Partial cross sections for dissociative electron attachment to tetrahydrofuran reveal a dynamics-driven rich fragmentation pattern

Abstract

We report partial absolute cross sections for dissociative electron attachment (DEA) to tetrahydrofuran C 4 H 8 O. The high sensitivity of the present setup, quantitative DEA spectrometer with time-of-flight analyzer, led to identification of a number of previously unreported fragments (CH 2− ) thus revealing complex dissociation dynamics of the involved resonant states. The chemical composition of fragment anions was assigned by experiments with completely deuterated tetrahydrofuran. We also show that the dominant heavy anionic fragment with m/z = 41 is C 3 H 5 − anion rather than C 2 HO − as reported in the previous studies, in spite of the fact that formation of the latter one is energetically more favorable. The dynamics on the resonant state is thus more decisive for the reaction outcome than the asymptotic energetics. The assignment of resonances and their dynamic pathways is discussed by using comparison with recent complementary experiments that characterize electronic states of neutral and ionic tetrahydrofuran.

Electron attachment properties of c-C4F8O in different environments

“…Figure 2 (a) shows the negative ion mass spectrum recorded at the electron energy of 2 eV. A number of anionic fragments can be seen, which is expected for a molecular system of this size [18]. What is not expected, is the observation of the parent anion C 4 F 8 O − .…”

“…For measurements in the c-C 4 F 8 O/N 2 and c-C 4 F 8 O/CO 2 mixtures, the observed dependency of ν eff (N ) corresponds not to either limiting cases (i) and (ii) but to the general case (18), where N sat may be of the same order of magnitude as N (N sat ∼ N ). Therefore k quad and N sat are directly obtained from the fit of equation (18) to the measured ν eff (N ).…”

“…The shape of the O − peak is also used to determine the energy resolution of the electron beam as described in [18]. The absolute cross sections are calibrated using two independent reference values: the O − from CO 2 [19] and HCOO − from HCOOH [20].…”

“…This makes it possible to calculate k eff at at arbitrary gas pressure (provided that the pressure of c-C 4 F 8 O stays below its vapor pressure) and arbitrary low concentrations of c-C 4 F 8 O (r 1) in the buffer gases N 2 and CO 2 using equation (18). In particular the limit of k eff (N ) at low gas pressure is given by k 0 eff (r) figure 12 (a) and (b).…”

Efficient coupling of nanosecond laser pulses with the cluster medium: Generation of hydrogen‐like [C]5+ atomic ions

“…It is known that in biological media ionizing radiations liberate large numbers of low‐energy secondary electrons. Consequently, a number of electron interaction and dissociative electron attachment studies have been carried out on THF. The ionization and ionic fragmentation process of THF have also been studied in the electron energy range of 6–150 eV using mass spectrometry, and the appearance energy of selected fragment ions has been determined …”