2015/06/09 by A. Milner, A. A. Milner, Aleksey Korobenko +4 · 26 citations
Physics and Astronomy · #Advanced Fiber Laser Technologies #Angular momentum #Anisotropy #Atomic and Molecular Physics #Atomic physics #Birefringence #Classical mechanics #Computational physics #Excitation #Isotropy #Laser-Matter Interactions and Applications #Materials science #Optical tweezers #Optics #Physics #Rotation (mathematics) #Rotation around a fixed axis #Rotational energy #Rotational transition #Thermal #Thermal equilibrium #Thermodynamics #physics.optics
paper · pdf · doi:10.1103/physrevx.5.031041
published in Physical Review X 5(3) (American Physical Society)
arxiv created 2015/06/09 · openalex publication_date 2015/09/23 · arxiv updated 2015/09/30 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Localized heating of a gas by intense laser pulses leads to interesting acoustic, hydrodynamic, and optical effects with numerous applications in science and technology, including controlled wave guiding and remote atmosphere sensing. Rotational excitation of molecules can serve as the energy source for raising the gas temperature. Here, we study the dynamics of energy transfer from the molecular rotation to heat. By optically imaging a cloud of molecular superrotors, created with an optical centrifuge, we experimentally identify two separate and qualitatively different stages of its evolution. The first nonequilibrium "gyroscopic" stage is characterized by the modified optical properties of the centrifuged gas-its refractive index and optical birefringence, owing to the ultrafast directional molecular rotation, which survives tens of collisions. The loss of rotational directionality is found to overlap with the release of rotational energy to heat, which triggers the second stage of thermal expansion. The crossover between anisotropic rotational and isotropic thermal regimes is in agreement with recent theoretical predictions and our hydrodynamic calculations.