Do thermal effects cause the propulsion of bulk graphene material?

Wu, Lei and Zhang, Yonghao and Lei, Yian and Reese, Jason M. (2016) Do thermal effects cause the propulsion of bulk graphene material? Nature Photonics, 10 (3). p. 139. ISSN 1749-4885

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    Abstract

    In a recent article, Zhang et al.1 observed the direct propulsion of a bulk graphene sponge when exposed to laser light. They attributed this to the momentum of the light-induced ejected electrons. However, the force provided by the ejected electrons is about 2.7 × 10−11 N (supposing that the average current and the kinetic energy of the ejected electrons are 9 × 10−7 A and 70 eV, respectively), which is far smaller than the gravitational force of a 0.86 mg graphene sponge. From our knowledge of rarefied gas dynamics, the horizontal, vertical and rotational motion of the laser-illuminated graphene sponge could be due to the radiometric force.