Dyes and Crimes Pre Lab Introduction The purpose of the first part of this lab is to evaluate three different kinds of chemical light which include phosphorescence fluorescence and chemiluminescence and characterize them by their two components energy source and emitting energy as light The purpose of the second part is to use ink analysis to match ink from an unknown pen with a known one In the first part of the lab the use of polyaromatic acids are absorbed onto filter paper A polyaromatic acid is a hydrocarbon that contains aromatic rings and does not contain heteroatoms Ultraviolet light is then used and shone on this part of dried polyaromatic acids and a glow can be seen This is phosphorescence which excites electrons to a higher energy state then takes use of the forbidden state of energy to emit return to the ground state and takes time to emit light it does not happen as quickly as fluorescence Fluorescence is the process in which light or other radiation is emitted from a certain substance due to an initial incident light shone This can be seen in substances like quinine or other dyes A light can be shone that excites an electron to a higher state or non bonding orbital state and when this electron returns to lower bonding orbital states it emits energy in the form of light causing fluorescence This energy gap relates directly to the wavelength of light emitted due to the dependence wavelength has on energy The larger the gap the more energy it will diffuse when returning to it s ground state and therefore the smaller the wavelength Different fluors or substances that glow when exposed to UV light are used in this lab Homogeneity in solutions is also important in this lab which means that it is mixed well Chromatography plates are used to in order to show illuminated solutions These are examples of cold light or cold luminescence These are chemical lights that do not emit blackbody radiation This radiation is light produced by heating things to very high temperature like a light bulb1 Chemiluminescence is used in this experiment also This type of luminance is used without UV light to excite molecules it uses a reaction of organic molecules This takes the energy from a reaction and transfers them to light Organic reactions make use of oxidation and reduction reactions to produce this energy by the use of very good oxidizers and very good reducers TKDE is oxidized in air and is used DMSO is added to luminol to oxidize it These are a few examples and they both emit a light and color Triboluminescence is also a type of luminesce that is not very well studied or understood but it is known that light is produced from breaking chemical bonds quickly Also halogen lights can be used to emit light when relaxed Also sodium lamps use this idea too The second part of this lab the crime part uses many different chemistry concepts one main one being thin layer chromatography and UV vis spectrophotometry Thin layer chromatography is a method to separate compounds A plate is covered with silica or alumina which is polar A drop of the unknown can be placed on it in a puddle then the solvent moves it up the plate It will then separate the components with respect to polarity and color The Rf factor is used to classify this this is the ration of distance traveled of solvent to distance of compound traveled This also means polar molecules will not have a high Rf factor UV vis spectroscopy is used in this lab which measures peak wavelengths of different solutions to then determine different information about these This type of spectroscopy utilizes shining light through the solutions and measuring peak wavelengths and absorbances and graphs this in a graph of absorbance vs wavelength graph The highest wavelength is the lambda max which is different for different solutions Ink Extraction is also used This utilizes different things like boiling points and polarity of different solutions to extract ink from different solutions Methanol is painted onto different notes in test tubes and then placed in hot water It is then dried and ink is leached off the paper There are many examples of this kind of science in the real world Most glow in the dark toys are examples of phosphorescence lasers can excite things to display fluorescence In the science world these can also be seen In an experiment at the institute of general food chemistry phosphorescence measurements were performed in order to study alanyl residue in tryptophan Fluoresence was also used to study decay kinetics in this study2 In a biology lab chemiluminescence was used for optical aprasensors for quantitative detection of small biomolecules It was used due to its high sensitivity3 Finally in another study to promote ocular health thin layer chromatography was used to measure lipid concentrations of cellular lysates4 This type of study looked at different drugs and tried to help make better use of drugs to increase the number of drugs that were useful Procedure For a complete procedure look to the lab manual1 Procedure Dyes Half Phosphorescence 1 Squirted polyaromatic acids onto two pieces of filter paper over a sink 2 Placed filter paper on hot place on low for 5 15 minutes until bone dry Placed filter paper unter UV lamp Long and Short UV radiation Note do not look directly into the lamp This can cause damage to eyes 3 Observed color under UV lamp then turned off lamp along with intensity and duration of glow Fluorescence 7 Observed beaker of tonic water under UV lamp from the top Described intensity and color of the glow Observed what happened when the lamp was turned off 8 Placed large beaker of water under lamp Observed 9 Added 1 to 3 drops of the concentrated fluorescein solution Shone UV lamp on the solution Observed with UV lamp on and off 10 Added a drop of fluorescein to the beaker of tonic water and observed 11 Placed a chromatography plate containing fluorescent indicating dye under UV lamp 12 Recorded how fluorescence differed from phosphorescence base on previous observations Chemiluminescence 17 Flushed an Erlenmeyer flask with nitrogen by placing the hose from a nitrogen tank in the bottom of the flask for 30 seconds and removed hose quickly 18 Added 2 mL of TKDE Tetrakis dimethylaminoethylene Coated the bottom of the flask with LiCl Stoppered the flask immediately Observed 19 Removed stopped then restoped Swirled Observed Mixed 5mL of Luminol in DMSO with 5 mL of dye in a scintillation vial 20 Repeated step 10 with