The task to sort molecules can be quite challenging if they are very similar. This is even more the case if you want to sort a single molecular species according to its three-dimensional structure. The problem is that for most molecules a number of these so-called conformers are present and that they easily interconvert at room temperature. In a new study we propose how such a sorting can be achieved with molecular interference. We show how internally cold beams populated with just a single structure can be prepared. These might open new vistas for structure-sensitive collision studies. More information can be found here.
Our study on testing multi-path interference with massive particles has attracted a lot of attention since it was published two weeks ago. The latest is an article in Physics World by Edwin Cartlidge.
Born’s rule is one of the cornerstones of quantum physics. Needless to say that a potential violation of this rule might point to something very interesting happening. In a brand new publication we report about the first explicit test of this rule with matter-waves. Using a special slit mask manufactured by Ori Cheshnovsky at the University of Tel Aviv, we were able to state the first bounds on the impact of non-standard quantum mechanics. More information can be found here.
The second part of the series on matter-waves covers … matter-waves! What is a matter-wave, who came up with the idea, and why is it so hard to observe them? Find the answer here.
This week I will start a little series of posts on matter-wave optics, starting from the very basics, that is a phenomenological review of what distinguishes a wave from a particle. Over time I will discuss a number of concepts that are fundamental to the regime of quantum mechanics but rather unintuitive in our everyday lives. Let’s see where it takes us.
This week starts with waves.
When you introduce a substituent to an aromatic system in organic chemistry you are mostly interested in the effect on the aromatic. The reason for this is that substituents are often attached in specific positions to steer the outcome of a following reaction.
In this study we examined the interplay between indole and a methoxy substituent. Depending on its position at the ring system, the methoxy group alters the energetic position of the excited states of indole by about 2500 cm-1. Interestingly, there is also a position-dependent influence of indole on the substituent. We observe that the relative energies of the conformers and their barriers for interconversion depend strongly on where the methoxy group is located at the chromophore. With this we can explain why for 4- and 5-methoxyindole only one conformation is observed in jet-experiments, while both conformers are present for 6-methoxyindole. More information can be found here.
In these lecture notes we review recent developments in far-field diffraction at a single nanomechanical grating and Kapitza-Dirac Talbot-Lau interferometry. Among others, it covers the following points:
- What is the influence of the van der Waals attraction on the matter-wave and how can we reduce it?
- Why are mechanical gratings not the optimal choice for biomolecules?
- What happens when a large molecule absorbs a photon in a standing light wave?
- How can absolute absorption cross sections of large molecules be measured in a matter-wave interferometer?
Additionally, we discuss our efforts to produce slow beams of intact biomolecules – a veritable challenge as a lot of biomolecules such as amino acids or peptides decompose when they get too hot.
The lectures notes will be published in press in “Les Houches Summer School, Session CVII–Current Trends in Atomic Physics, July 2016”, but you can find an electronic version also on the arXiv.