Arrays of Magnetic Nanoparticles Patterned via “Dip‐Pen” Nanolithography

Oxygen saturated, dilute benzene solutions (corresponding to ca. 1 mM monomer units) of the polymers shown in Figure 1 were contained in a microwave cell of internal dimensions 3.5 ” 7.1 ” 24 mm. The solutions were irradiated with 5 or 10 ns pulses of 3 MeV electrons from a Van de Graaff accelerator with a total absorbed dose per pulse, D, of approximately 1 ” 10 J/m which was accurately measured for each experiment. This resulted initially in the formation of a uniform concentration of ca. 0.1 lM of excess electrons and benzene radical cations. The resulting change in the conductivity of the solution was measured as the change in the power of microwaves (26±38 GHz) reflected by the cell. Using only a single pulse the radiation-induced conductivity could be monitored from 10 ns to 1 ms using a pseudo-logarithmic time-base. The experimental methodology and data reduction procedures have been described in detail previously [4,5].