Absolute cross sections are reported for the resonant charge-transfer reaction ${\mathrm{He}}^{+}$+He→He+${\mathrm{He}}^{+}$ at collision energies between 0.1 and 187 eV. The results, obtained using a new merging-beam apparatus at Rice University, are in agreement both with theory and with measurements made using other experimental techniques. The experimentally determined cross sections between 0.5 and 187 eV fall about a line given by ${\sigma }^{\frac{1}{2}}\left({\AA }^2\right)=5.09-2.99\mathrm{} \ln W$, where $W$ is the collision energy in eV. Considerable attention is paid to the configuration and operation of the apparatus. Tests and calculations which confirm the interpretation of the experimental data in a merging-beam experiment are discussed.

• Received 17 April 1978

DOI:https://doi.org/10.1103/PhysRevA.19.33