Energy-loss scaling in 0.5-3.5-keV ${\mathrm{Ne}}^{+}$ and Ne collisions with ${\mathrm{H}}_2$ and ${\mathrm{D}}_2$

Energy losses are measured in ${\mathrm{Ne}}^{+}$ +${\mathrm{D}}_2$, ${\mathrm{Ne}}^{+}$ +${\mathrm{H}}_2$, and Ne + ${\mathrm{D}}_2$ collisions for beam energies $0.5\le E\le 3.5$ keV and scattering angles $\theta \le 5$ deg. Rotational and vibrational excitation of the target molecule is found, but the probability of direct electronic excitation is seen to be extremely small. The results indicate that the most probable laboratory energy loss $T_0$ for a projectile with mass $M_p$ scattered by a homonuclear binary molecule with atomic masses $M$ scales so that the quantity $f=\frac{T_{0}M}{\left(M_{p}E{\theta }^2\right)}$ is a function of the reduced scattering angle $\tau =E\theta$ only, as recently predicted theoretically by Sigmund. The function $f\left(\tau \right)$ is found to be the same for the ${\mathrm{Ne}}^{+}$ + ${\mathrm{D}}_2$ and ${\mathrm{Ne}}^{+}$ + ${\mathrm{H}}_2$ systems, but is strongly dependent on the charge state of the projectile.