An improved device, method, and system efficiently couple high-frequency energy from radiation-assisted field emission. Definable charge labels couple with the particles to form charge-modified particles which display with a different migratory behavior in FFE The apparatus includes focusing buffers between the separation medium and at least one electrode which has much higher electrical conductivity than the separation medium. In transmitting the document data, it is determined whether to transmit the document data after the data at the link destination is embedded in it.