 |
| Titel |
Probing ice-nucleation processes on the molecular level using second harmonic generation spectroscopy |
| VerfasserIn |
A. Abdelmonem, J. Lützenkirchen, T. Leisner |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1867-1381
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 8, no. 8 ; Nr. 8, no. 8 (2015-08-27), S.3519-3526 |
| Datensatznummer |
250116546
|
| Publikation (Nr.) |
 copernicus.org/amt-8-3519-2015.pdf |
|
|
|
|
|
| Zusammenfassung |
| We present and characterize a novel setup to apply second harmonic
generation (SHG) spectroscopy in total internal reflection geometry (TIR) to
heterogeneous freezing research. It allows to monitor the evolution of water
structuring at solid surfaces at low temperatures prior to heterogeneous ice
nucleation. Apart from the possibility of investigating temperature
dependence, a major novelty in our setup is the ability of measuring
sheet-like samples in TIR geometry in a direct way. As a main experimental
result, we find that our method can discriminate between good and poor ice
nucleating surfaces. While at the sapphire basal plane, which is known to be
a poor ice nucleator, no structural rearrangement of the water molecules is
found prior to freezing, the basal plane surface of mica, an analogue to ice
active mineral dust surfaces, exhibits a strong change in the nonlinear
optical properties at temperatures well above the freezing transition. This
is interpreted as a pre-activation, i.e. an increase in the local ordering
of the interfacial water which is expected to facilitate the crystallization
of ice at the surface. The results are in line with recent predictions by
molecular dynamics simulations on a similar system. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|