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 Alexander Nahmad-Rohen

Alexander Nahmad-Rohen

Research student, School of Physics and Astronomy

I am a physics PhD student working in the biophotonics group under the supervision of Profs Wolfgang Langbein and Paola Borri.

My current PhD research is on whether action potentials can be imaged optically and what the physical implications of the optical observations are for the neurons firing them. When neurons activate and send messages to each other or to other body tissues, they do so in discrete membrane-voltage changes that travel down the neurons' axons; these voltage changes are called action potentials. While the most accepted physical model of the action potential is purely electrical in nature, other types of phenomena —mechanical, optical and thermodynamic— have been observed during neural activity. Optical observation by interferometric reflectometry and coherent inelastic (Raman) scattering of light would not only allow noninvasive probing of action potentials (current techniques are electrical and thus involve probing cells with electrodes) but also show the strength of the mechanical and thermodynamic changes neurons undergo when firing, which would allow critical comparison of the aforementioned electrical model with alternative models. My work is both theoretical and experimental and has so far involved developing the theory of interferometric reflectometry for our experimental setup, building a computer programme to analyse interferometric reflectometry data, improving and testing the reflectometry and coherent Raman setups to ensure they are ready for use in my planned experiments, and setting up electrophysiology equipment to use alongside the optical equipment in our lab.

My previous work has involved the dynamics of the interaction between the synthetic biomarker COSAN and live cells (MSc thesis) and a study of the effective refractive index of whole blood and how it can be used for medical diagnosis of conditions that affect blood composition (BSc thesis and publication).

Research interests

Research focus is in optics & biophotonics.

Other topics of interest include (astro)geology, relativity & neurology.


  • 2nd-year physics lab demonstrator (2015–2016 & 2016–2017 terms)


Multiplex coherent anti-Stokes Raman scattering microscopy and its applications to living cells

Wolfgang Langbein

Professor Wolfgang Langbein

Head of Condensed Matter and Photonics Group

Professor Paola Borri

Professor Paola Borri

Professor, Coordinator of the European Marie Curie ETN consortium MUSIQ