Coherent Enantiomer-Selective Population Enrichment Using Tailored Microwave Fields.

We report the experimental demonstration of coherent enantiomer-selective enrichment of chiral molecules by employing a novel microwave five-pulse scheme. Our results show that enantiomers can be selectively transferred to a rotational level of choice by applying sequences of resonant microwave pulses in a phase- and polarization-controlled manner. This is achieved by simultaneously exciting all three kinds of electric dipole-allowed rotational transitions and monitoring the effect on a fourth rotational transition of choice. Using molecular beams, we apply our method to two chiral terpenes and obtain a 6 % enantiomeric enrichment, which is one order of magnitude larger than that recently reported in a buffer-gas cell experiment. This approach establishes a robust scheme for controlled manipulation of enantiomers using tailored microwave fields and opens up new avenues for chiral purification and enrichment that can be used in a broad scope of analytical or spectroscopic applications.