title: Generation and detection of gaseous W12O41-* and other tungstate anions by laser desorption ionization mass spectrometry.
abstract: The presence of a peak centered near m/z 2862, observed for the first time for the caged dodecatungstate radical-anion, [W12O41]-*, enables distinguishing WO2 from WO3 by Laser Desorption Ionization mass spectrometry (LDI-MS). In addition to WO2, laser irradiation of dry deposits made from aqueous ammonium paratungstate, and calcium and lead orthotungstate also produce the [W12O41]-. In contrast, spectra recorded from deposits made from aqueous Na2WO4, sodium metatungstate, and WO3, or non-aqueous calcium and lead orthotungstate, and ammonium paratungstate, failed to show the m/z 2862 peak cluster. These observations support the hypothesis that polycondensation reactions to form [W12O41]-* occur solely in the presence of water. Although dry spots are irradiated for ionization, the solvent used for sample preparation plays an important role on the chemical composition endowed to ions detected. For example, the m/z 2862 peak seen from deposits made from aqueous ammonium paratungstate, and calcium and lead orthotungstate, is absent in the spectra recorded either from pristine deposits or those derived from solutions made with organic solvents such as acetonitrile or ethanol.
authors.affiliation: Department of Civil, Environmental, and Ocean Engineering, Center for Environmental Systems, Stevens Institute of Technology, Hoboken, New Jersey 07030, USA.
authors.forename: Julius
authors.initials: J
authors.lastname: Pavlov
authors.forename: Washington
authors.initials: W
authors.lastname: Braida
authors.forename: Adebayo
authors.initials: A
authors.lastname: Ogundipe
authors.forename: Gregory
authors.initials: G
authors.lastname: O'Connor
authors.forename: Athula B
authors.initials: AB
authors.lastname: Attygalle
mesh_terms: D000097:Acetonitriles / Q000737:chemistry; D000838:Anions / Q000737:chemistry; D000431:Ethanol / Q000737:chemistry; D005740:Gases / Q000737:chemistry; D010087:Oxides / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D014414:Tungsten / Q000737:chemistry*; D017973:Tungsten Compounds / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D000097:Acetonitriles; D000838:Anions; D005740:Gases; D010087:Oxides; D017973:Tungsten Compounds; D014867:Water; D000431:Ethanol; D014414:Tungsten; C032159:acetonitrile