SINGLE MOLECULE CHIRAL ANALYTICS

With support from the Chemical Measurement and Imaging Program in the Division of Chemistry, Professor David Patterson of the University of California, Santa Barbara will develop tools capable of identifying the exact structure of a single, trapped molecule. This includes not only determining the molecule’s chemical formula but also its handedness (chirality). Many molecules, including most found in biological systems, exist in left- and right-handed forms, much like left- and right-handed gloves. This chirality plays a critical role in molecular function, yet it remains difficult to measure using existing analytical techniques. A successful tool could have broad applications in biology and chemistry and may help illuminate the origins of homochirality in life on Earth. Students working on these next-generation techniques will form the backbone of tomorrow’s technological workforce. Chirality will be detected in a single molecule through a non-destructive, multi-step process. First, the target molecule will be co-trapped with a laser-coolable atom, which can be imaged via laser-induced fluorescence. The ensemble will be cooled to a few Kelvin through collisions with cold helium gas. At this temperature, carefully tailored microwave pulses will manipulate the molecule’s rotational state. A specific combination of three resonant pulses, polarized along the x, y, and z axes, will be chosen to selectively excite one enantiomer while leaving the other unaltered. The resulting rotational state will then be read out using inelastic recoil spectroscopy, a recently demonstrated, non-destructive method capable of measuring the rotational and vibrational state of a single molecule. The molecule is then re-cooled, and the process repeated many times to achieve high-fidelity measurement. Similar spectroscopic techniques will be employed to determine the molecule’s isomer and isotopomer. Prior to this work, measuring both the identity and chirality of a single molecule has remained well beyond the state of the art. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.