Figure 18.2 — Coagulation of optically trapped aerosol droplets Fig. 18.2 — Coagulation of optically trapped aerosol droplets. Simultaneous manipulation, coagulation and spectroscopic sizing of optically trapped aqueous aerosol droplets. Two droplets in separate holographic optical tweezers are brought together until they fuse. Evident in the CERS spectrum are the WGMs of the two droplets, identified with circles or crosses in spectra (a) and (b), and the modes of the final coagulated droplet in part (c).Reprinted from Buajarern et al., J. Chem. Phys. 125, 114506. Copyright (2006) American Institute of Physics.