Speaker
Description
The unique physical and chemical properties of interfaces are governed by a finite depth that describes the transition from the topmost atomic layer to the properties of the bulk material. Understanding the physical nature of interfaces thus requires detailed insight into the different molecular structures, chemical compositions, and physical processes that form this interfacial region. Such insight has traditionally been difficult to obtain from experiments, as it requires combination of structural and chemical sensitivity with spatial depth resolution on the nanometer scale.
Here we present a new vibrational spectroscopic approach that can overcome these limitations [1]. By combining phase-resolved Sum- and Difference-Frequency Genera¬tion spectroscopy and selectively determining different nonlinear interaction pathways, we can extract precise depth information on the nanometer scale and correlate these to specific vibrationally resonant modes of interfacial species. We first demonstrate the applicability and precision of this technique in experiments on selected model samples. In the second part we present depth resolved measurements on charged air-water interfaces with different surfactant molecules and study the spatial extend and com¬position of the interfacial regions in these systems. Based on the results we can analyze the spatial evolution of the electric potential normal to the interface and draw conclusions on the electrostatic properties of these aqueous interfaces.
References
[1] V. Balos et al., J. Phys. Chem. C, 126, 26, 10818–10832, (2022).
| Abstract Number (department-wise) | PC 16 |
|---|---|
| Department | PC (Wolf) |
