Study of condensational growth of water droplets by Mie resonance spectroscopy

An optical technique using MIE resonance scattering spectroscopy to monitor the growth of a saline solution droplet is presented. This technique utilizes a quadrupole particle trap to suspend a charged NaCl solution droplet in a water vapor environment and a CO(2) laser to momentarily perturb the droplet-vapor equilibrium. The condensational growth of this droplet is monitored by means of multiple Mie resonances observed at right angle scattering. A least-squares fit, used to evaluate the condensation coefficient of water, shows that the value tends to approach unity. In addition, this new approach reduces the error in dry salt size measurement to <1%.