Speaker
Description
Liquid microjets have revolutionized research on neat water and aqueous solutions, by enabling the use of methods requiring a vacuum environment for their investigation. One example is liquid-jet photoemission (PES) which became a rapidly expanding field recently.[1] So far, microjets in vacuum were produced by pushing the liquid sample through a thin (10-40 µm diameter) nozzle with a cylindrical cross section. Consequentially, a thin round jet is formed and by virtue of its curvature liquid jet PES samples over all take-off angles with respect to the surface normal. Such averaging is disadvantageous when properties caused by an alignment of solvent molecules or solutes at the surface are of interest. A premier example are changes of the work function of a liquid caused by alignment of molecular dipoles at its vacuum interface.
In order to widen the scope of liquid-jet PES, over the last four years we have constructed a set-up that produces a flat liquid sheet suitable for a wide range of experiments, requiring a planar solution surface. Technically a planar, leaf shaped section of a microjet with mm-size forms when two conventional, round jets collide under a sharp angle. We will present our design of a flat jet, and will show different projects that crucially depend on its unique properties.
1. In liquid jet PES, the application of a bias voltage to one or both of the colliding microjets allows to bias the two sides of the planar leaf differently, and to produce an electric field across the jet (between the two planar surfaces) allowing to potentially align molecular dipoles in the liquid.
2. Since the jet is flowing with a velocity of approximately 80 m/s its surface is perpetually replenished, thus creating a pristine target for the investigation of liquid surfaces by sum frequency generation and other non-linear infrared techniques.
3. Introducing two chemically reacting samples via the two colliding jets allows to investigate reactions along the leaf, i.e., between the separating liquid – liquid interface. Here, temporal information is encoded in the spatial coordinate in the stream’s direction.
[1] R. Dupuy, C. Richter, B. Winter, G. Meijer, R. Schlögl, and H. Bluhm.
J. Chem. Phys. 2021, 154, 060901
| Abstract Number (department-wise) | MP 21 |
|---|---|
| Department | MP (Meijer) |
