Fully funded PhD studentship

 

Femtosecond Photoelectron Spectroscopy of Fullerenes

 

Eligibility: UK and other EU nationals only.

 

Supervisor: Prof. Eleanor Campbell, School of Chemistry, University of Edinburgh

(Eleanor.campbell@ed.ac.uk)

 

To start as soon as possible

 

Fullerenes are nanomaterials that have properties intermediate between those of large

molecules and those of bulk materials. They are becoming increasingly important as

electron-acceptor constituents of organic solar cells and doped fullerene crystals show the

highest critical temperatures of any “organic” superconductors. In spite of their

considerable interest as new organic electronic materials, surprisingly little is known

about the fundamental properties of the excited electronic states of the molecules and

how these develop into band structure as aggregates or crystals are formed. Evidence has

recently been found, using scanning tunnel microscopy, for the presence of diffuse

hydrogenic orbitals associated with fullerenes deposited on a metal substrate. These so-

called “superatom” states (SAMO) are distinct from the molecular s-and p-orbitals that

form through hybridization of the s and p orbitals on the carbon atoms. Instead of being

bound to individual carbon atoms the SAMOs assume the radial and angular distributions

of spherical harmonic functions that are defined by the central potential of the hollow C60

core and thus look like large, relatively simple atomic orbitals. When the fullerene

molecules self-assemble into chains, the diffuse orbitals are seen to readily combine into

delocalized bands and are predicted to play an important role in defining the electronic

properties of fullerene-based materials. We have recently found evidence for the presence

of these SAMOs in gas phase photoelectron spectroscopy of fullerenes with fs laser

pulses. Gas phase studies have the potential to provide more detailed information about

these unusual molecular states and will provide a stringent test of theoretical predictions.

 

This project, funded by the Leverhulme Trust, will expand on the initial investigations to

study the properties of SAMOs for a range of hollow fullerene-based molecular systems

(functionalized fullerenes, endohedral fullerenes, small carbon nanotubes). The aim will

be to understand how the properties of the orbitals can be tuned by modifying the

fullerene cage, ultimately leading to the development of materials with specific electronic

properties. The project will combine experiment and theory. Advanced experimental

techniques such as velocity map imaging photoelectron spectroscopy using amplified,

wavelength-tunable fs laser pulses will be used to probe the properties of the SAMO

excited states. The experimental work will be complemented by theoretical calculations

of photoelectron angular distributions using time-dependent density functional theory.

 

You should have, or be expecting to achieve, a first or upper second class Honours

degree, or equivalent, in chemistry, physics or chemical physics.

 

Please address informal enquiries to Prof. Campbell. For the formal application

procedure see: www.chem.ed.ac.uk/studying/postgraduate_research/apply.html.

 

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