X-ray photoelectron spectroscopy and Auger spectroscopy studies of gas-phase hexamethyldisiloxane (HMDSO) are presented. The photodissociation of this molecule is studied using various experimental coincidence techniques. We compare the fragmentation pathways observed after core ionization followed by Auger decay and after valence double photoionization of the molecule. A strongly selective production of the doubly charged tetramethyldisiloxane ion is observed in the low binding-energy regions. Theoretical calculations are carried out to tentatively explain the stability of the produced dication.
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http://dx.doi.org/10.1063/1.2136152 | DOI Listing |
Org Lett
January 2025
School of Pharmacy, Anhui Medical University, Hefei 230032, China.
Talaromeroterpenoids A-G (-), seven new 3,5-dimethylorsellinic-acid-derived meroterpenoids, and two known analogues ( and ) were isolated from the mangrove endophytic fungus sp. JNQQJ-4 by genome analysis and a molecular networking strategy. Their structures and absolute configurations were established by nuclear magnetic resonance data, high-resolution electrospray ionization mass spectrometry, and X-ray diffraction.
View Article and Find Full Text PDFJACS Au
January 2025
Department of Chemistry, Federal University of São Carlos, São Carlos 13565-905, Brazil.
The exploration of our solar system for microbial extraterrestrial life is the primary goal of several space agencies. Mars has attracted substantial attention owing to its Earth-like geological history and potential niches for microbial life. This study evaluated the suitability of the polyextremophilic fungal strain LaBioMMi 1217 as a model eukaryote for astrobiology.
View Article and Find Full Text PDFJ Am Soc Mass Spectrom
January 2025
Federal Institute for Materials Research and Testing (BAM), Richard-Willstätter-Strasse 11, D-12489 Berlin, Germany.
The end groups of three- and four-arm star-shaped polylactides (PLA) with trimethylolpropane and pentaerythritol core structures were functionalized with acetic acid. Reaction products with different degrees of functionalization were analyzed by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. Additional gradient elution liquid adsorption chromatography (GELAC) measurements were performed to determine the degree of functionalization.
View Article and Find Full Text PDFJ Chem Theory Comput
January 2025
Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany.
X-ray absorption spectroscopy (XAS) is a powerful method for exploring molecular electronic structure by exciting core electrons into higher unoccupied molecular orbitals. In this study, we present the first integration of the spin-unrestricted similarity-transformed equation-of-motion coupled cluster method (CVS-USTEOM-CCSD) for core-excited and core-ionized states into the ORCA quantum chemistry package. Using the core-valence separation (CVS) approach, we evaluate the accuracy of CVS-USTEOM-CCSD across 13 open-shell organic systems, covering over 20 core excitations with diverse spin multiplicities (doublet, triplet, and quartet).
View Article and Find Full Text PDFMass Spectrom Rev
January 2025
School of Pharmaceutical Sciences, University of Geneva, Geneva, Switzerland.
Ionization and fragmentation are at the core of mass spectrometry. But they are not necessarily separated in space, as in-source fragmentation can also occur. Here, we survey the literature published since our 2005 review on the internal energy and fragmentation in electrospray ionization sources.
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