(469h) Nonphotochemical Laser-Induced Nucleation of KCl Aqueous Solution in Microfluidics

It was reported for the first time in 1996 by Garetz et al. that homogeneous nucleation was induced when supersaturated urea solution was exposed to intense laser pulses¹. Since then, the same phenomenon has been observed in numerous systems, namely alkali halide^2–4, glycine⁵, and proteins⁶. In the present work, we designed and fabricated a microfluidic device, which enables continuous-flow laser-induced nucleation and real-time in situ characterization. Supersaturated condition being achieved via on-chip thermoelectrical cooling significantly simplified the experimental procedure and minimized the risk of contamination. We examined the influences of flow rate, laser power density, laser exposure, and supersaturation. The threshold laser power densities and nucleation labilities observed in our experiments agreed well with those reported by Alexander et al. using static cells⁷. An increase in the supersaturation resulted in an increase in the mean crystal size found downstream from the nucleation zone. An increasing supersaturation and laser power density caused an increasing number of the crystals nucleated. However, the number of laser pulses was found to have no effect on number of crystals nucleated. These results are consistent with the dielectric polarization model of Alexander et al.⁸.

References:

(1) Garetz, B. A.; Aber, J. E.; Goddard, N. L.; Young, R. G.; Myerson, A. S. Phys. Rev. Lett. 1996, 77 (16), 3475–3476.

(2) Fang, K.; Arnold, S.; Garetz, B. A. Cryst. Growth Des. 2014, 14 (5), 2685–2688.

(3) Ward, M. R.; Alexander, A. J. Cryst. Growth Des. 2012, 12 (9), 4554–4561.

(4) Ward, M. R.; Rae, A.; Alexander, A. J. Cryst. Growth Des. 2015, 15 (9), 4600–4605.

(5) Zaccaro, J.; Matic, J.; Myerson, A. S.; Garetz, B. A. Cryst. Growth Des. 2001, 1 (1), 5–8.

(6) Lee, I. S.; Evans, J. M. B.; Erdemir, D.; Lee, A. Y.; Garetz, B. A.; Myerson, A. S. Cryst. Growth Des. 2008, 8 (12), 4255–4261.

(7) Alexander, A. J.; Camp, P. J. Cryst. Growth Des. 2009, 9 (2), 958–963.

(8) Alexander, A. J.; Camp, P. J. J. Chem. Phys. 2019, 150 (4), 040901.