Voltage effects on the nanoelectrospray characteristics in fully voltage-controlled atomisation of gold nanocolloids

The voltage effects on fully voltage-controlled nanoelectrospraying of aqueous gold nanocolloids were investigated. In the nanoelectrospray using 30 μm nozzle, with an increasing of voltage two stable spray regimes of pulsating and cone-jet mode were clearly observed by a combination of current measurement and fast imaging technology. In this nanoelectrospray uniquely determined by the electrical field voltage the current-voltage characteristics were analysed and evaluated based on an equivalent circuit method. At high field in cone-jet regime all the equivalent resistances derived by fitting appear close to a value of 0.53 ± 0.03 GΩ, showing independence to the conductivity of the nanocolloids. In low field pulsating regime a high pulsation frequency up to 100 kHz with relatively stable current pulse was exhibited in all the gold nanocolloids. A linear relationship between the DC components in the pulsating current and the voltage was found and the DC equivalent resistance obtained from the fitting varies between 0.90 and 1.47 GΩ. A strong correlation between the pulsating properties and the conductivity of the colloids was identified.