Physical Chemistry Lab Report Example | Topics and Well Written Essays - 1750 words - 3

Physical Chemistry - Lab opus ExampleChemical electronic transitions that are usually induced through the submersion of visible accrue spectrum result in excited state molecules. In the process energy is abstracted, dissipated or both. The absorbed energy must be released to return the excited species back to the original ground state. Typically, on absorption of light at their absorption maxima, dye molecules exhibit long excited state lifetimes and emit ray of light at longer wavelengths (fluorescence or phosphorescence). The excited state of the luminescent dye can be satisfied by an energy transfer mechanism upon collision with oxygen molecules 1As a result, the intensity of radiance is reduced along with the lifetime and the degree of quenching is proportional to the oxygen concentration. Fig. 1 shows a ceremonious diagram of an optical oxygen sensor. The active components of the sensor are the luminescent dye encapsulated in a polymer medium, a light source (commonly a LED or laser) for exciting the dye at a particular wavelength, (550800 nm) 2, a photodiode to detect the fluorescent radiation and an optical fiber for the transmission of light. The quenching of the lambency can be characterized by the Stern-Volmer eqn. 3Figure 1 Schematics of an optical oxygen sensor. (1) Gas or tranquil path, (2) Lumophore dispersed on oxygen permeable membrane, (3) lens and filter, (4) exciting radiation, (5) fluorescent radiation, (6) optical fiber, (7) LED/Laser, (8) photodiode, and (9) pompIn a typical ground electronic state is a singlet (all electrons paired). Electronic excitation results in an excited state singlet that may undergo internal conversion to a lead state. Due to the forbidden nature of a triplet singlet transition, the triplet state may come through for a substantial length of time. The emission from this state is known as the phosphorescence. Fluorescence refers to the emission from