Correlation between multiple ionization and fragmentation of ${\mathrm{C}}_2{\mathrm{H}}_6$ in charge-changing collisions with $580\text{−}\mathrm{keV}{\mathrm{C}}^{+}$

We investigate correlations between multiple ionization and fragmentation processes of the ethane molecule in collisions with $580\text{−}\mathrm{keV}{\mathrm{C}}^{+}$ ions under single-electron capture and loss conditions. Employing an electron counting technique, we directly obtain number distributions of ionized electrons, which correspond to distributions of multiple ionization probabilities of ethane. In addition, fragmentation patterns as a function of the charge state $r$ of intermediate parent ions ${\mathrm{C}}_2{{\mathrm{H}}_6}^{r+*}$ are obtained from coincidence measurements between the time of flight of the product ions and the number of electrons emitted. Fragmentation patterns in the different charge-changing conditions reveal a crucial role of the internal excitation in the fragmentation processes. Also, we provide clear evidence of strong selectivity on the parent charge state for formation of the ${{\mathrm{H}}_3}^{+}$ ion, which is exclusively generated through doubly charged parent ions ${\mathrm{C}}_2{{\mathrm{H}}_6}^{2+*}$.

Figure 1

Schematic diagram of experimental setup.

Figure 2

Two-dimensional coincidence maps between TOF of product ions and $n_e$ from ${\mathrm{C}}_2{\mathrm{H}}_6$ molecules induced by collisions of $580\text{−}\mathrm{keV}{\mathrm{C}}^{+}$ ions in the (a) $1e$ capture and (b) $1e$ loss conditions.

Figure 3

(a) Total $n_e$ spectra and fitting curves for the $1e$ capture and $1e$ loss conditions; (b) distributions of charge state of ${\mathrm{C}}_2{{\mathrm{H}}_6}^{r+*}$ transiently generated via multiple ionization (and electron capture) in collisions with $580\text{−}\mathrm{keV}{\mathrm{C}}^{+}$ ions.

Figure 4

Charge-state distributions of intermediate parent ions ${\mathrm{C}}_2{{\mathrm{H}}_6}^{r+*}$ which lead to $\mathrm{C}{{\mathrm{H}}_n}^{+}$ and ${\mathrm{C}}_2{{\mathrm{H}}_n}^{+}$ productions in the $1e$ capture and $1e$ loss conditions.

Figure 5

(a) Experimental results and fitting curves of partial $n_e$ spectra for ${{\mathrm{H}}_n}^{+}$ fragment ions $(n=1-3)$ generated in the $1e$ capture condition, (b) distributions of charge state $r$ of intermediate parent ions ${\mathrm{C}}_2{{\mathrm{H}}_6}^{r+*}$ correlated with the ${{\mathrm{H}}_n}^{+}$ productions, obtained as results of fitting procedure for the $1e$ capture and loss conditions.

Figure 6

Intensity distributions of fragment ions as a function of the charge states $r$ of parent ions ${\mathrm{C}}_2{{\mathrm{H}}_6}^{r+*}$ in (a) $1e$ capture, (b) $1e$ loss collisions, and (c) 200-eV electron collisions [33].

Figure 7

Fractions of integrated intensities of (i) ${\mathrm{C}}_2{{\mathrm{H}}_n}^{+}(n=0-6)$, (ii) $\mathrm{C}{{\mathrm{H}}_n}^{+}(n=0-3)$, and (iii) ${{\mathrm{H}}_n}^{+}(n=1-3)$ in the total intensities of product ions as a function of the parent charge state $r$ in the $1e$ capture and loss conditions.