Towards redistribution laser cooling of molecular gases: production of candidtate molecules SrH by laser ablation

Abstract

Laser cooling by collisional redistribution of radiation has been successfully applied in the past for cooling dense atomic gases. Here we report on progress of work aiming at the demonstration of redistribution laser cooling in a molecular gas. The candidate molecule strontium monohydride is produced by laser ablation of strontium dihydride in a pressurized noble gas atmosphere. The composition of the ablation plasma plume is analyzed by measuring its emission spectrum. The dynamics of SrH molecular density following the ablation laser pulse is studied as a function of the buffer gas pressure and the laser intensity.

Theoretical Investigation of Spectroscopic Properties of the Alkaline-Earth-Metal Monohydrides toward Laser Cooling and Magneto-Optical Trapping

“…Recently, BaH has been extensively examined by Zelevinsky et al both theoretically via ab initio calculations and experimentally via spectroscopic detection and direct laser cooling. − They obtained vibrational branching ratios for B 2 Σ + – X 2 Σ + and A 2 Π 1/2 – X 2 Σ + optical cycling transitions using fluorescence and absorption detection, confirming the A 2 Π 1/2 state as a superior choice for laser cooling rather than the B 2 Σ + state, based on which Zelevinsky et al adopted A 2 Π 1/2 ← X 2 Σ + as the optical cycling transition while repumping excited vibrational levels of the ground state through the B 2 Σ + state. Some research groups are also considering CaH ,, and SrH as candidates for laser cooling. In general, AEMHs have been analyzed theoretically using the ab initio quantitative method to build their potential energy curves, vibrational transitions, and FCFs; ,, however, a systematic spectroscopic evaluation of AEMHs toward laser cooling and magneto-optical trapping is still missing.…”

Laser cooling of dense atomic gases by collisional redistribution of radiation and spectroscopy of molecular dimers in a dense buffer gas environment

“…Also, we present initial spectroscopic experiments on an alkali-dimer -noble gas mixture which constitutes a promising candidate for redistributional laser cooling of molecules, following an alternative approach for the production of suitable molecules instead of laser ablation. 13 Our experiments are carried out using hot alkali atoms vapor in a noble gas environment under high pressure (up to 230 bar). In this regime, the alkali resonances become strongly broadened so that their linewidth is of the order of the thermal energy k B T in frequency units.…”