What factors determine whether or not an interstellar cloud collapses to form a new star? How do migratory birds sense the Earth's magnetic field in order to navigate across thousands of kilometers of unfamiliar terrain? These seemingly disparate questions, and many more, can in fact be investigated using a single set of tools. My research combines optical spectroscopy and mass spectrometry to experimentally study the key molecular constituents of important biological and astrophysical systems. This approach, known as action spectroscopy, provides information not only about the absorption spectra of these molecules, but also what happens to the molecules after a photon is absorbed. Such light-activated processing of molecular ions lies at the heart of many important chemical reactions both in biological systems and in the interstellar medium (ISM), and may leave the molecules in a very different state, setting the stage for further reactions in their respective environments. The results of my research contribute not only to our understanding of the fundamental nature of molecular photophysics, but also to important questions as diverse as molecular hydrogen formation in the ISM and energy transport in photosynthetic proteins.

Luminescence spectroscopy of complex molecular ions in the gas phase

This activity aims to unravel the intrinsic photo-physics of complex molecular ions in the gas phase, free from the confounding influence of a solvent or protein micro-environment.

I currently focus on three types of systems:

  • Intrinsic biological fluorophores: riboflavin, chlorophyll...
  • Extrinsic fluorophores used in bio-imaging and labeling applications: rhodamines, phenoxazines, xanthenes…
  • Astro-molecules: Polycyclic Aromatic Hydrocarbons, fullerenes...

I am developing a new instrument for measuring luminescent light emission (i.e. fluorescence and phosphorescence) from cryogenically cooled, laser excited, gas-phase molecular ions. This is a capability with tremendous potential which is currently possible in only a handful of labs worldwide. This new apparatus, called the Cryogenic StockhOlm Luminescence (CryoSOL) instrument, will be unique in its capability to cool molecular ions to internal temperatures below 10 K.