis of the samples and of the standard (PA). Best spectra were obtained in negative mode, in which three distinct peaks were observed in the standard (PA): 63 m/z: PO2-, 79 m/z: PO3- and 97 m/z: H2PO4-.

Characterizing the effect of MeV ion beam irradiation on biological tissues is important for proton beam therapy, which is routinely used as a form of cancer treatment. It is also important for optimizing protocols for multimodal elemental and molecular imaging. Elemental mapping of trace elements in tissues has been carried out for a long time using nuclear microprobe analysis. However, the effect of MeV ion beams on biological samples is largely unexplored. These effects have been explored in Surrey using two mass spectrometry imaging (MSI) techniques – matrix-assisted laser desorption electrospray (MALDI) and desorption electrospray ionization (DESI). The combination of these techniques with ion beam analysis (IBA) presents a few challenges, namely substrate compatibility and de-localization of elemental markers during measurements. As such, MeV-secondary ion mass spectrometry (SIMS) is being explored as an alternative technique for molecular imaging of biological tissues. MeV SIMS, unlike conventional keV SIMS, allows the detection of intact molecules, making it a prime candidate for the molecular analysis of biological samples. This presents an opportunity to benchmark the capabilities of MeV SIMS against established and widely used techniques such as DESI and MALDI. Experiments carried out at Surrey (reported at the ICNMTA 2020) observed that proton beam-induced damage could be mitigated through the application of a MALDI matrix (employed in MALDI as an ionization aid and sample protection). Thus, the role of this matrix is explored in MeV SIMS experiments.

In the forensic investigation of questioned documents, it is often very important to know the deposition order of ink traces from two different writing tools at their intersection on a paper. In the present work, intersections of inks from several writing tools were studied using optical techniques that are standardly applied for questioned documents examination in a forensic laboratory, and an accelerator-based Ion Beam Analysis (IBA) technique called Secondary Ion Mass Spectrometry using MeV ions (MeV SIMS) that is applied in an accelerator facility. MeV SIMS provides molecular information about the studied inks from writing tools, which is an added value and can be also applied for the determination of deposition order but was so far relatively rarely used in forensic studies. Aim of this paper is to compare performance of optical techniques and MeV SIMS for several combinations of intersecting lines. Cases were divided into those in which optical techniques can distinguish used inks and those which are optically completely indistinguishable. In the latter cases, we show that although mass spectra of used inks (from blue ballpoint pens) had extremely small differences, these in combination with advanced and most importantly objective multivariate algorithms could be very beneficial in resolving the deposition order at the intersection of optically indistinguishable inks. In general, MeV SIMS proved to be more efficient for oil-based inks while difficulties were encountered with water-based ones, similar to optical methods.

In the forensic investigation of questioned documents, it is often very important to know the deposition order of ink traces from two different writing tools at their intersection on a paper. In the present work, intersections of inks from several writing tools were studied using optical techniques that are standardly applied for questioned documents examination in a forensic laboratory, and an accelerator-based Ion Beam Analysis (IBA) technique called Secondary Ion Mass Spectrometry using MeV ions (MeV SIMS) that is applied in an accelerator facility. MeV SIMS provides molecular information about the studied inks from writing tools, which is an added value and can be also applied for the determination of deposition order but was so far relatively rarely used in forensic studies. Aim of this paper is to compare performance of optical techniques and MeV SIMS for several combinations of intersecting lines. Cases were divided into those in which optical techniques can distinguish used inks and those which are optically completely indistinguishable. In the latter cases, we show that although mass spectra of used inks (from blue ballpoint pens) had extremely small differences, these in combination with advanced and most importantly objective multivariate algorithms could be very beneficial in resolving the deposition order at the intersection of optically indistinguishable inks. In general, MeV SIMS proved to be more efficient for oil-based inks while difficulties were encountered with water-based ones, similar to optical methods.