Transmission of low energy electrons through a polyethylene terephthalate 800-nm diameter nanocapillary

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The transmission of 2-keV electrons through a polyethylene terephthalate (PET) nanocapillary with a diameter of 800 nm and a length of 10 μm is studied. The transmitted electrons are detected using microchannel plate (MCP) with a phosphor screen. It is found that the transmission rate for the transmitted electrons with the incident energy can reach up to 10 % for an aligned capillary in the beam direction, but drops to less than 1% when the tilt angle exceeds the geometrical allowable angle. The transmitted electrons with the incident energy do not move with change of tilt angle, so the incident electrons are not guided in the insulating capillary, which is different from the scenario of positive ions. In the final stage of the transmission, the angular distribution of the transmitted electrons within the geometrical allowable angle splits into two peaks along the observation angle perpendicular to the tilt angle. The time evolution of the transmitted full angular distribution shows that when the beam turns on, the transmission profile forms a single peak. As the incident charge and time accumulate, the transmission profile starts to stretch in the plane perpendicular to the tilt angle and gradually splits into two peaks. When the tilt angle of the nanocapillary exceeds the geometrical allowable angle, this splitting tends to disappear. Simulation of the charge deposition in the capillary directly exposed to the beam indicates the formation of positive charge patches, which are not conducive to guidance, as seen in the case of positive ions. According to the simulation results, we can explain our data. Then, the possible reasons for the splitting the transmission angular profiles are discussed.