Charge profiles of thin electret films mapped with subnanosecond thermal pulses

Charge profiles in various electret films are mapped with a resolution of 7 nm, using thermal pulses generated by the absorption of picosecond excimer-laser pulses. The use of these films for calorimetry and thermometry of radiation-induced transient heating with a time resolution of 350 psec is demonstrated, and applications for their use as ultrafast detectors for ultrasound are discussed.