Lyman-Alpha Emission Cross Sections forH2+andD2+Collisions with the Rare Gases

Cross sections for the emission of Lyman-alpha radiation resulting from ${\mathrm{H}}_2^{+}$-and ${\mathrm{D}}_2^{+}$-rare-gas collisions have been measured in the energy range from 1 to 25 keV. Excited states of the H or D atoms which decay via the $2p-1s$ Lyman-alpha transition result from charge transfer to antibonding states of the ${\mathrm{H}}_2$ or ${\mathrm{D}}_2$ molecules or from direct excitation to antibonding states of the molecular-ion projectiles. The ${\mathrm{D}}_2^{+}$ cross sections are similar to those for ${\mathrm{H}}_2^{+}$ when plotted at equivalent projectile velocities. The results are compared with earlier measurements of the Lyman-alpha emission cross sections resulting from ${\mathrm{H}}^{+}$ and ${\mathrm{D}}^{+}$ collisions with rare gases and with the total charge-transfer cross sections for the ${\mathrm{H}}_2^{+}$-rare-gas systems.