Complex sentence: A microprobe is an instrument that applies a stable and well-focused beam of charged particles (electrons or ions) used to determine the chemical composition of solid materials (minerals, glasses, metals).
Split into simpler sentences: A microprobe is an instrument that applies a stable and well-focused beam of charged particles (electrons or ions) to a sample. Scientists use this beam of charged particles to determine the elemental composition of solid materials (minerals, glasses, metals).