Molecular Beam Electric Field Deflection: Experimental Considerations

Scaling of the permanent electric dipole moment in isolated silicon clusters with near-spherical shape

“…1 is the value of the polarizability per atom of 3.71 Å 3 expected for a small sphere with the dielectric properties of bulk α-Si according to the Clausius–Mossotti relationship. 5,7 It can be seen that the effective polarizabilities of the smallest here investigated clusters with 30 atoms are similar to those expected for a small sphere with the bulk properties of α-Si within the limits of measurement accuracy. Thus, the dipolar contribution plays almost no role here.…”

“…these clusters are floppy and the electric dipole moment is completely quenched. 5 In total, two series of measurements are presented that were performed with different helium valve opening times and hence at different cluster generation conditions. Due to this changed setting, the cluster velocities are different in both measurements, although the nozzle temperatures were the same.…”

“…From the deflection of the clusters by an inhomogeneous electric field, the polarizability α was determined and converted into the dielectric constant with the help of the Clausius–Mossotti relationship. 5 In a more recent work, 6 this effect could not be confirmed, since the values for the polarizabilities were found to agree well with those of a small polarizable sphere with the dielectric properties of bulk α-Si. 7 However, the experiments were performed on thermally excited clusters, for which a possible dipolar contribution is almost completely quenched and therefore hardly observable.…”