Electron impact ionization of helium nanodroplets containing a dopant, M, can lead to the detection of both M(+) and helium-solvated cations of the type M(+)·He(n) in the gas phase. The observation of helium-doped ions, He(n)M(+), has the potential to provide information on the aftermath of the charge transfer process that leads to ion production from the helium droplet. Here we report on helium attachment to the ions from four common diatomic dopants, M = N(2), O(2), CO, and NO. For experiments carried out with droplets with an average size of 7500 helium atoms, the monomer cations show little tendency to attach and retain helium atoms on their journey out of the droplet. By way of contrast, the corresponding cluster cations, M(n)(+), where n ≥ 2, all show a clear affinity for helium and form He(m)M(n)(+) cluster ions. The stark difference between the monomer and cluster ions is attributed to more effective cooling of the latter in the aftermath of the ionization event.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1021/jp112204e | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Contribution of Nuclear Fragmentation to Dose and RBE in Carbon-Ion Radiotherapy.
Radiat Res
January 2025
Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota.
Variable relative biological effectiveness (RBE) of carbon radiotherapy may be calculated using several models, including the microdosimetric kinetic model (MKM), stochastic MKM (SMKM), repair-misrepair-fixation (RMF) model, and local effect model I (LEM), which have not been thoroughly compared. In this work, we compared how these four models handle carbon beam fragmentation, providing insight into where model differences arise. Monoenergetic and spread-out Bragg peak carbon beams incident on a water phantom were simulated using Monte Carlo.
View Article and Find Full Text PDFEnhanced Cytotoxic Effects of Cold Plasma Deposition of Topotecan: A Novel Approach for Local Cancer Drug Delivery to Glioblastoma Cells.
Cancers (Basel)
January 2025
School of Chemical and Bioprocess Engineering, University College Dublin, D04 V1W8 Dublin, Ireland.
Background/objectives: Despite the numerous advances in glioblastoma multiforme (GBM) treatment, GBM remains as the most malignant and aggressive form of brain cancer, characterized by a very poor outcome, highlighting the ongoing need for the development of new therapeutic strategies. A novel intervention using plasma-assisted local delivery of oncology drugs was developed to mediate the drug delivery, which might improve drug uptake and/or chemotherapeutic action. Topotecan (TPT), a water-soluble topoisomerase I inhibitor with major cytotoxic effects during the S-phase of the cell cycle, was selected as the candidate drug because despite its potent antitumor activity, the systemic administration to the brain is limited due to low crossing of the blood-brain barrier.
View Article and Find Full Text PDFNatural hydrogen in the volcanic-bearing sedimentary basin: Origin, conversion, and production rates.
Sci Adv
January 2025
Institute of Energy, School of Earth and Space Sciences, Peking University, Beijing 100871, China.
The origins of natural hydrogen in natural gas systems of sedimentary basins and the capacity of these systems to store hydrogen remain inadequately understood, posing crucial questions for the large-scale exploration of natural hydrogen. This study reports on the natural gas composition, stable carbon and hydrogen isotopic values, and helium isotopic values of gas samples collected from the Qingshen gas deposit within volcanic rocks of the Songliao Basin. Natural hydrogen primarily originates from water radiolysis, water-rock interactions (WRI), and mantle.
View Article and Find Full Text PDFPrediction of Cyclic O Molecules Stabilized by Helium under Pressure.
Adv Sci (Weinh)
January 2025
Center for High-Pressure Science, State Key Laboratory of Metastable Materials Science and Technology, School of Science, Yanshan University, Qinhuangdao, 066004, China.
Oxygen usually exists in the form of diatomic molecules at ambient conditions. At high pressure, it undergoes a series of phase transitions from diatomic O to O cluster and ultimately dissociates into a polymeric O spiral chain structure. Intriguingly, the commonly found cyclic hexameric molecules in other group VIA elements (e.
View Article and Find Full Text PDFTuning Fluorination of Carbon Molecular Sieve Membranes with Enhanced Reverse-Selective Hydrogen Separation From Helium.
Small
January 2025
State Key Laboratory of Fine Chemicals, Frontier Science Center for Smart Materials, School of Chemical Engineering, Dalian University of Technology, Liaoning, Dalian, 116024, China.
Membrane technology has been explored for separating helium from hydrogen in natural gas reservoirs, a process that remains extremely challenging due to the sub-Ångstrom size difference between H and He molecules. Reverse-selective H/He separation membranes offer multiple advantages over conventional helium-selective membranes, which, however, suffer from low H/He selectivity. To address this hurdle, a novel approach is proposed to tune the ultra-micropores of carbon molecular sieves (CMS) membranes through fluorination of the polymer precursor.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!