Mid-Infrared Optical Force Chromatography of Microspheres Containing Siloxane Bonds
Darmawan, YA (Darmawan, Yoshua Albert); Goto, T (Goto, Takuma); Yanagishima, T (Yanagishima, Taiki); Fuji, T (Fuji, Takao); Kudo, T (Kudo, Tetsuhiro)
Journal of Physical Chemistry Letters, 2023, Volume 14, pp. 7306-7312.
Recent interest in particle sorting using optical forceshas growndue to its ability to separate micro- and nanomaterials based on theiroptical properties. Here, we present a mid-infrared optical forcemanipulation technique that enables precise sorting of microspheresbased on their molecular vibrational properties using a mid-infraredquantum cascade laser. Utilizing the optical pushing force drivenby a 9.3 & mu;m mid-infrared evanescent field generated on a prismthrough total internal reflection, a variety of microspheres, includingthose composed of Si-O-Si bonds, can be separated inaccordance with their absorbance values at 9.3 & mu;m. The experimentalresults are in good agreement with the optical force calculationsusing finite-difference time-domain simulation. Thus, each microsphere'sdisplacement and velocity can be predicted from the absorbance value;conversely, the optical properties (e.g., absorbance and complex refractiveindex in the mid-infrared region) of individual microspheres can beestimated by monitoring their velocity. |
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