SCHAEBERLE, BECKER AND THE COOLING EARTH

Intrinsic Evaporative Cooling by Hygroscopic Earth Materials

The phase change of water from liquid to vapor is one of the most energy-intensive physical processes in nature, giving it immense potential for cooling. Diverse evaporative cooling strategies have resulted worldwide, including roof ponds and sprinklers, courtyard fountains, wind catchers with qanats, irrigated green roofs, and fan-assisted evaporative coolers. These methods all require water i...

Feasibility of Cooling and Trapping Metastable Alkaline-Earth Atoms

Metastability and long-range interactions of Mg, Ca, and Sr in the lowest-energy metastable P2 state are investigated. The calculated lifetimes are 38 min for Mg , 118 min for Ca , and 17 min for Sr , supporting feasibility of cooling and trapping experiments. The quadrupole-quadrupole long-range interactions of two metastable atoms are evaluated for various molecular symmetries. Hund’s case (c...

Enhanced laser cooling of rare-earth-ion-doped nanocrystalline powders

The enhanced laser cooling performance of rare-earth-ion-doped nanocrystalline powders is predicted, compared to the bulk material, using Yb:Y2O3 as the model material. This is achieved by enhancing the off-resonance, phonon-assisted absorption, which is proportional to the three factors considered in this paper: the dopant concentration, the pumping field energy, and the excitation coefficient...

Proposal for laser-cooling of rare-earth ions

Single-stage sub-Doppler cooling of alkaline earth atoms.

We report the first experimental study of sub-Doppler cooling in alkaline earth atoms (87Sr) enabled by the presence of nuclear spin-originated magnetic degeneracy in the atomic ground state. Sub-Doppler cooling in a sigma(+)-sigma(-) configuration is achieved despite the presence of multiple, closely spaced excited states. This surprising result is confirmed by an expanded multilevel theory of...