Chemical analysis from a distance: Spatially resolved, remote sensing using backward transient absorption

• Multi-component trace chemicals remote sensing using the backward transient absorption spectroscopy. • Identified three chemically similar, tertiary amines from a distance: trimethylamine, N, N-dimethylethanamine, and N, N-dimethylisopropylamine. • Simultaneous measurement of the excited-state lifetime and the spatial vapor distribution of target chemicals. The lifetimes can act as an additional identifier of the molecules. • Achieved a spatial resolution in the sub-millimeter range, limited by the duration of the laser pulses and the signal to noise level. Identification of chemical species from a distance is achieved with backward transient absorption spectroscopy. The experiments employ UV excitation followed by a Rydberg-Rydberg transition that gives the method its inherent molecule-specificity. Using three similar amines, we demonstrate that backward transient absorption spectroscopy can identify closely related compounds. The distance of the vapors is measured independently with a sub-millimeter spatial resolution, limited by the duration of the laser pulses and the signal level. The combination of high sensitivity and excellent spatial resolution makes backward transient absorption spectroscopy an excellent choice for applications where chemical structures can be identified from a distance.