XPS depth profiling of polystyrene etched by electrospray droplet impact

The molecular‐level depth profiling of polystyrene (PS) has been performed by using a newly designed electrospray droplet impact (EDI) gun. The multiple charged water droplets with kinetic energy of ∼10 6 eV were irradiated to a bulk and a spin‐coated PS. When a PS target is etched by EDI, the ablation of the sample is suppressed to minimal, i.e. the shallow surface etching with nonrecognizable damage on the surface is realized. It was found that XPS spectra for PS were independent on the irradiation time by EDI. This indicates that EDI is a unique technique for the surface etching of synthetic polymer materials without resulting in any damage to the etched surface.