Sara Freund Receives Prize for Best Master’s Thesis in 2014Portrait
Sara Freund has won the prize for the best Master’s thesis in nanoscale science at the University of Basel. This is the second time the prize has been awarded. The young French scientist, who earned her Bachelor’s in Strasbourg and came to the University of Basel for her Master’s, wrote her winning thesis on using a newly developed non-contact atomic force microscope.
A new microscope
Sara Freund, a 25-year-old scientist from Hegenheim in France, joined Professor Ernst Meyer’s team to write her Master’s thesis in February 2014. She worked with the non-contact atomic force microscope (AFM) that Dr. Gregor Fessler, one of the group’s former doctoral students, had recently spent several years developing. He had successfully used it to conduct friction measurements, but no one had used it in non-contact mode to generate images of different surfaces.
Sara used the new AFM, which works at room temperature, to investigate the surfaces of benzylammonium (BNL) crystals. These organic compounds are the result of a collaboration between the Meyer group and Professor Decurtins of the University of Bern. Gregor Fessler had previously conducted a detailed study of BNL, which (among other distinguishing features) has anisotropic properties. This means the physical and chemical forces in BNL work differently in different spatial directions, a fact that is reflected in the variation in orientation on the surface of the crystals.
A bumpy start
The atomic imaging of BNL proved more difficult than Sara had originally anticipated. Noises and vibrations in the building were the first problem. They interfered with the measurements for months until Sara eventually acquired some insulating underlay. Next, she ran into difficulties with preparing the samples. The standard approach of attaching samples to the holder with glue, for instance, did not work because the glue melted onto the sample when it was heated up. Sara then tried an approach similar to the one that produced graphene for the first time: she used sticky tape to remove a thin slice of hot BNL. This meant she could prepare the samples in a way that would allow measurements in the ultra-high vacuum to succeed.
C60 molecules form islands
Once Sara had successfully imaged the crystals, she investigated how C60 molecules arrange themselves on BNL. She showed that they form relatively small islands, which is different to how they behave on metals or ionic crystals. The islands contain roughly 1,000 to 2,000 molecules and are either triangular or hexagonal in shape. Using the AFM tip, Sara was able to change the shape of the islands by turning triangles into hexagons and vice versa.
Seeing atoms was a dream come true
Sara’s supervisor, Professor Ernst Meyer, is delighted with her work: «Sara really deserves the prize for the best Master’s thesis. She did excellent work and didn’t let the teething problems faze her. Her thesis shows that the new non-contact AFM is ideal for studying sensitive samples.»
Sara is just as fired up as her supervisor. From the moment she first learned about atoms and molecules at school, she dreamed of being able to see them one day. Since completing her nanoscience program, she has gone straight on to the next stage of her academic career. Nine days before taking her Master’s examination in October 2014, Sara began working on her doctoral dissertation in Ernst Meyer’s group. Sara is now using the same microscope – albeit with some alterations and improvements – to study dye-sensitized solar cells in collaboration with the group led by Professor Ed Constable and Professor Catherine Housecroft.
A hard but worthwhile transition
Sara feels at home at the University of Basel and is particularly settled in her working group. She is looking forward to the time she will spend here on her doctoral thesis. She has never regretted moving to Basel for her nanoscience Master’s after earning her Bachelor’s in physics in Strasbourg – even though it meant she had to put in some extra work. «I only did a bit of chemistry in Strasbourg, and no biology at all», Sara recalls, «so it was really tough at first. As well as starting my Master’s program, I also had to catch up on block courses and other Bachelor’s courses. But I knew straight away that I absolutely loved it.» And so she continues her research, still highly motivated and still thrilled at the sight of atoms and molecules.