Nonphotochemical Laser-Induced Nucleation of Potassium Halides: Effects of Wavelength and Temperature

Martin R. Ward, Andrew J. Alexander, Andrew Alexander

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

Nonphotochemical laser-induced nucleation (NPLIN) of KCl and KBr has been studied using nanosecond laser pulses with wavelengths of 532 and 1064 nm. The ratio of the number of samples nucleated to the number irradiated with the laser (f) follows a nonlinear dependence on peak power density that approaches f = 1 at higher incident powers, which we fit with a Poisson function. The threshold power required to nucleate samples is lower at 532 than at 1064 nm, and we observe that a higher fraction of samples nucleate when exposed to 532 nm pulses at a given laser power. In comparison to KCl, we see higher fractions of KBr samples nucleate and lower threshold values at both wavelengths. Samples of KCl of equal supersaturation at two different temperatures (23 and 33 degrees C) shot with 1064 nm pulses show that the 33 degrees C samples are significantly more labile to nucleation. The ratio of samples nucleated at 33 degrees C compared to those at 23 degrees C was 2.11 +/- 0.47. A classical nucleation model based on activation of subcritical clusters in solution accounts remarkably well for the experimental data and provides phenomenological values of the crystalsolution-interfacial tension (gamma) at 23 degrees C for KCl and KBr of 5.283 and 4.817 mJ m(-2). At 33 degrees C, the model yields a best-fit value of gamma = 5.429 mJ m(-2) for KCl.

Original languageEnglish
Pages (from-to)4554-4561
Number of pages8
JournalCrystal Growth and Design
Volume12
Issue number9
DOIs
Publication statusPublished - 5 Sept 2012

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