Photophysics and Photochemistry examine matter after it has been excited by light. Light excites the molecules to a higher electronic state, and the molecules show the tendency to relax and/or react; chemical reactions initiated by light are then investigated within photochemistry as a scientific discipline. The knowledge obtained via photophysics and photochemistry is used in various directions and applications:
Compounds on ice: Ice and snow, the solid forms of water, are very interesting reaction media. Organic compounds are mostly expelled from the inside to the surface of ice and to the veins between ice crystals. We study the compounds in these compartments by absorption, emission, microscopy, and reactivity. These compartments differ from the original solution: the concentration of impurities increases, and the amount of available protons changes. Electrical potential is created on the interface between ice and the solution during freezing. The above facts strongly affect the frozen compounds, whether in natural or human-induced freezing. We investigate the spectroscopy, speciation and compartmentation of compounds on ice to describe ice - compounds interactions.
Photoremovable protecting groups are the compounds that fall apart when excited by light. They can be useful when a compound is required to be released at a particular place and time. To apply photoremovable protecting groups, the release mechanisms must be known. We investigate these by means of time resolved spectroscopy, a tool observing what happens just after the absorption of light and defining the rates of the given process. For this purpose, we use nanosecond and femtosecond ultrafast transient absorption spectroscopy, fluorescence spectroscopy, products analysis, and other methods.
Actinometry counts the efficiency of photochemical processes. It is much needed for understanding the reaction mechanism and well suited for certain very practical purposes, such as the determination of the amount of light falling upon one’s skin on a sunny day and the useful outcome of a photovoltaic cell.
In most of the activities, a certain amount of data is collected and subsequently processed; we therefore apply some statistics or minimizations. Over time, we progressively attempt to gain full grasp of the procedure.