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Study of Photosynthesis by Flash Photolysis (CAT#: STEM-ST-0324-WXH)

Introduction

Photosynthesis is a biological process used by many cellular organisms to convert light energy into chemical energy, which is stored in organic compounds that can later be metabolized through cellular respiration to fuel the organism's activities. The term usually refers to oxygenic photosynthesis, where oxygen is produced as a byproduct, and some of the chemical energy produced is stored in carbohydrate molecules such as sugars, starch and cellulose, which are synthesized from endergonic reaction of carbon dioxide with water. Most plants, algae and cyanobacteria perform photosynthesis; such organisms are called photoautotrophs. Photosynthesis is largely responsible for producing and maintaining the oxygen content of the Earth's atmosphere, and supplies most of the biological energy necessary for complex life on Earth.




Principle

Flash photolysis is a pump-probe laboratory technique, in which a sample is first excited by a strong pulse of light from a pulsed laser of nanosecond, picosecond, or femtosecond pulse width or by another short-pulse light source such as a flash lamp. This first strong pulse is called the pump pulse and starts a chemical reaction or leads to an increased population for energy levels other than the ground state within a sample of atoms or molecules. Typically the absorption of light by the sample is recorded within short time intervals (by a so-called test or probe pulses) to monitor relaxation or reaction processes initiated by the pump pulse.

Applications

Used to study light-induced processes in organic molecules, polymers, nanoparticles, semiconductors, photosynthesis in plants, signaling, and light-induced conformational changes in biological systems.

Procedure

The process of laser flash photolysis can be divided into three steps: absorption, excitation and decomposition.
First, when the laser beam hits the surface of the material, the photons will be absorbed by the material, making the material molecules or atoms in an excited state.
Then, the material molecules or atoms in the excited state will transition to a lower energy level state through spontaneous emission or excitation by external photons.
Finally, the molecules or atoms of matter will release energy during the transition process, which will break down into smaller molecules or atoms.

Materials

Flash Photolysis Spectrometer