We visualize and control molecular dynamics taking place on intermediately populated states during different sequential double ionization pathways of CO2 using a sequence of two delayed laser pulses which exhibit different peak intensities. Measured yields of CO2 (2+) and of fragment pairs CO(+)/O(+) as a function of delay between the two pulses are weakly modulated by various vibronic dynamics taking place in CO2 (+). By Fourier analysis of the modulations we identify the dynamics and show that they can be assigned to merely two double ionization pathways. We demonstrate that by reversing the sequence of the two pulses it becomes possible to control the pathway which is taken across CO2 (+) towards the final state in CO2 (2+). A comparison between the yields of CO2 (2+) and CO(+)/O(+) reveals that the modulating vibronic dynamics oscillate out-of-phase with each other, thus opening up opportunities for strong-field fragmentation control on extended time scales.
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http://dx.doi.org/10.1063/1.4939638 | DOI Listing |
Rapid Commun Mass Spectrom
March 2025
Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Canada.
Rationale: In electrospray ionization and atmospheric pressure chemical ionization, the protonation site directly guides the ion's dissociation. But what if the site of protonation is ambiguous? In this study, we explored the unimolecular reactions of protonated α- and β-pinene ions with a combination of tandem mass spectrometry and theory. Each has multiple potential protonation sites that influence their chemistry.
View Article and Find Full Text PDFAdv Sci (Weinh)
December 2024
Institute of Materials Science, Technische Universität Darmstadt, Peter-Grünberg-Str. 2, D-64287, Darmstadt, Germany.
The design of cathode/electrolyte interfaces in high-energy density Li-ion batteries is critical to protect the surface against undesirable oxygen release from the cathodes when batteries are charged to high voltage. However, the involvement of the engineered interface in the cationic and anionic redox reactions associated with (de-)lithiation is often ignored, mostly due to the difficulty to separate these processes from chemical/catalytic reactions at the cathode/electrolyte interface. Here, a new electron energy band diagrams concept is developed that includes the examination of the electrochemical- and ionization- potentials evolution upon batteries cycling.
View Article and Find Full Text PDFSe Pu
January 2025
West China School of Pharmacy, Sichuan University, Chengdu 610041, China.
Ambient mass spectrometry imaging (MSI) enables hundreds of analytes in tissue sections to be directly mapped at atmospheric pressure with minimal sample preparation. This field is currently experiencing rapid growth, with numerous reported ambient ionization techniques resulting in a "hundred flowers bloom" situation. Nanospray desorption electrospray ionization (nano-DESI), developed by the Laskin group in 2010, is a widely used liquid-extraction-based ambient ionization technique that was first used for mass spectrometry imaging of tissue in 2012.
View Article and Find Full Text PDFJ Phys Chem B
December 2024
Department of Chemistry, Indian Institute of Science Education and Research, Dr. Homi Bhabha Road, Pune 411008, India.
Understanding RNA-protein interactions is crucial for uncovering the mechanisms of cellular processes and can provide insights into the basis of various diseases, paving the way for the development of targeted therapeutic interventions. Exposure to stress conditions, such as hypoxia, leads to a drop in intracellular pH, which, in turn, alters the ionization states of amino acid residues and RNA bases, affecting the charge distribution and electrostatic interactions between RNA and proteins. In addition, pH also perturbs the structure and dynamics of proteins via the disruption of H-bonds and ionic interactions.
View Article and Find Full Text PDFMolecules
November 2024
Departamento de Biotecnología y Bioquímica, Cinvestav Irapuato, Km. 9.6 Libramiento Norte Carretera Irapuato-León, Irapuato CP 36821, GTO, Mexico.
The alkamide content and specific tissue localization in the cypselae of were investigated using gas chromatography-electron ionization mass spectrometry (GC-EIMS) and multiphoton fluorescence microscopy (MPFM). GC-EIMS analysis identified two olefinic alkamides: affinin (spilanthol) and -2-methylbutyl-2,6,8-decatrienamide. Microscopic analysis revealed that alkamides are localized within the cotyledons, and specifically compartmentalized in lipid bodies, highlighting their spatial organization.
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