PhD position: Stability of confined water layers in hydrophobic nanochannels

The Faculty of Science and Technology (700 faculty members, 1100 students) offers a range of bachelor and master courses (NanoTechnology, Applied Physics, Chemical Engineering and Technical Medicine). The faculty’s research is organized in three of the university’s interdisciplinary research institutes: MESA+, MIRA, and IMPACT. These institutes increase the vitality of research by enabling collaboration between programs and disciplines, by providing shared facilities, and by attracting funding for joint projects. They also provide a conduit to industrial and other external
partners.

*PhD position: Stability of confined water layers in hydrophobic nanochannels*

*PhD project*

The properties of water in the vicinity of hydrophobic surfaces are at the origin of many important and poorly understood phenomena. They play an crucial role in the solvation of hydrophobic molecules, attractive hydrophobic forces between macroscopic surfaces, the self-assembly of micelles and lipid membranes, and – last not least - in the folding of proteins and in the transport of water and ions through membranes, i.e. in some of the most central processes in living organisms. Despite the
relevance of the subject and the enormous amount of work in the field, many fundamental aspects are still controversial. simple estimate based on bulk properties shows that liquid water is thermodynamically unstable between two hydrophobic surfaces for separations of less than approximately 1µm. Nevertheless, confined water layers should remain stable down to a distance of about 1nm. This is generally attributed to excessive nucleation barriers for vaporization.

In this project, we want to study the stability of liquid confined water layers using a new experimental tool, namely hydrophobic nanochannels etched into glass with a thickness ranging from a few up to a few tens of nanometers. A Fabry-Pérot interferometer incorporated into the nanofluidic chip will allow for measuring the refractive index of the fluid in the channel as a function of both time and position. By varying the temperature and pressure we will force the liquid to evaporate and follow the appearance and growth of gas or vapor bubbles for various conditions (dissolved gas; dissolved ions; pH). To obtain additional information about the dynamics of the transition, we will follow temporal fluctuations of the refractive index (with MHz time resolution) as well as global electric properties of the
nanochannels.

*Requirements*

We are looking for a strong and highly motivated PhD student with a background in physics or physical chemistry. The practical work will be primarily experimental, requiring a high level of technical skills regarding high resolution optical measurements, fabrication, and general surface and sample preparation. Physical modeling of the results falls in the realm of thermodynamics of phase transitions and statistical physics.

*Conditions of employment*

In accordance with the university regulations for academic personnel, the gross salary of a Ph.D. student is € 2,042 in the first year to € 2,612 in the last year.

*Applications*

For more information and application, please contact Prof. dr. Frieder Mugele (+31-53-489- 2106; f.mugele@utwente. nl). Applications should consist of an application/ motivation letter as well as detailed CV (resume). Please send you application before *Oct 1**th** 2009. *Vacancy number 09/183.

Please quote 10 Academic Resources Daily in your application to this opportunity!