A device configured to convert or amplify a particle, the conversion or amplification being reliant on the impact of a particle on a surface of the device causing emission of one or more secondary electrons from the same surface. The device includes a carbon-based layer capable of secondary electron emission upon impact of a particle. The surface may be used to convert, for example, an ion into an electron signal, or an electron signal into an amplified electron signal, such as in conversion or amplification dynodes.