Reflection time-of-flight mass spectrometer for charge-transfer cross section measurements

A new method is described that combines the production of ions by laser ablation with a reflection time-of-flight mass spectrometer for charge-transfer cross section measurements. This method allows a specific charge-transfer channel of an ion-neutral pair to be measured at energies of about 0.1 keV/amu. The metastable state ion fraction in the laser ablation ion beam is shown to be negligible. The charge-transfer cross section is determined by measuring the intensity ratio of the product ions to the parent ions after the charge-transfer reactions occur in the reflection drift tube. Verification on the apparatus is demonstrated through investigation of a single electron charge transfer of ground state C2+ ions and H-2 with the incident energy of C2+ at 3045.6(sigma=12.4) eV. Our measured cross section of 6.90(+/- 0.78) x 10(-16) cm(-2) is consistent with ground state measurements reported previously. Because of the versatility of the pulsed laser ablation ion source, this facility can be used to examine the cross sections of a variety of multiply charged ions from refractory or gaseous elements. (C) 1997 American Institute of Physics.