Lecture

Van Marum Mini Symposium

Dr. Helen Chadwick (Swansea University), Dr. Cristina Díaz (Universidad Complutense de Madrid)

Date: Tuesday 21 October 2025
Time: 09:30 - 12:00
Location: Gorlaeus Building
Einsteinweg 55
2333 CC Leiden
Room: CM.3.23

Schedule 21^st of October:

9:30: Talk by Helen Chadwick
10:30: Coffee break
11:00: Talk by Cristina Díaz

Helen Chadwick: Rotational orientation effects in hydrogen-surface reactions

The most detailed insights into collisions at a molecular level are provided by quantum state resolved experiments, as they remove the averaging over the many degrees of freedom that can influence the outcome of the collision. One quantum state that was particularly difficult to control for ground state molecules is the rotational orientation projection (m_J) state, restricting stereodynamic studies to particular molecules where control techniques have been developed¹.

In this talk, I will give an overview of a magnetic manipulation technique² which allows the rotational orientation of closed shell ground state molecules to be controlled and manipulated before they collide with a surface, with a focus on how it can be used to control hydrogen molecules to perform reactivity studies³. I will present results from recent experiments investigating the stereodynamics of H₂ dissociation, which demonstrate that the reaction probabilities can be changed by changing the m_J state of the molecule.

References

H. Ueta and M. Kurahashi, Angewandte Chemie, 56, 4174 (2017).
O. Godsi, G. Corem, Y. Alkoby, J. T. Cantin, R. V. Krems, M.F. Somers, J. Meyer, G.-J. Kroes, T. Maniv and G. Alexandrowicz, Nat. Comm., 8, 15357, (2017).
H. Chadwick, G. Zhang, C. J. Baker, P. L. Smith and G. Alexandrowicz, Nat. Comm., 16, 4625, (2025).

Cristina Díaz: Engineering Single-Molecule Conduction: The Synergy of Chemistry and Physics

Since the initial discovery that conjugated oligomers could function as active components in electronic devices [1], molecular electronic junctions (see Fig.) have gained attention as promising candidates for innovative technological applications in the field of moletronics [2,3]. The advancement of these technologies depends on our capacity to design and adjust the electronic properties of the junctions as needed. Precise control over the properties of molecule-junctions can be achieved by synthesizing molecules with specific functionalities and creating suitable molecule-electrode contacts using specialized anchoring groups. To separate the effects of these three elements—molecule, anchoring group, and electrode—on the junctions, we conducted systematic investigations by holding two components constant and varying the third.

In this talk, we will discuss the findings from our recent studies where we: i) varied the anchoring group while keeping the electrode material and molecule constant [4]; ii) changed the anchoring electrode-site while maintaining both the anchoring group and the molecule unchanged [5]; and iii) modified the central molecule while preserving the same electrode material and anchoring groups [6,7]. These investigations provide valuable insights into the individual contributions of the molecule, anchoring group, and electrode to the overall properties of the molecular electronic junctions. By systematically varying each component while holding the others constant, we have enhanced our understanding of how these elements interact and influence the junctions' electronic behaviors.

References

A. Aviram & M.A. Ratner. Chem. Phys. Lett. 29 (2), 277 (1974)
L. Sun et al. Chem. Soc. Rev. 43, 7378 (2014)
E. Leary et al Chem. Soc. Rev. 44, 920 (2015)
A. G. Fallaque et al Nanoscale 14, 464 (2022)
A. G. Fallaque et al Appl. Surf. Sci. 646, 158943 (2024)
L. Palomino-Ruiz et al Angew. Int. Ed. 60, 5509 (2021)
R. Casares et al J. Am. Chem. Soc. 146, 29977 (2024)