Year: 2026
Type: article
Abstract: Aqueous microdroplets have fascinated scientists with unique properties that deviate from bulk solutions. Understanding microdroplet chemistry has been limited by few spectroscopic measurements on single well-defined microdroplets. Here we present a new technique to record an IR spectrum of a single droplet called Single Droplet Displacement Infrared Action Spectroscopy (SiDDIRAS) with potential broad applications in physical, analytical, and environmental chemistry. The droplet was trapped in a linear quadrupole electrodynamic balance. When IR radiation at resonant frequency was introduced, mass loss from IR-induced evaporation caused the droplet to displace upwards. Mapping the displacement as a function of IR frequency yields an IR spectrum of a single microdroplet. As a demonstration, the SiDDIRA spectrum of an ~8 µm droplet containing NaCl and NaN3 shows that the azide asymmetric stretch blueshifts by 5 cm-1 relative to bulk with significant peak broadening, evidence that this droplet is supersaturated with salts compared to bulk solutions. Single Droplet Displacement IR Action Spectroscopy is a new technique to obtain IR spectra of substrate-free single droplets held in an electrodynamic balance by mapping the droplet’s IR-induced displacement as a function of IR frequency.
Source: Nature Communications
Authors: Thien Khuu, Mythreyi Rayaluru, Brandon Young, Prakriti Singh, Aaron M. Palmisano, Ryan D. Davis, James F. Davies, Jahan M. Dawlaty
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $6,990
Awards: G1152772959, G11630931, G14018713, G1523888516, G1536208995, G1699268964, G2214935549, G2308559942, G3232274386, G3438499258, G413247060, G4516736450, Postdoctoral Fellowship: MPS-Ascend: Quantifying Accelerated Reaction Kinetics in Microdroplets with pH-Jump and Mass Spectrometry: From Small Molecules to Proteins and Beyond, G4771968897, G4903105778, CAS-Climate: Basicity in the Excited State and under Interfacial Confinement: Fundamentals and Applications to Catalysis, G5339743583, G5556147165, G6338696783, G7498346495, G855168022
OpenAlex ID: W7140605460