Ultrasonic studies of perfluoro-n-alkanes

Abstract

Measurements of the ultrasonic relaxation in perfluoro-n-pentane and perfluoro-n-hexane are reported. The relaxation is ascribed to rotational conformational changes which have an activation energy of 9.2 ± 5 kJ mol^–1 which is surprisingly similar to that observed in the analogous normal alkanes. A marked feature of the acoustic absorption is its unusually large high frequency limiting value which is ascribed to thermal losses associated with the low sound propagation velocity.