2 research outputs found
Correlating Droplet Size with Temperature Changes in Electrospray Source by Optical Methods
We investigated how the temperature
and size of charged droplets
are affected by the electrospray ionization (ESI) process, using <i>in situ</i> measurements involving laser-induced fluorescence
and Mie scattering on a thermal gradient focusing ESI source. Rhodamine
dyes were employed as temperature indicators using ratiometric intensity-based
fluorescence techniques. The results were compared to lifetime-based
techniques using tris(2,2′-bipyridyl)dichlororuthenium(II)
hexahydrate, [Ru(bpy)<sub>3</sub>]<sup>2+</sup>. Both methods gave
similar profiles. Nevertheless, the precision and sensitivity were
higher for lifetime-based techniques in comparison to intensity-based
techniques. Global warming (with Δ<i>T</i> ∼10
K) of the ESI plume is reported while the size of the droplet decreases
along the plume. The global warming indicates that the conductive
thermal transfer (between the superheated sheath gas and the solvent)
is predominant and stronger than the cooling effect due to the evaporation
of the droplets, and this outcome is effectively reproduced by a diffusion-controlled
evaporation model. Thermal gradient focusing ESI sources therefore
appear to be efficient sources for evaporating large amounts of solvent,
along with an increase in temperature
Temperature Response of Rhodamine B‑Doped Latex Particles. From Solution to Single Particles
Nanoparticle-based
temperature imaging is an emerging field of
advanced applications. Herein, the sensitivity of the fluorescence
of rhodamine B-doped latex nanoparticles toward temperature is described.
Submicrometer size latex particles were prepared by a surfactant-free
emulsion polymerization method that allowed a simple and inexpensive
way to incorporate rhodamine B into the nanoparticles. Also, rhodamine
B-coated latex nanoparticles dispersed in water were prepared in order
to address the effect of the dye location in the nanoparticles on
their temperature dependence. A better linearity of the temperature
dependence emission of the rhodamine B-embedded latex particles, as
compared to that of free rhodamine B dyes or rhodamine B-coated latex
particles, is observed. Temperature-dependent fluorescence measurements
by fluorescent confocal microscopy on individual rhodamine B-embedded
latex particles were found similar to those obtained for fluorescent
latex nanoparticles in solution, indicating that these nanoparticles
could be good candidates to probe thermal processes as nanothermometers