Sound emission from the gas of molecular superrotors

TL;DR

This study demonstrates that laser-induced molecular superrotation generates audible sound waves through energy transfer, with sound amplitude directly proportional to the rotational energy imparted, opening new avenues for photo-acoustic applications.

Contribution

First experimental analysis linking molecular superrotation energy to sound emission, confirming rotational excitation as the primary source of the acoustic signal.

Findings

Sound amplitude correlates with rotational energy

Rotational excitation causes localized gas heating and sound generation

Potential for photo-acoustic control and spectroscopy

Abstract

We use an optical centrifuge to deposit a controllable amount of rotational energy into dense molecular ensembles. Subsequent rotation-translation energy transfer, mediated by thermal collisions, results in the localized heating of the gas and generates strong sound wave, clearly audible to the unaided ear. For the first time, the amplitude of the sound signal is analyzed as a function of the experimentally measured rotational energy. The proportionality between the two experimental observables confirms that rotational excitation is the main source of the detected sound wave. As virtually all molecules, including the main constituents of the atmosphere, are amenable to laser spinning by the centrifuge, we anticipate this work to stimulate further development in the area of photo-acoustic control and spectroscopy.