Ultrafast Dynamics Lab
Taiha Joo (Chemistry)
Atoms, which comprise the basic building block of virtually all materials, measure less than one nanometer (1 nm = one billionth of a meter) long but are capable of moving at the speed of 1 km per second. The only possible way to measure the movement and vibration of such microscopic particles within the flash of a moment, is by projecting light on them within extremely short intervals and observing how they change. To accurately discern the changes they undergo, this process should be performed at the femtosecond (a quadrillionth of a second) level.
The Ultrafast Dynamics Lab, headed by Professor Taiha Joo, leverages ultrafast laser spectroscopy to accurately seize the precise moment when quanta quickly move within a variety of materials from micro-sized molecules to larger-sized organisms. Harnessing the power of spectroscopy both enables researchers at the Lab to observe the reactions and changes in materials in response to the wavelengths of light, and brings the Lab one step closer to understanding the quantum dynamic phenomena of quantum excitation that occurs as a result of quanta receiving energy. Another main research topic at the Lab is in the observation of interferences between quanta, which is also referred to as ‘coherence’.
The movement and characteristics of quanta relate to the molecules within a material causing a variety of chemical reactions. For instance, the movement of transition metal complexes used in photovoltaic energy conversion is governed by quantum dynamics in the process of sunlight being converted into energy. Rhodopsin, a pigment found in the rods of the retina that serves as a photoreceptor, triggers chemical reactions when it receives light, and this is what enables our eyes to recognize light. It was confirmed that its measurement is impacted by the wave function of the nucleus.
Making observations in the quantum domain is only possible when the pulse, a laser cycle, falls at or below 100 femtoseconds. The Ultrafast Dynamics Lab has developed ultrafast, visible light, optical parametric laser device that delivers the world’s best resolution performance of 20 femtoseconds, and is using this advanced device for analysis. Conversely, work is also underway to develop a laser device that does not simply observe, but actually coordinates reactions. If we can identify the amount of energy required in the modification of chemical reactions, we can also do just the opposite and inject such energy through laser and trigger chemical reactions.
Each and every one at the Lab – from the lead professor to individual students – has their very own device they can use to perform experiments on and is free to engage in whatever experiment interests them. The process by which they use their knowledge to go about assembling individual optical components to eventually fabricate and utilize the experimentation device of their choosing, could be compared to the stacking of Legos. The recognized merits of their research excellence in quantum dynamics extend well into the scientific community: the Lab was designated last year as the ‘quantum dynamics research center’ under the leading research center project of the Ministry of Science and ICT.
Head of Lab
Chemistry Building 124