New Fragmentation Pathways in K–THF Collisions As Studied by Electron-Transfer Experiments: Negative Ion Formation

Abstract

Time-of-flight (TOF) negative ion mass spectra have been obtained in collisions of 20-100 eV neutral potassium atoms with tetrahydrofuran (C4H8O), an analogue for the sugar unit in DNA/RNA. Major enhancements in O(-) and C2H3O(-) production were observed compared with earlier dissociative electron attachment (DEA) experiments. In further contrast with DEA, no evidence was observed for dehydrogenated parent anions, and three new fragment anions were detected: CH(-), C2(-), and C2H(-). These contrasting results for potassium impact and DEA highlight significant differences in the reaction pathways initiated by the two electron delivery processes.

Bound Electron Enhanced Radiosensitisation of Nimorazole upon Charge Transfer

“…Relative to dissociative electron attachment, in electron transfer experiments, one can attain identical anions' formation with different yields, as well as other exit channels, yielding different anionic species. This has been reported several times in the past (see, e.g., [24][25][26][27][28][29][30][31][32] and references therein) and is solely due to the different collision dynamics dictating the underlying molecular mechanism responsible for negative ion formation [33]. Briefly, in atom-molecule collisions, in the vicinity of the crossing between the ionic and covalent potential energy curves governing the electron transfer process, electrons follow adiabatically the nuclear motion.…”

Experimental electron-detachment cross sections for collisions of O2− with N2 molecules in the energy range 50–7000 eV

“…Although free electron attachment processes have revealed to be an efficient way to produce such damage [3,4], they may not be sufficiently representative to completely describe the induced molecular fragmentation in biological media. Other electron-transfer processes from neutral projectiles also play relevant roles in a variety of environments, particularly in biomolecular systems [6][7][8][9][10][11].…”

Fragmentation of Tetrahydrofuran Molecules by H+, C+, and O+ Collisions at the Incident Energy Range of 25–1000 eV

“…Furthermore, several dissociation channels leading to polyatomic ionic fragments were also discussed. Almeida et al reported on negative ion formation from electron transfer in collisions of neutral potassium particles with THF in the 20–100 eV collision energy range. The most abundant fragments in negative ion TOF mass spectra were identified as O – ( m / q = 16) and C 2 H 3 O – ( m / q = 43), followed closely by CH – ( m / q = 13), CH 2 – ( m / q = 14), C 2 – ( m / q = 24), and C 2 H – ( m / q = 25) anions.…”