Sodium doped binary clusters I: Ionization potentials of SinNam clusters

Sodium doped silicon clusters (Si_nNa_m, 3n11, 1m4) were produced by two independent laser vaporization methods and their ionization potentials were measured by scanning the wavelength of the UV dye laser. The IPs of most Si_nNa_m clusters decrease monotonously with the number of Na atoms, but IPs of Si₇Na_m and Si₁₀Na_m clusters show an apparent even-odd alternation; odd numbers of Na atoms efficiently decrease the IP but even numbers of Na atoms never significantly decrease the IPs. In addition, the reactivity of Si_nNa_m clusters for NO molecules was investigated with a fast flow reactor, and an anti-correlation between IP and the reactivity was clearly observed; clusters having high IP show low reactivity andvice versa.