Investigating the breakup dynamics of dihydrogen sulfide ions recombining with electrons

Abstract

This paper presents results concerning measurements of the dissociative recombination (DR) of dihydrogen sulfide ions. In combination with the ion storage ring CRYRING an imaging technique was used to investigate the breakup dynamics of the three-body channel in the DR of 32SD2(+). The two energetically available product channels S(3P) + 2D(2S) and S(1D) + 2D(2S) were both populated, with a branching fraction of the ground-state channel of 0.6(0.1). Information about the angle between the two deuterium atoms upon dissociation was obtained together with information about how the available kinetic energy was distributed between the two light fragments. The recombination cross sections as functions of energy in the interval of 1 meV to 0.3 eV in the center-of-mass frame are presented for 34SH2(+). The thermal rate coefficient for the DR of 34SH2(+) was determined to be (4.8+/-1.0) x 10(-7)(T/300)(-0.72+/-0.1) cm3 s(-1) over this interval.

Sulphur-bearing molecules in diffuse molecular clouds: new results from SOFIA/GREAT and the IRAM 30 m telescope

“…References. (1) Manion et al (2013); (2) Peng et al (1999); (3) Demore et al (1997); (4) Tsuchiya et al (1994); (5) Millar et al (1986); (6) Herbst et al (1989); (7) Millar & Herbst (1990); (8) Decker et al (2001); (9) Prasad & Huntress (1980); (10) Hellberg et al 2005;(11) Abouelaziz et al (1992); (12) Kaminska et al (2008); (13) Montaigne et al (2005); (14) Kim et al (1974); (15) Anicich et al (1975); (16) …”

The dissociative recombination of fluorocarbon ions III: CF+2and CF+3

“…In the study of CF' at CRYRING, the electron energy was linearly ramped during 1 s from an energy corresponding to 1 eV collision energy (electrons moving faster than ions) through zero (velocity matched conditions) to 1 eV collision energy again (electrons slower than ions). At 1 eV collision energy, the DR cross section is very low, and the signal can be considered to come only from background processes [13]. This can therefore be used to find the exponential decay of the background and subtract it from the signal.…”

“…The DR product pulse height spectra at 0 eV collision energy of CF' and CF', recorded with these transmission grids in front of the detectors, are shown in figures l(a) and 2(a), respectively. In order to subtract the background contribution, coming mainly from rest gas collisions, spectra were recorded with the electrons either tuned to a relative energy of 1 eV (CRYRING), where the signal can be considered to come only from background processes [13], or with the electrons turned off (ASTRID). These spectra are shown in figures l(b) and 2(b).…”

REASSESSMENT OF THE DISSOCIATIVE RECOMBINATION OF N2H+AT CRYRING

“…RESULTS Figure 1 shows the retrieved absolute cross section for the DR of N 2 H + as a function of the relative kinetic energy. The data have been corrected for (1) reactions between the ions and the residual gas in the ring (Hellberg et al 2005), (2) space charge effects (DeWitt et al 1996), (3) the increase of relative kinetic energy of the reactants in the regions in which the electron beam is bent into and out of the ion beam by toroidal magnets (Lampert et al 1996), and (4) the transverse energy spread of the electrons in the interaction region, k B T ⊥ ∼ 2 meV (Danared et al 2000;Mowat et al 1995).…”