RESUMO
We have performed coincidence mass spectrometry of fragmentation of pyrene molecules by 70 eV electron impact. Ionized fragments have been mass selected using a reflectron time-of-flight mass spectrometer, and a field programmable gate array has been used for the timing of the electron and ion extraction pulses and for the event-by-event detection of the ions. Double ionization results in a number of prominent fragmentations producing two singly-ionized fragments with kinetic energies of up to a few eV. A number of fragmentations produce ions with four or more carbon atoms, which can only be formed by the breaking of at least three C-C bonds.
RESUMO
The I(2)(D'-A') luminescence in liquid C(7)F(16), C(8)F(18), C(9)F(20), and C(12)F(26) has been observed following irradiation with visible (within the I(2) X â B band region) and UV (λ < 300 nm) lasers. The band is shifted by ~2000 cm(-1) to the red relative to the gas phase and is significantly broader (fwhm ≈ 3000 cm(-1) vs 500 cm(-1) in the gas phase). Two-color excitation of other halogens in C(n)F(2n+2) solvents revealed similarly shifted and strongly broadened D'-A' bands of Br(2), IBr, and BrCl. The stability of the ion-pair states of halogens in room temperature liquids opens new experimental opportunities for condensed phase studies and may be of applied interest considering the increasing industrial applications of perfluorocarbons.