A Scheme for Ultrasensitive Detection of Molecules by Using Vibrational Spectroscopy in Combination with Signal Processing

TL;DR

This paper presents a novel method combining vibrational spectroscopy and signal processing, specifically matched filtering, to detect molecules with ultrasensitivity even in high-noise conditions, demonstrated on nerve agent molecules.

Contribution

It introduces a new detection scheme that enhances sensitivity by applying matched filters to vibrational spectra, accounting for spectral range and anharmonicity effects.

Findings

Detection possible at SNR as low as 0.1

Full spectral range improves detection over narrow windows

Accounting for anharmonicity enhances detection accuracy

Abstract

We show that combining vibrational spectroscopy with signal processing can result in a scheme for ultrasensitive detection of molecules. We consider the vibrational spectrum as a signal on the energy axis and apply a matched filter on that axis. On the example of a nerve agent molecule, we show that this allows detecting a molecule by its vibrational spectrum even when the recorded spectrum is completely buried in noise, when conventional spectroscopic detection is impossible. Detection is predicted to be possible with signal-to-noise ratios in recorded spectra as low as 0.1. We study the importance of spectral range used for detection as well as of the quality of the computed spectrum used to program the filter, specifically, the role of anharmonicity, of the exchange correlation functional, and of the basis set. The use of the full spectral range rather than of a narrow spectral window with key vibrations is shown to be advantageous, as well as accounting for anharmonicity.