Crosslinked polymeric materials are described that contain pendant amine capture groups. The polishing pad includes a substrate, and the substrate includes a polishing surface and a reverse surface corresponding to the polishing surface. Further, methods to inspect primary electron beams, to adjust final focus lengths and to calibrate the multiple electron beam device are provided. The plurality of inputoutput units receive a positive and a negative control signals and generate a first superimposed current at the first differential output pair.