In my research I focus on the characterisation of various nanomaterials with optical and magnetic resonance spectroscopy. The most important research topics are briefly descirbed below:
- Functionalisation of SWCNTs by endohedral filling:
The unique one-dimensional hollow structure of SWCNTs provides an excellent template for aligning molecules in one dimension, by encapsulating them in the interior SWCNT channel. Many different molecules have been encapsulated, such as water, various solvent molecules that can tune the optical properties of SWCNTs. Most interesting is the encapsulation and alignment of functional molecules, which can photosensitize the SWCNTs (through energy transfer), dope the SWCNTs (through electron transfer) or can create new properties by the alignment of the molecules inside the SWCNTs (e.g. phase transitions, nonlinear optical properties etc. ).
- Chiral sorting of SWCNTs:
Although much progress is being made, synthesis methods each time provide mixtures of different SWCNTs, with very different optical and electronic properties. To embed SWCNTs in actual devices, sorting of SWCNTs by chiral structure and thus also optical and electronic properties is essential. This can be achieved in many ways, using different techniques such as density gradient ultracentrifugation (DGU) and aqueous two-phase extraction (ATP).
- Optical properties of empty and filled SWCNTs:
By changing the endohedral content of SWCNTs, their optical properties can be highly infleunced, e.g. shifting the optical transitions and vibrational frequencies of the SWCNTs. This is investigated in a chirality-dependent manner. Also the intrinsic properties of SWCNTs are being investigated by optical spectroscopy.
luminescence properties of empty and filled SWCNTs
- Endohedral synthesis of graphene nanoribbons and carbon chains:
The hollow structure of SWCNTs can also be used to synthesize linear carbon chains and graphene nanoribbons, which can then be characterised spectroscopically by wavelength-dependent Raman spectroscopy.
- Magnetic resonance spectroscopy of (filled) SWCNTs:
Electron Paramegnetic Resonance Spectroscopy comprises various methods to investigate unpaired electrons, such as present in paramagnetic molecules. Funcionalisation of SWCNTs with paramagnetic molecules, either encapsulated in their interior or adsorbed on the SWCNT walls, thereby provides access to the interior and exterior walls of the SWCNTs. Polarity, orientation and distance between the encapsulated molecules can be revealed, and we showed that the specific interaction of molecules with the SWCNT wall can reveal the metallic-to-semiconductor ratio in SWCNT sampls. More recently we are also focussing on investigating triplet excitons inside SWCNTs usig Optically Detected Magnetic Resonance Spectroscopy.
- Role of Defects in semiconductor devices:
Transport of current through semiconductor devices are related to the spin properties of the charge carriers; which can be trapped in defects within the device. Electrically Detected Magnetic Resonance Spectroscopy can help to unravel the origin of these defects and as such provide useful information to enhance transport in such devices.
Statute & functions
Zelfstandig academ.pers. BOF
- TT. Asst. Research Professor