Ionization of acetonitrile

Abstract

The ionization of acetonitrile has been studied using both electron and photon ionization combined with coincidence detection techniques. Relative partial ionization cross sections and relative precursor-specific partial ionization cross-sections are determined for all the cations formed from single, double and triple electron ionization of CH3CN from 30-200 eV electron energy. These cross sections characterize, distinguish and quantify the positive ions formed from these levels of ionization over the electron energy range investigated. To complement these electron ionization studies, relative ion yields for the formation of single ions (both monocations and dications) and monocation cation pairs have been measured following photoionization of CH3CN from 20-42 eV using synchrotron radiation. There is a strong similarity between the photoionization data and electron ionization data.

Ionisation of PF3: absolute partial electron ionisation cross sections and the formation and reactivity of dication states

“…Using this methodology the value of f for the experiments involved in this study was found to be 0.25, a value in accord with previous determinations for our apparatus. 48 An example of the relationship between the detected ion intensities in the singles mass spectra I[X + ] and the detection efficiency f is shown by eqn (1), where N n is the number of X + ions formed via ionising events involving the loss of n electrons from a PF 3 molecule. Similar equations can be constructed for pairs and triples P 2 [X + ], P 3 [X + ], T[X + ], as shown in the literature.…”

“…The derivation of the above equations, and the other related equations for this analysis, have been described in detail in the literature. 33,48 It is possible to determine the kinetic energy release (KER) of each dicationic dissociation reaction detected in the pairs spectrum. This determination is performed by generating a TOF difference spectrum for the dissociation of interest, a histogram of intensity against (t B À t A ) as discussed above.…”

Photolysis of Fluorinated Graphites with Embedded Acetonitrile Using a White-Beam Synchrotron Radiation

“…The main product of the CH 3 CN photolysis is HCN molecules. Their preferable formation according to the path CH 3 CN→ CH + H + HCN was previously observed under the action of UV light [23], electron beam [20], and photon beam [22]. The HCN concentration after the first stage of the irradiation for 2 s is ~64% for CH 3 CN@CF 0.5 and ~57% for CH 3 CN@CF 0.3 , and it reduces to ~49% for CH 3 CN@CF 0.5 and ~47% for CH 3 CN@CF 0.3 after the 200-s exposure.…”

“…This molecule contains an element (nitrogen) that is absent in CF x and therefore is a convenient probe for studying host-guest interactions under illumination. Photolysis of acetonitrile attracts attention because these molecules are present in interstellar medium [20] and understanding of the acetonitrile fragmentation by ionizing radiation can shed light on the early stages of stars formation [21]. A study of the photolysis of gaseous acetonitrile using synchrotron radiation (SR) in the 7-22 eV range revealed the formation of CN and CH species [22].…”

“…A study of the photolysis of gaseous acetonitrile using synchrotron radiation (SR) in the 7-22 eV range revealed the formation of CN and CH species [22]. An increase of the photon energy to 42 eV allowed for additional registration of the signals from C 2 H 2 + , C 2 N + ions and a weak signal from N 2+ [20]. The ultraviolet (UV) irradiation of an H 2 O:CH 3 CN ice at 20 K yielded a large number of nitriles [23].…”