Ali Ramadhan

Project Lovelace is an open online platform for learning about science and developing computational thinking through programming and problem solving. It is a collection of computational science problems and tutorials taken from all branches of the natural, social, and mathematical sciences. Each problem teaches a scientific application (e.g. locating earthquakes, DNA splicing) and requires the use of scientific insight and some programming skills to solve. Tutorials teach computational methods that students and researchers may find useful (e.g. solving differential equations, Bayesian inference) and may be required knowledge for some problems.

While Project Lovelace is still in development, we are deploying the website and the problems one by one throughout the winter in preparation for a pilot run in April 2017. In addition to the website's recreational aspect we ultimately hope that the problems and tutorials may be used in undergraduate courses, especially to complement courses that lack a computational portion as computational methods have become ubiquitous in almost every field of science.

Have you ever seen a molecule bend or participate in a chemical reaction? If so, probably not directly: single molecules are notoriously hard to observe for any length of time. For my MSc thesis I developed a rigorous computational framework to create movies of individual molecules undergoing chemical reactions using Coulomb explosion imaging (CEI), a technique of studying the ultrafast dynamics of smaller molecules in the gas phase. While CEI has always promised that atomic structures may be measured, in practice no rigorous method is available and instead the momentum vectors are studied. The momentum vectors tell a large part of the story but aren't as satisfying to study as the actual structure everyone seeks so a method of retrieving the structure is highly desirable.

The structure may be recovered by attempting to simulate the CEI experiment backwards in time; however, solving for the molecular geometries constitutes an ill-posed nonconvex optimization problem that is difficult to tackle computationally even for small molecules. I am actively trying different optimization approaches and also collaborating with the Department of Statistics and Actuarial Science on a fully statistical approach using Bayesian inference. So far the statistical approach seems more promising as it will allow for the inclusion of measurement uncertainty which every previous study has neglected and seems to scale well to larger molecules (Ramadhan, 2017).

The geometries and dynamics of small gas molecules may be studied by Coulomb explosion imaging (CEI), providing a means of directly probing the atomic structure and dynamics of smaller molecules in the gas phase, a regime where no method is viable. CEI is usually performed using ultrashort laser pulses (~10⁻¹⁵ s) with the goal of "blowing up" the molecule as fast as possible to minimize the disturbance to the molecule and ensure accurate imaging of the atomic structure.

As a proof of principle, we were able to use single X-ray photons from the Canadian Light Source synchrotron to study the dynamics of dissociative ionization in the OCS molecule using CEI. The use of single X-ray photons led to faster ionization and "blow up" compared to short laser pulses, showing promise for greater temporal precision in CEI experiments. It also allowed us to identify a surprisingly rich set of ultrafast molecular dynamics for the first time (Ramadhan et al., 2016).

The traditional synthesis method for polyynes, an allotrope of carbon with chemical structure (−C≡C−)_n, is a challenging and dangerous multistep procedure that provides little control over the their end-caps. Yet polyynes are of great interest in interstellar chemistry and especially in nanotechnology as potential elements for molecular machines and carbon cluster precursors. Their end-caps may endow them with extra functionality and so a safe and controllable synthesis procedure is highly desirable.

By irradiating different liquid solvents with short laser pulses, we are able to easily synthesize long-chain polyynes and demonstrate end-cap control for methyl caps. Using high-performance liquid chromatography (HPLC), we have confirmed the synthesis of polyynes up to C₁₈H₂ and methyl-capped polyynes up to HC₁₄CH₃. This opens the possibility for controlling the synthesis of other polyyne molecules and their efficient mass production (Ramadhan et al., 2016).

Graphene has attracted an enormous amount of attention over the past decade owing to its peculiar properties and vast applicability. However, large-scale single layers of pristine graphene are difficult to obtain and thus much research has focused on graphene oxide gels which may be used to produce high-quality graphene. These gels have their own applications too, such as drug delivery and sensor engineering. To satisfy the large demand for graphene oxide gels, an efficient production method is highly desirable.

By irradiating aqueous graphene oxide with femtosecond laser pulses, we were able to convert the solution into a gel with physical and chemical properties comparable with those of a monolayer graphene sheet. We were also able to control the properties of the synthesized gel by simply tuning the laser pulse's properties allowing for the production of different gels suitable for building nano-sized graphene photodetectors and transistors (Ibhrahim et al., 2014).