ELECTRON IMPACT SPECTROSCOPY OF THE FOUR- AND FIVE-MEMBERED, SATURATED HETEROCYCLIC COMPOUNDS CONTAINING NITROGEN, OXYGEN AND SULFUR¹

Abstract

The nickel and zinc complexe~ with Wen shnwrtl M I irreversildr rcdrrcion. Tho plot, of log i/(&c) vas tho pntrritiril w i s riot ti straight liue. A mixximum on tho riickcl wave was ol11.v suppressed in tho pr.ese1ic.r of 0.0080/0 Triton X-100. Thc lidf-J\ :4ve potentinls of i m h cwnplcxcs were sbifted to mort ricyativc vnlues with increasing concentratinn of the It is stablc against reducing agents (ie., ferrous iron, sulfite, ctc.) and the reduction wave is well separated from the wnvcs of nickel, lead and cdmium. BCCRIIR~ of the drawnvut wave, nnd tho lack of a suitable plateau for mcnsuring the difIuuon curieiit, the trien complcx is, however, not euit,nblc for the p a n t itative determiriat~or~ of cobalt in the prcsence of other mctds.The trivalent complex is easily prepared.the neutral products in order to obtain AHr+(ion)(2) E.

An (e, 2e + ion) study of low-energy electron-impact ionization and fragmentation of tetrahydrofuran with high mass and energy resolutions

“…Our result agrees with earlier AE studies. 12,[26][27][28] The line width of about 1.6 eV is consistent with the instrumental energy resolution (1.5 eV, FWHM) convolved with a transition width of about 0.5 eV due to vibrational-broadening. This was measured, e.g., in a high-resolution HeI photoionization study 35 and in a TPEPICO measurement.…”

“…For most ions, they are in general agreement with the reported mass spectra data which were measured for electron-impact. 12,26,27 Inconsistent results exist for the mass region around 55 amu where we observe a weak single peak. In one previous experiment, several cation peaks of much smaller intensity (below 0.5% of the most intense C 3 H + 6 peak) were observed in this mass region.…”

“…24 The electronic structure of THF has been investigated by means of electron momentum spectroscopy. 25 Information on the molecular fragmentation is obtained using mass spectrometry to identify the residual ions for electron 12,26,27 and photon interactions. 28 By scanning the projectile energy the appearance energies (AE) and, thus, the lowest energies required for production of the different ionic fragments are found.…”

Ion induced fragmentation cross-sections of DNA constituents

“…Thus, we compare our data to spectra for electron collisions with electron impact above all appearance energies. The most notable discrepancy among mass spectra for electron collisions was the appearance of mass peak around 55 amu, that was reported by Fuss [33] and Ren [30], but could not be observed by Gallegos [23], Collin [24], Dampc [25], the massbank.jp [26] and NIST [27]. The formation of that mass peak requires the simultaneous breakage of two C-O bonds, which is energetically unfavorable [31].…”

“…Kinetic energies of different mass peaks have been discussed by Ren [30] but competing dissociation channels hidden in one mass peak are not resolved in their work. From calculation of the standard enthalpy of formation, Collin attributes mass 42 to C 3 H + 6 [24], after Gallegos found C 2 H 2 O + to be more likely [23]. More recently, Scala argues that cyclic ethers predominantly react via breakage of the C-O σ-bond forming an intermediate oxy-tetramethylene diradical which then further decomposes by cleavage processes involving the C-H and C-C bonds [31].…”