Complex sentence: The Plasmon resonant frequency is highly sensitive to the refractive index of the environment "The change in refractive index results in a shift in the resonant frequency", as the resonant frequency is easy to measure, this allows LSP nanoparticles to for nanoscale sensing applications.
Split into simpler sentences: The plasmon resonant frequency is highly sensitive to the refractive index of the environment; a change in refractive index results in a shift in the resonant frequency. As the resonant frequency is easy to measure, this allows LSP nanoparticles to be used for nanoscale sensing applications.