Enantio-specific Detection of Chiral Nano-Samples Using Photo-induced Force

TL;DR

This paper introduces a high-resolution microscopy technique that detects chiral nanoscale samples by measuring differential photo-induced forces, enabling enantio-specific identification based on optical force analysis.

Contribution

The study presents a novel analytical framework for enantio-specific detection using photo-induced forces, with numerical validation and insights into sensitivity enhancement.

Findings

Differential force is linked to enantiomer type.

Force depends linearly on chiral and electric responses.

Method detects nanoscale chiral samples with chirality ~0.01.

Abstract

We propose a novel high resolution microscopy technique for enantio-specific detection of chiral samples down to sub-100 nm size, based on force measurement. We delve into the differential photo-induced optical force exerted on an achiral probe in the vicinity of a chiral sample, when left and right circularly polarized beams separately excite the sample-probe interactive system. We analytically prove that the differential force is entangled with the enantiomer type of the sample enabling enantio-specific detection of chiral inclusions. Moreover, we demonstrate that the differential force is linearly dependent on both the chiral response of the sample and the electric response of the tip and is inversely related to the quartic power of probe-sample distance. We provide physical insight into the transfer of optical activity from the chiral sample to the achiral tip based on a rigorous analytical approach. We support our theoretical achievements by several numerical examples, highlighting the potential application of the derived analytic properties. Lastly, we demonstrate the sensitivity of our method to enantio-specify nanoscale chiral samples with chirality parameter in the order of 0.01, and discuss how this could be further improved.