Charge Transfer in He+ - He → He(1s4l, l ≥ 2) - He+ Collisions in Intermediate Energy Range.

The anticrossing spectra of the helium line λ1s4l D3,F-1s2p P3=447.2 nm emitted after electron capture by He+ ions in He+-He collisions were measured for projectile energies of 10-29 keV. Furthermore, considering the excited states' time evolution, the theoretical intensity functions were calculated. The electric field and density distributions of the target He atoms in the collision volume were taken into account, and by fitting the theoretical intensities to the measured ones, the post-collisional states of the charge-transferred He atoms were determined. The results indicate that for the intermediate projectile energy range, the electronic charge distributions were asymmetric, but the electric dipole moments did not change, as in the case of the target atoms excited directly in the collisions. This result shows that the Paul trap mechanism may play an important role in the charge transfer excitation in this energy range.

Structural characterization of human milk oligosaccharides using ultrahigh performance liquid chromatography-helium charge transfer dissociation mass spectrometry.

The combination of helium charge transfer dissociation mass spectrometry (He-CTD-MS) with ultrahigh performance liquid chromatography (UHPLC) is presented for the analysis of a complex mixture of acidic and neutral human milk oligosaccharides (HMOs). The research focuses on the identification of the monosaccharide sequence, the branching patterns, the sialylation/fucosylation arrangements, and the differentiation of isomeric oligosaccharides in the mixture. Initial studies first optimized the conditions for the UHPLC separation and the He-CTD-MS conditions. Results demonstrate that He-CTD is compatible with UHPLC timescales and provides unambiguous glycosidic and cross-ring cleavages from both the reducing and the nonreducing ends, which is not typically possible using collision-induced dissociation. He-CTD produces informative fragments, including 0,3An and 0,4An ions, which have been observed with electron transfer dissociation, electron detachment dissociation, and ultraviolet photodissociation (UVPD) and are crucial for differentiating the α-2,3- versus α-2,6-linked sialic acid (Neu5Ac) residues present among sialyllacto-N-tetraose HMOs. In addition to the linkage positions, He-CTD is able to differentiate structural isomers for both sialyllacto-N-tetraoses and lacto-N-fucopentaoses structures by providing unique, unambiguous cross-ring cleavages of types 0,2An, 0,2Xn, and 1,5An while preserving most of the labile Neu5Ac and fucose groups.

Nanoarchitecture of the ventral disc of Giardia intestinalis as revealed by high-resolution scanning electron microscopy and helium ion microscopy.

The parasitic protozoan Giardia intestinalis, the causative agent of giardiasis, presents a stable and elaborated cytoskeleton, which shapes and supports several intracellular structures, including the ventral disc, the median body, the funis, and four pairs of flagella. Giardia trophozoite is the motile form that inhabits the host small intestine and attaches to epithelial cells, leading to infection. The ventral disc is considered one important element of adhesion to the intestinal cells. It is adjacent to the plasma membrane in the ventral region of the cell and consists of a spiral layer of microtubules and microribbons. In this work, we studied the organization of the cytoskeleton in the ventral disc of G. intestinalis trophozoites using high-resolution scanning electron microscopy or helium ion microscopy in plasma membrane-extracted cells. Here, we show novel morphological details about the arrangement of cross-bridges in different regions of the ventral disc. Results showed that the disc is a non-uniformly organized structure that presents specific domains, such as the margin and the ventral groove region. High-resolution scanning electron microscopy allowed observation of the labeling pattern for several anti-tubulin antibodies using secondary gold particle-labeled antibodies. Labeling in the region of the emergence of the microtubules and supernumerary microtubules using an anti-acetylated tubulin antibody was observed. Ultrastructural analysis and immunogold labeling for gamma-tubulin suggest that disc microtubules originate from a region bounded by the bands of the banded collar and merge with microtubules formed at the perinuclear region. Actin-like filaments and microtubules of the disc are associated, showing an interconnection between elements of the cytoskeleton of the trophozoite.

Hitting the Bull's Eye: Stable HeBeOH+ Complex.

It is now known that the heavier noble gases (Ng=Ar-Rn) show some varying degrees of reactivity with a gradual increase in reactivity along Ar-Rn. However, because of their very small size and very high ionization potential, helium and neon are the hardest targets to crack. Although few neon complexes are isolated at very low temperatures, helium needs very extreme situations like very high pressure. Here, we find that protonated BeO, BeOH+ can bind helium and neon spontaneously at room temperature. Therefore, extreme conditions like very low temperature and/or high pressure will not be required for their experimental isolation. The Ng-Be bond strength is very high for their heavier homologs and the bond strength shows a gradual increase from He to Rn. Moreover, the Ng-Be attractive energy is almost exclusively originated from the orbital interaction which is composed of one Ng(s/pσ )→BeOH+ σ-donation and two weaker Ng(pπ )→BeOH+ π-donations, except for helium. Helium uses its low-lying vacant 2p orbitals to accept π-electron density from BeOH+ . Previously, such electron-accepting ability of helium was used to explain a somewhat stronger helium bond than neon for neutral complexes. However, the present results indicate that such π-back donations are too weak in nature to decide any energetic trend between helium and neon.

The mystery of sub-picosecond charge transfer following irradiation of hydrated uridine monophosphate.

The early mechanisms by which ionizing rays damage biological structures by so-called direct effects are largely elusive. In a recent picosecond pulse radiolysis study of concentrated uridine monophosphate solutions [J. Ma, S. A. Denisov, J.-L. Marignier, P. Pernot, A. Adhikary, S. Seki and M. Mostafavi, J. Phys. Chem. Lett., 2018, 9, 5105], unexpected results were found regarding the oxidation of the nucleobase. The signature of the oxidized nucleobase could not be detected 5 ps after the electron pulse, but only the oxidized phosphate, raising intriguing questions about the identity of charge-transfer mechanisms that could explain the absence of U+. We address here this question by means of advanced first-principles atomistic simulations of solvated uridine monophosphate, combining Density Functional Theory (DFT) with polarizable embedding schemes. We contrast three very distinct mechanisms of charge transfer covering the atto-, femto- and pico-second timescales. We first investigate the ionization mechanism and subsequent hole/charge migrations on a timescale of attoseconds to a few femtoseconds under the frozen nuclei approximation. We then consider a nuclear-driven phosphate-to-oxidized-nucleobase electron transfer, showing that it is an uncompetitive reaction channel on the sub-picosecond timescale, despite its high exothermicity and significant electronic coupling. Finally, we show that non-adiabatic charge transfer is enabled by femtosecond nuclear relaxation after ionization. We show that electronic decoherence and the electronic coupling strength are the key parameters that determine the hopping probabilities. Our results provide important insight into the interplay between electronics and nuclear motions in the early stages of the multiscale responses of biological matter subjected to ionizing radiation.

IR action spectroscopy of glycosaminoglycan oligosaccharides.

Glycosaminoglycans (GAGs) are a physio- and pharmacologically highly relevant class of complex saccharides, possessing a linear sequence and strongly acidic character. Their repetitive linear core makes them seem structurally simple at first glance, yet differences in sulfation and epimerization lead to an enormous structural diversity with only a few GAGs having been successfully characterized to date. Recent infrared action spectroscopic experiments on sulfated mono- and disaccharide ions show great promise. Here, we assess the potential of two types of gas-phase action spectroscopy approaches in the range from 1000 to 1800 cm-1 for the structural analysis of complex GAG oligosaccharides. Synthetic tetra- and pentasaccharides were chosen as model compounds for this benchmark study. Utilizing infrared multiple photon dissociation action spectroscopy at room temperature, diagnostic bands are largely unresolved. In contrast, cryogenic infrared action spectroscopy of ions trapped in helium nanodroplets yields resolved infrared spectra with diagnostic features for monosaccharide composition and sulfation pattern. The analysis of GAGs could therefore significantly benefit from expanding the conventional MS-based toolkit with gas-phase cryogenic IR spectroscopy. Graphical abstract.

Probing the conformational landscape and thermochemistry of DNA dinucleotide anions via helium nanodroplet infrared action spectroscopy.

Isolation of biomolecules in vacuum facilitates characterization of the intramolecular interactions that determine three-dimensional structure, but experimental quantification of conformer thermochemistry remains challenging. Infrared spectroscopy of molecules trapped in helium nanodroplets is a promising methodology for the measurement of thermochemical parameters. When molecules are captured in a helium nanodroplet, the rate of cooling to an equilibrium temperature of ca. 0.4 K is generally faster than the rate of isomerization, resulting in "shock-freezing" that kinetically traps molecules in local conformational minima. This unique property enables the study of temperature-dependent conformational equilibria via infrared spectroscopy at 0.4 K, thereby avoiding the deleterious effects of spectral broadening at higher temperatures. Herein, we demonstrate the first application of this approach to ionic species by coupling electrospray ionization mass spectrometry (ESI-MS) with helium nanodroplet infrared action spectroscopy to probe the structure and thermochemistry of deprotonated DNA dinucleotides. Dinucleotide anions were generated by ESI, confined in an ion trap at temperatures between 90 and 350 K, and entrained in traversing helium nanodroplets. The infrared action spectra of the entrained ions show a strong dependence on pre-pickup ion temperature, consistent with the preservation of conformer population upon cooling to 0.4 K. Non-negative matrix factorization was utilized to identify component conformer infrared spectra and determine temperature-dependent conformer populations. Relative enthalpies and entropies of conformers were subsequently obtained from a van't Hoff analysis. IR spectra and conformer thermochemistry are compared to results from ion mobility spectrometry (IMS) and electronic structure methods. The implementation of ESI-MS as a source of dopant molecules expands the diversity of molecules accessible for thermochemical measurements, enabling the study of larger, non-volatile species.

Valine Radiolysis by H+, He+, N+, and S15+ MeV Ions.

Radiolysis of biomolecules by fast ions has interest in medical applications and astrobiology. The radiolysis of solid D-valine (0.2-2 µm thick) was performed at room temperature by 1.5 MeV H+, He+, N+, and 230 MeV S15+ ion beams. The samples were prepared by spraying/dropping valine-water-ethanol solution on ZnSe substrate. Radiolysis was monitored by infrared spectroscopy (FTIR) through the evolution of the intensity of the valine infrared 2900, 1329, 1271, 948, and 716 cm-1 bands as a function of projectile fluence. At the end of sample irradiation, residues (tholins) presenting a brownish color are observed. The dependence of the apparent (sputtering + radiolysis) destruction cross section, σd, on the beam stopping power in valine is found to follow the power law σd = aSen, with n close to 1. Thus, σd is approximately proportional to the absorbed dose. Destruction rates due to the main galactic cosmic ray species are calculated, yielding a million year half-life for solid valine in space. Data obtained in this work aim a better understanding on the radioresistance of complex organic molecules and formation of radioproducts.

Protonated and Cationic Helium Clusters.

Protonated rare gas clusters have previously been shown to display markably different structures than their pure, cationic counterparts. Here we have performed high resolution mass spectrometry measurements of protonated and pristine clusters of He containing up to 50 atoms. We identify notable differences between the magic numbers present in the two types of clusters, but in contrast to heavier rare gas clusters, neither the protonated nor pure clusters exhibit signs of icosahedral symmetries. These findings are discussed in light of results from heavier rare gases and previous theoretical work on protonated helium.

A Molecular Candle Where Few Molecules Shine: HeHHe.

HeHHe + is the only potential molecule comprised of atoms present in the early universe that is also easily observable in the infrared. This molecule has been known to exist in mass spectrometry experiments for nearly half-a-century and is likely present, but as-of-yet unconfirmed, in cold plasmas. There can exist only a handful of plausible primordial molecules in the epochs before metals (elements with nuclei heavier than 4 He as astronomers call them) were synthesized in the universe, and most of these are both rotationally and vibrationally dark. The current work brings HeHHe + into the discussion as a possible (and potentially only) molecular candle for probing high-z and any metal-deprived regions due to its exceptionally bright infrared feature previously predicted to lie at 7.43 µ m. Furthermore, the present study provides new insights into its possible formation mechanisms as well as marked stability, along with the decisive role of anharmonic zero-point energies. A new entrance pathway is proposed through the triplet state ( 3 B 1 ) of the He 2 H + molecule complexed with a hydrogen atom and a subsequent 10.90 eV charge transfer/photon emission into the linear and vibrationally-bright 1 Σ g + HeHHe + form.

Water Radical Cations in the Gas Phase: Methods and Mechanisms of Formation, Structure and Chemical Properties.

Water radical cations, (H2O)n+•, are of great research interest in both fundamental and applied sciences. Fundamental studies of water radical reactions are important to better understand the mechanisms of natural processes, such as proton transfer in aqueous solutions, the formation of hydrogen bonds and DNA damage, as well as for the discovery of new gas-phase reactions and products. In applied science, the interest in water radicals is prompted by their potential in radiobiology and as a source of primary ions for selective and sensitive chemical ionization. However, in contrast to protonated water clusters, (H2O)nH+, which are relatively easy to generate and isolate in experiments, the generation and isolation of radical water clusters, (H2O)n+•, is tremendously difficult due to their ultra-high reactivity. This review focuses on the current knowledge and unknowns regarding (H2O)n+• species, including the methods and mechanisms of their formation, structure and chemical properties.

Tailoring Photoluminescence from Si-Based Nanocrystals Prepared by Pulsed Laser Ablation in He-N2 Gas Mixtures.

Using methods of pulsed laser ablation from a silicon target in helium (He)-nitrogen (N2) gas mixtures maintained at reduced pressures (0.5-5 Torr), we fabricated substrate-supported silicon (Si) nanocrystal-based films exhibiting a strong photoluminescence (PL) emission, which depended on the He/N2 ratio. We show that, in the case of ablation in pure He gas, Si nanocrystals exhibit PL bands centered in the "red - near infrared" (maximum at 760 nm) and "green" (centered at 550 nm) spectral regions, which can be attributed to quantum-confined excitonic states in small Si nanocrystals and to local electronic states in amorphous silicon suboxide (a-SiOx) coating, respectively, while the addition of N2 leads to the generation of an intense "green-yellow" PL band centered at 580 nm. The origin of the latter band is attributed to a radiative recombination in amorphous oxynitride (a-SiNxOy) coating of Si nanocrystals. PL transients of Si nanocrystals with SiOx and a-SiNxOy coatings demonstrate nonexponential decays in the micro- and submicrosecond time scales with rates depending on nitrogen content in the mixture. After milling by ultrasound and dispersing in water, Si nanocrystals can be used as efficient non-toxic markers for bioimaging, while the observed spectral tailoring effect makes possible an adjustment of the PL emission of such markers to a concrete bioimaging task.

Developments toward the Implementation of 44Sc Production at a Medical Cyclotron.

44Sc has favorable properties for cancer diagnosis using Positron Emission Tomography (PET) making it a promising candidate for application in nuclear medicine. The implementation of its production with existing compact medical cyclotrons would mean the next essential milestone in the development of this radionuclide. While the production and application of 44Sc has been comprehensively investigated, the development of specific targetry and irradiation methods is of paramount importance. As a result, the target was optimized for the 44Ca(p,n)44Sc nuclear reaction using CaO instead of CaCO3, ensuring decrease in target radioactive degassing during irradiation and increased radionuclidic yield. Irradiations were performed at the research cyclotron at the Paul Scherrer Institute (~11 MeV, 50 µA, 90 min) and the medical cyclotron at the University of Bern (~13 MeV, 10 µA, 240 min), with yields varying from 200 MBq to 16 GBq. The development of targetry, chemical separation as well as the practical issues and implications of irradiations, are analyzed and discussed. As a proof-of-concept study, the 44Sc produced at the medical cyclotron was used for a preclinical study using a previously developed albumin-binding prostate-specific membrane antigen (PSMA) ligand. This work demonstrates the feasibility to produce 44Sc with high yields and radionuclidic purity using a medical cyclotron, equipped with a commercial solid target station.

Characterization of a trans-trans Carbonic Acid-Fluoride Complex by Infrared Action Spectroscopy in Helium Nanodroplets.

The high Lewis basicity and small ionic radius of fluoride promote the formation of strong ionic hydrogen bonds in the complexation of fluoride with protic molecules. Herein, we report that carbonic acid, a thermodynamically disfavored species that is challenging to investigate experimentally, forms a complex with fluoride in the gas phase. Intriguingly, this complex is highly stable and is observed in abundance upon nanoelectrospray ionization of an aqueous sodium fluoride solution in the presence of gas-phase carbon dioxide. We characterize the structure and properties of the carbonic acid-fluoride complex, F-(H2CO3), and its deuterated isotopologue, F-(D2CO3), by helium nanodroplet infrared action spectroscopy in the photon energy range of 390-2800 cm-1. The complex adopts a C2 v symmetry structure with the carbonic acid in a planar trans-trans conformation and both OH groups forming ionic hydrogen bonds with the fluoride. Substantial vibrational anharmonic effects are observed in the infrared spectra, most notably a strong blue shift of the symmetric hydrogen stretching fundamental relative to predictions from the harmonic approximation or vibrational second-order perturbation theory. Ab initio thermostated ring-polymer molecular dynamics simulations indicate that this blue shift originates from strong coupling between the hydrogen stretching and bending vibrations, resulting in an effective weakening of the OH···F- ionic hydrogen bonds.

Ultrasensitive Determination of Selenium and Arsenic by Modified Helium Atmospheric Pressure Glow Discharge Optical Emission Spectrometry Coupled with Hydride Generation.

We herein report the development of a compact and robust optical emission spectrometry (OES)-based technique for the ultrasensitive determination of Se and As utilizing hydride generation (HG) as the sampling technique and direct-current atmospheric pressure glow discharge in He (APGD) as the radiation source. The emission sensitivities of 50 ng mL-1 Se and As in the newly designed HG-APGD were enhanced more than 3-fold by constraining the spatial volume between two hollow-tube APGD electrodes, and the stability was significantly improved. The developed technique achieved Se and As detection limits of 0.13 and 0.087 ng mL-1, respectively, with the corresponding relative standard deviations at analyte concentrations of 50 ng mL-1 being <0.5% in both cases. Moreover, the HG-APGD-OES procedure was advantageous in that it exhibited a low power consumption (<17 W) and a low gas consumption (<100 mL min-1). Its accuracy and practicality were also demonstrated by the determination of GBW10024 (scallop) and GBW07381 (stream sediments) certified reference materials and mice blood samples. The results showed good agreement with the certified values and values obtained using inductively coupled plasma-mass spectrometry.

Separation of Isobaric Mono- and Dimethylated RGG-Repeat Peptides by Differential Ion Mobility-Mass Spectrometry.

Methylation of arginine residues in proteins, an enzyme-mediated post-translational modification (PTM), is important for mRNA processing and transport and for the regulation of many protein-protein interactions. However, proteolytic peptides resulting from alternative sites of post-translational methylation have identical masses and cannot be readily separated by standard liquid chromatography-mass spectrometry. Unlike acetylation or phosphorylation, methylation of arginine does not strongly affect the charge states of peptide ions, multiple instances of methylation can occur on a single amino acid residue, and the relative mass of the modification is <1% that of the typical proteolytic peptide. High field asymmetric waveform ion mobility spectrometry (FAIMS) is an orthogonal separation method to liquid chromatography that can rapidly separate gaseous ions prior to detection by mass spectrometry. Here, we report that FAIMS can be used to separate arginine-methylated peptides that differ by the position of a single methyl group for both mono- and dimethylated variants. Although the resolution of separation for these arginine-methylated peptides improved with increasing amounts of helium in the FAIMS carrier gas as expected, we found that the site of methylation can strongly affect the dependence of the electric field used for ion transmission on the extent of helium in the carrier gas. Thus, certain isobaric peptides can be cotransmitted at high helium concentrations whereas lower concentrations can be used for successful separations of such peptide mixtures. The capability to rapidly resolve isobaric arginine-methylated peptides should be useful in the future for the detailed analysis of protein arginine methylation in biological samples.

Comparison of in vivo lung morphometry models from 3D multiple b-value 3 He and 129 Xe diffusion-weighted MRI.

PURPOSE: To compare in vivo lung morphometry parameters derived from theoretical gas diffusion models, the cylinder model and stretched exponential model, in a range of acinar microstructural length scales encountered in healthy and diseased lungs with 3 He and 129 Xe diffusion-weighted MRI. METHODS: Three-dimensional multiple b-value 3 He and 129 Xe diffusion-weighted MRI was acquired with compressed sensing at 1.5 T from 51 and 31 subjects, respectively, including healthy volunteers, ex-smokers, idiopathic pulmonary fibrosis, and chronic obstructive pulmonary disease patients. For each subject, the stretched exponential model-derived mean diffusive length scale (LmD ) was calculated from the diffusion signal decay, and was compared with the cylinder model-derived mean chord length (Lm) and mean alveolar diameter (LAlv ) in order to determine the relationships among the different lung morphometry parameters. RESULTS: For both 3 He and 129 Xe diffusion-weighted MRI, the mean global LmD value was significantly related (P < .001) to Lm in a nonlinear power relationship, whereas the LAlv demonstrated excellent linear correlation (P < .001) with LmD . A mean bias of +1.0% and - 2.6% toward LmD was obtained for Bland-Altman analyses of 3 He and 129 Xe LmD and LAlv values, suggesting that the two morphometric parameters are equivalent measures of mean acinar dimensions. CONCLUSION: Within the experimental range of parameters considered here for both 3 He and 129 Xe, the stretched exponential model-derived LmD is related nonlinearly to cylinder model-derived Lm, and demonstrates excellent agreement with the cylinder model-derived LAlv .

Changes in the gut microbiota during and after commercial helium-oxygen saturation diving in China.

OBJECTIVES: The influence of commercial helium-oxygen saturation diving on divers' gut microbiotas was assessed to provide dietary suggestion. METHODS: Faecal samples of 47 divers working offshore were collected before (T1), during (T2) and after (T3) saturation diving. Their living and excursion depths were 55-134 metres underwater with a saturation duration of 12-31 days and PaO2 of 38-65 kPa. The faecal samples were examined through 16S ribosomal DNA amplicon sequencing based on the Illumina sequencing platform to analyse changes in the bacteria composition in the divers' guts. RESULTS: Although the α and ß diversity of the gut microbiota did not change significantly, we found that living in a hyperbaric environment of helium-oxygen saturation decreased the abundance of the genus Bifidobacterium, an obligate anaerobe, from 2.43%±3.83% at T1 to 0.79%±1.23% at T2 and 0.59%±0.79% at T3. Additionally, the abundance of some short-chain fatty acid (SCFA)-producing bacteria, such as Fusicatenibacter, Faecalibacterium, rectale group and Anaerostipes, showed a decreased trend in the order of before, during and after diving. On the contrary, the abundance of species, such as Lactococcus garvieae, Actinomyces odontolyticus, Peptoclostridium difficile, Butyricimonas virosa, Streptococcus mutans, Porphyromonas asaccharolytica and A. graevenitzii, showed an increasing trend, but most of them were pathogens. CONCLUSIONS: Occupational exposure to high pressure in a helium-oxygen saturation environment decreased the abundance of Bifidobacterium and some SCFA-producing bacteria, and increased the risk of pathogenic bacterial infection. Supplementation of the diver diet with probiotics or prebiotics during saturation diving might prevent these undesirable changes.

Deep fracture fluids isolated in the crust since the Precambrian era.

Fluids trapped as inclusions within minerals can be billions of years old and preserve a record of the fluid chemistry and environment at the time of mineralization. Aqueous fluids that have had a similar residence time at mineral interfaces and in fractures (fracture fluids) have not been previously identified. Expulsion of fracture fluids from basement systems with low connectivity occurs through deformation and fracturing of the brittle crust. The fractal nature of this process must, at some scale, preserve pockets of interconnected fluid from the earliest crustal history. In one such system, 2.8 kilometres below the surface in a South African gold mine, extant chemoautotrophic microbes have been identified in fluids isolated from the photosphere on timescales of tens of millions of years. Deep fracture fluids with similar chemistry have been found in a mine in the Timmins, Ontario, area of the Canadian Precambrian Shield. Here we show that excesses of (124)Xe, (126)Xe and (128)Xe in the Timmins mine fluids can be linked to xenon isotope changes in the ancient atmosphere and used to calculate a minimum mean residence time for this fluid of about 1.5 billion years. Further evidence of an ancient fluid system is found in (129)Xe excesses that, owing to the absence of any identifiable mantle input, are probably sourced in sediments and extracted by fluid migration processes operating during or shortly after mineralization at around 2.64 billion years ago. We also provide closed-system radiogenic noble-gas ((4)He, (21)Ne, (40)Ar, (136)Xe) residence times. Together, the different noble gases show that ancient pockets of water can survive the crustal fracturing process and remain in the crust for billions of years.

Charge Transfer, Complexes Formation and Furan Fragmentation Induced by Collisions with Low-Energy Helium Cations.

The present work focuses on unraveling the collisional processes leading to the fragmentation of the gas-phase furan molecules under the He+ and He2+ cations impact in the energy range 5-2000 eV. The presence of different mechanisms was identified by the analysis of the optical fragmentation spectra measured using the collision-induced emission spectroscopy (CIES) in conjunction with the ab initio calculations. The measurements of the fragmentation spectra of furan were performed at the different kinetic energies of both cations. In consequence, several excited products were identified by their luminescence. Among them, the emission of helium atoms excited to the 1s4d 1D2, 3D1,2,3 states was recorded. The structure of the furan molecule lacks an He atom. Therefore, observation of its emission lines is spectroscopic evidence of an impact reaction occurring via relocation of the electronic charge between interacting entities. Moreover, the recorded spectra revealed significant variations of relative band intensities of the products along with the change of the projectile charge and its velocity. In particular, at lower velocities of He+, the relative cross-sections of dissociation products have prominent resonance-like maxima. In order to elucidate the experimental results, the calculations have been performed by using a high level of quantum chemistry methods. The calculations showed that in both impact systems two collisional processes preceded fragmentation. The first one is an electron transfer from furan molecules to cations that leads to the neutralization and further excitation of the cations. The second mechanism starts from the formation of the He-C4H4O+/2+ temporary clusters before decomposition, and it is responsible for the appearance of the narrow resonances in the relative cross-section curves.