How would I describe the research we do to a friend? We shoot molecules with lasers.
How would I describe the research we do to a friend? We shoot molecules with lasers.
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Silicon Oxides
Silicon Oxides
Simple silicon oxide systems are key reactive intermediates in the earth's upper atmosphere and interstellar environments. Moreover, they are key species in industrial processes involving chemical vapor deposition. Currently, theoretical characterizations of even the simplest silicon oxide offer conflicting views, and there is limited experimental spectroscopic information on even the simplest systems in this family for comparison. In this project, we will address this issue by detecting and subsequently characterizing the physical properties of simple silicon oxide systems through a synergistic effort of gas-phase spectroscopy coupled to a complementary theoretical program.
Laser ablation pulsed discharge nozzle tip
Refractory Metal Carbides
Refractory Metal Carbides
From met-cars and the development of novel nanomaterials, to the activation of hydrocarbons, and the formation of fullerenes an understanding of the interaction of carbon with metals is important. With the difficulty in modelling bulk metal carbide systems it is hoped studying simpler MnCn type systems which are amenable to spectroscopic and computational studies might give insight into their structure and bonding. Astrophysically in carbon rich environments, it is these simpler systems that condense out forming the seeds to dust grains that are present in such astrophysical objects as circumstellar shells and proto-planetary discs. Of particular interest to our research group is the structure, bonding and electronic properties of magnesium, titanium and iron carbide systems.
Transition metal doped silicon clusters
Transition metal doped silicon clusters
There is great interest in overcoming the Shockley-Queisser limit and increasing silicon-based solar efficiency. While singlet fission and triplet-triplet annihilation hold promise, several technological issues remain. Another promising area is doping amorphous silicon wafers with d-block transition metals whose band gap is an intermediary to that of silicon. In this project optical spectroscopy in combination with computational methods (DFT and coupled-cluster) are used to identify key gas phase intermediates in the plasma-enhanced CVD process.
Diffuse Interstellar Band Carriers
Diffuse Interstellar Band Carriers
Maybe the greatest mystery and challenge in astrochemisty today, since their discovery in the early 2oth century, is the quest to decipher the scientific clues and assign carriers to the series of absorption features that span the visible and near infrared region collectively known as the diffuse interstellar bands. While there has been a number of candidates suggested - carbon chains, polycyclic aromatic hydrocarbons and fullerenes - and a rich history of experiments and theoretical calculations on them it was not until recently that two of the approximately four hundred features were assigned to C60+. To find the answer to, "What is the carrier of the other unassigned features?" gas phase optical spectroscopy is required on possible candidate systems.
Spectroscopy for Knowledge
Spectroscopy for Knowledge
There are many questions that can be answered by the application of gas phase spectroscopy. Some that we are pondering are:
Is it possible to stop a reaction from occurring in the gas phase and study the pre-reactive intermediate?
What is the binding energy between two isolated molecular units?
What is the solvation mechanism of aromatics?
Gas hydrate formation at low temperatures and pressures. Is it possible?
What is the role of high energy states and structures in the chemistry of atmospheric species?
How is soot formed in the combustion of hydrocarbons, and what is the role of cations and other open shell radicals?
Electron flow in molecular systems. What controls excimer formation and can it be stopped.
What is the mechanism for triplet annihilation and singlet fission? Does it occur in the gas phase or is it a condensed phase mediated process?
Image of NO from the dissociation of NO2 at 355nm
51262 Ethylene oxide hydrate
REMPI-TOFMS Al2O Spectrum
Integrated YAG pumped dye laser
2D-LIF-DF of nickel oxide systems.
Initial methane solvation of anisole
Experimental Methods
Experimental Methods
Systems of interest are produced by laser ablation, pulsed discharge or the combination of laser ablation - pulsed discharge.
Systems of interest are characterized by fluorescence techniques such as 2D-LIF-DF spectroscopy, and the mass selective technique REMPI-TOFMS. Additional characterization techniques available are ion imaging, and matrix infrared - UV/Vis spectroscopy.
355nm tripling cell
Dual pulsed nozzle source
Ion imaging system
4K matrix isolation chamber
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