Evidence of Different Charging Behavior of Conductive and Dielectric Materials in Low-Temperature Plasmas and a New Diagnostic for Low-Energy Electron Absorption.

In any physical system where a surface is hit by electrons, the sticking probability s of the electrons is a central parameter governing, for example, the charging of the surface. For dielectrics, it could previously only be measured for high energies (>100  eV), while it is well-known for metals even at energies of only a few eV. Recent theoretical investigations concerning dielectrics such as silica predict values for s significantly below 1.

Charge measurement of SiO_{2} nanoparticles in an rf plasma by ir absorption.

We have performed measurements of the ir absorption of SiO_{2} nanoparticles confined in an argon radiofrequency plasma discharge using a Fourier transform infrared spectrometer. By varying the gas pressure of the discharge and duty cycle of the applied radiofrequency voltage, we observed a shift of the absorption peak of SiO_{2}. We attributed this shift to charge-dependent absorption features of SiO_{2}.