Question

In a chemiluminescence lab do any factors completely stop light generation? If so, which ones?

Answer 1

Ans-

When you snap a glow stick and it begins to glow, the light produced is an example of chemiluminescence (see Figure 5). Glow sticks comprise a plastic tube containing a mixture including diphenyl oxalate and a dye (which gives the glow stick its colour). Inside the plastic tube is a smaller glass tube containing hydrogen peroxide. When the outer plastic tube is bent, the inner glass tube snaps, releasing the hydrogen peroxide and starting a chemical reaction that produces light (see Box 2). The colour of light that a glow stick produces is determined by the dye used (see Box 3).

Chemiluminescence reactions, such as those in glow sticks, are temperature-dependent. The reaction speeds up as the temperature rises – snapping your glow stick in hot water will produce a fantastic glow, but it will not last as long as it would at room temperature. Conversely, the reaction rate slows down at low temperature; this is why keeping your glow stick in the freezer for several hours can allow the stick to glow brightly again when it is removed and warmed up, long after it would otherwise have stopped glowing. The reaction does not stop completely in the freezer, but it does slow down so that the glow is barely detectable.

Chemiluminescence: A type of luminescence in which the electrons are excited by a chemical reaction

Fluorescence: A type of luminescence in which the electrons are excited by light, e.g. in the security markings on banknotes.

Luminescence: The production of light, usually at low temperatures, for example by chemical reactions or electrical energy. Incandescence, in contrast, is light generated by high temperatures.

Phosphorescence: As fluorescence, but the glow lasts for longer (according to some definitions, over 10 nanoseconds), for example glow-in-the-dark stickers.

Photon: A quantum (packet) of light energy.

When up to 5% water-DMSO solution was employed, excellent results for the chemiluminescent reaction were obtained, but as water concentration increased towards 20%, the chemiluminescent light became quenched [1]. Water concentrations above 20% also quench the light completely. Sodium or potassium hydroxide react with luminol in a regulated DMSO-water solution to form the dianion of luminol as shown in the figure. In the presence of air, the entire fluid bursts into light. Best results are achieved by using about five milligrams of luminol per ml of fluid.