Electron impact ionization of 1-propanol

Experimental measurements of the cations created in electron impact ionization have been undertaken for the primary isomer of propanol using a Hidden Quadrupole Mass Spectrometer (EPIC 300), with a mass resolution of 1 amu. The mass spectra recorded at an incident electron energy of 70 eV reveals the relative probability of forming 50 different cations, by either direct ionization or dissociative ionization. Individual partial ionization cross sections (PICS) for 31 different cations were measured for the first time in this work, for the incident electron energy range from 10 to 100eV. Also, appearance energies (AEs) and Wannier exponents for the 16 most intense cations formed in electron collisions with 1-propanol are reported. Where possible, those results are compared to those from an earlier investigation. Total Ionization Cross Sections (TICS) were also obtained from the sum of the measured PICS, for nearly all cations measured, and are compared to relevant data reported in the literature. In addition, as a part of this study, theoretical TICS were calculated using the Binary-encounter Bethe (BEB) and independent atom model with screening corrected additivity rule (IAM - SCAR) methods. Good agreement between current measured and calculated TICSs and corresponding earlier results was typically found

Electron impact ionization of R-carvone: I. Mass spectra and appearance energies

12 pags., 5 figs., 2 tabs.The mass spectrum of R-carvone measured at 70 eV electron impact energy, in the mass region of 1–151 amu, is reported in this work. We observed in this spectrum 103 peaks associated with ionic fragmentation, 55 of them with abundances greater than 1%. The relative abundances, from this study, compare reasonably well with the corresponding values reported in the literature where such a comparison can be made. The R-carvone Ionization Energy (IE), as well as the ionic energy formation thresholds (Appearance Energy - AE) were experimentally determined for the 35 most intense cations registered in the mass spectrum, which provided values for 38 AEs and Wannier exponents (p) and the IE of this molecule. The values of the AEs and Wannier exponents produced in this work, to the best of our knowledge, are being presented for the first time to the scientific community, except for the masses of 135 amu and 150 amu. We also suggest some ionic fragmentation mechanisms and molecular structural ionic fragmentation mechanisms for R-carvone, based on the AE and p values found in this work.This work was supported by the Brazilian Conselho Nacional deDesenvolvimento Científico e Tecnologico (CNPq), Fundaç~ao deAmparoa Pesquisa do Estado de Minas Gerais (FAPEMIG) andFINEP. M.C.A.L. acknowledgesfinancial support from CNPq, whileW.A.D.P., A.C.P.F. and R.A.A.A. acknowledge their fellowships from CAPES and FAPEMIG. Some financial assistance from the Australian Research Council through grant # DP180101655 is also noted.Finally, G. Garcia thanks the CSIC project LINKA2008

Electron impact ionization of R-carvone: III. Absolute total ionization cross sections

6 pags., 2 figs., 1 tab.We report results from a joint experimental and theoretical investigation for the electron impact total ionization cross section (TICS) of R-carvone. Agreement between our measured and calculated TICS over their common energy regimes was, allowing for the measurement uncertainties, typically quite good. However when the independent atom method with screening corrected additivity rule and interference terms computation had its predicted ionization threshold energy corrected to the known experimental value, excellent agreement between it and our measured TICS was in fact found from threshold up to 50 eV.This work was supported by the Brazilian Conselho Nacional de Desenvolvimento Científico e Tecnologico (CNPq), Fundaçao deAmparo a Pesquisa do Estado de Minas Gerais and FINEP. M.C.A.L.acknowledgesfinancial support from CNPq, while W.A.D.P., A.C.P.F.and R.A.A.A. acknowledge their fellowships from CAPES and FAPEMIG. Somefinancial assistance from the Australian Research Council through grant # DP180101655 is also noted. Finally, G.García thanks the Spanish Ministerio de Ciencia, Innovacion yUniversidades for the project grants FIS 2016 -80440 and PID2019-104727RB-21 and the CSIC project LINKA20085

Absolute partial ionization cross sections for electron impact of R-carvone from threshold to 100 eV

18 pags., 5 figs., 2 tabs.Abstract: Partial ionization cross section (PICS) measurements, of the cations created through electron ionization from threshold to 100 eV, have been taken for 78 cationic fragments of R-carvone, using a HIDEN quadrupole mass spectrometer (EPIC 300) with a mass resolution of 1 amu. These PICSs correspond to the cationic fragments with the highest intensity signal registered in our R-carvone mass spectrum reported in Lopes et al. (Int. J. Mass Spectrom. 456, 116395 (2020)) and, to the best of our knowledge, are being presented here for the first time to the scientific community. We also associate the profile observed in the PICSs with some ionic fragmentation mechanisms for R-carvone, based on the appearance energy (AE) values found in Lopes et al. Graphic abstract: [Figure not available: see fulltext.]This work was supported by the Brazilian Conselho Nacional de Desenvolvimento Cientıfico e Tecnologico (CNPq), Funda¸c˜ao de Amparo `a Pesquisa do Estado de Minas Gerais (FAPEMIG) and FINEP. M.C.A.L. acknowledges financial support from CNPq, while W.A.D.P., A.C.P.F. and R.A.A.A. acknowledge their fellowships from CAPES and FAPEMIG. Some financial assistance from the Australian Research Council through grant # DP180101655 is also noted. Finally, G. Garcıa thanks the Spanish Ministerio de Ciencia, Innovacion y Universidades for the project grants FIS 2016 -80440 and the CSIC project LINKA2008

Electron scattering from 1-butanol at intermediate impact energies: Total cross sections

We report experimental measurements of the absolute total cross sections (TCSs) for electron scattering from 1-butanol at impact energies in the range 80-400 eV. Those measurements were conducted by considering the attenuation of a collimated electron beam, at a given energy, through a gas cell containing 1-butanol, at a given pressure, and through application of the Beer-Lambert law to derive the required TCS. We also report theoretical results using the Independent-Atom Model with Screening Corrected Additivity Rule and Interference approach. Those results include the TCS, the elastic integral cross section (ICS), the ionization total ICS, and the sum over all excitation process ICSs with agreement at the TCS level between our measured and calculated results being encouraging.M.C.A.L. acknowledges financial support from the Brazilian Conselho Nacional de Desenvolvimento Cientifico e Tecnológico (CNPq), Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG), and FINEP, while M.J.B. thanks CNPq for his award to enable him to visit UFJF. Some financial assistance from the Australian Research Council through Grant Nos. DP160102787 and DP180101655 is also noted. S. Ghosh acknowledges his grant from PNPD/CAPES, while G.G. thanks the Spanish Ministerio de Economia, Industria y Competitividad for his project Grant No. FIS2016-80440 and the EU Project No. FP7-ITN-ARGENT-608163

Electron impact ionisation and fragmentation of methanol and ethanol

Electron impact ionisation and dissociative ionisation of the two smallest primary alcohols have been investigated. A quadrupole mass spectrometer was used, with an internal ionising electron source resulting in an energy resolution of ∼0.8 eV. The partial ionisation cross sections (PICS) for a number of individual cations have been measured for energies between 10–100 eV. The present data compares well with previous results for methanol. Surprisingly, however, this study is the first to report individual PICS for ethanol. The sum of the present PICS for both methanol and ethanol is also compared to the total ionisation cross sections reported in the literature and are found to be in good accord. Additionally, appearance energies have been derived by fitting the Wannier equation to data measured within ∼2 eV of the cation formation threshold. However, the low energy resolution limits the precision with which these values are able to be determined. This study also establishes the validity of the data collected using the apparatus at Universidade Federal de Juiz de Fora (UFJF) and so provides a solid foundation for further studies of larger alcohols

Electron impact ionization and fragmentation of biofuels

We present in this article, a review of our recent experimental and theoretical studies published in the literature on electron impact ionization and fragmentation of the primary alcohols methanol, ethanol, 1-propanol and 1-butanol (C1–C4). We discuss the mass spectra (MS) of these alcohols, measured for the electron impact energy of 70 eV and also, total (TICS) and partial (PICS) ionization cross sections in the energy range from 10 to 100 eV, which revealed the probability of forming different cations, by either direct or dissociative ionization. These experimental TICS are summarized together with theoretical values, calculated using the Binary-encounter Bethe (BEB) and the independent atom model with the screening corrected additivity rule (IAM-SCAR) methods. Additionally, we compared data of appearance energies – AE and discussed the application of the extended Wannier theory to PICS in order to produce the ionization and ionic fragmentation thresholds for the electron impact of these alcohols