Observation of a phase transition in an electrodynamically levitated NH4NO3 microparticle by Mie and Raman scattering

Abstract

The observation of a phase transition from a solid microparticle into a liquid droplet of a single levitated NH 4 NO 3 particle using an electrodynamic balance for particle levitation combined with Raman and Mie spectrospcopy is reported. The phase transition from the solid to the dissolved NH 4 NO 3 can be followed by characteristic changes in the spectral location of Raman signals and by a characteristic decrease in the refractive index and an increase in the particle radius, which is deduced from Mie scattering data. Copyright

Investigation of the hygroscopic properties of Ca(NO<sub>3</sub>)<sub>2</sub> and internally mixed Ca(NO<sub>3</sub>)<sub>2</sub>/CaCO<sub>3</sub> particles by micro-Raman spectrometry

“…Micro-Raman spectroscopy allows in situ analyses of the dynamic processes of micro-sized individual aerosol particles and has unexplored potential in characterizing aerosol hygroscopic behavior. The concentration dependence of spontaneous Raman scattering allows the quantitative analysis of the water content of liquid droplets (Reid et al, 2007), at the same time, peak position of the anion Raman band is a sensitive indicator of the chemical structure of particles and hence phase transition (Widmann et al, 1998;Musick et al, 2000). Moreover, morphological changes can also be observed with microscope equipped to Raman spectrometer.…”

Understanding hygroscopic growth and phase transformation of aerosols using single particle Raman spectroscopy in an electrodynamic balance

“…Raman peaks are relatively small, within a few wavenumbers only. 21,34 Hence, we did not use the peak shifts for the phase transformation analysis in our study.…”

Origin of salt mixtures and mixed salts in atmospheric particulate matter

“…Individual particles may be analyzed by Raman spectroscopy; several investigations of this kind have been reported showing the suitability of this technique for chemical characterization of atmospheric particles. [22][23][24][25][26][27][28][29] In this contribution, we postulate the possible generation of atmospheric particles as mixtures of salts and/or mixed salts based on the fundamental role of water. When Raman spectroscopy is used as an analytical technique, the assignment and interpretation of the Raman signals is crucial.…”

“…Individual particles may be analyzed by Raman spectroscopy; several investigations of this kind have been reported showing the suitability of this technique for chemical characterization of atmospheric particles …”