Simple all-optical method for in situ detection of ultralow amounts of ammonia

TL;DR

This paper introduces a novel, non-contact optical method capable of detecting extremely low levels of ammonia molecules rapidly and with high spatial resolution, suitable for environmental and industrial applications.

Contribution

The paper presents a simple, affordable all-optical technique for in situ detection of ultralow ammonia levels using surface-enhanced Raman signals, enabling high-resolution spatial observations.

Findings

Detection of only a few thousand ammonia molecules.

High spatial resolution in ammonia detection.

Rapid, nonperturbative in situ measurement.

Abstract

As a key precursor for nitrogenous compounds and fertilizer, ammonia affects our lives in numerous ways. Rapid and sensitive detection of ammonia is essential, both in environmental monitoring and in process control for industrial production. Here we report a novel and nonperturbative method that allows rapid detection of ammonia at detection levels of only a few thousand molecules, based on the non-contact, all-optical detection of surface-enhanced Raman signals. We show that this simple and affordable approach enables ammonia probing at selected regions of interest with high spatial resolution, making in situ and operando observations possible.