0000047672 00000 n
The general approach to this experiment is adapted from D. P. Shoemaker, C. W. Garland, and J. W. Nibler, Experiments in Physical Chemistry, 6th edition, McGraw Hill Co. Inc, NY, 1996, p378. 9. Conjugation (delocalization) impacts the energy required for electronic transitions. HVKO1WJ 0000001720 00000 n
J. Chem. 0000001782 00000 n
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Hence, gamma should be calculated using only compounds from a homologous series (9). /Parent Particle in a Box: Absorption Spectrum of Conjugated Dyes - Physical Chemistry (1) Practical: - Studocu The purpose of this experiment is to determine the value of the empirical parameter and determine the length of a conjugated carbon chain for a set series of Skip to document Ask an Expert Sign inRegister Sign inRegister Home Ask an ExpertNew 0 9. a = (2j + 2)L, C: 1,1-Diethyl-2,2-dicarbocyanine Iodide, N = 2j + 2 = 2(4) + 2 = 10 pi electrons In the case of electrons in the particle in a box there are two quantum numbers, n and spin. });
Educ. 0 0 The purpose of this experiment is to measure the absorption spectra of two series of cyanine dyes and diphenyl polyenes, and to try to correlate the experimental observations using a simple quantum mechanical model. 0000007413 00000 n
Furthermore, when we calculate the theoretical max using a lengthening parameter, gamma, the chemical connectivity of dye 4, being different from that of dyes 1, 2, and 3, may contribute to a less-than-accurate gamma. 13. chloride), 8 x 10- >> R Educ. You MUST fill out the cover sheet fully and correctly to receive credit. Also do not cross contaminate the dye solutions by the using same pipette to transfer different dye solutions. In specific, each AID-ssDNA structure was firstly infiltrated in a hexahedral box, with the minimum distance between the solute and box boundary set to 7 . { "4.01:_Pre-lab_Assignment" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "4.02:_Introduction" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "4.03:_Experimental_and_Discussion_Questions" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "4.04:_References" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "4.05:_Appendix_A_-_Use_of_the_Agilent_100_Series_UV-Vis_Spectrophotometer" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()" }, { "00:_Front_Matter" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "01:_Orientation_to_this_course" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "02:_Introduction_to_Matlab_for_Pchem_Lab" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "03:_The_Treatment_of_Experimental_Error" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "04:_Absorption_Spectrum_of_Conjugated_Dyes" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "05:_Rotation-Vibration_Spectrum_of_HCl_and_DCl" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "06:_Calorimetry" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "07:_Kinetics" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "08:_Molecular_Electronic_Structure_Calculations" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "zz:_Back_Matter" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()" }, { "CHEM301L_-_Physical_Chemistry_Lab_Manual" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "CHEM310L_-_Physical_Chemistry_I_Lab_Manual" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", CHEM_110_Honors_Writing_Projects : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "Chem_201_(Organic_Chemistry_I)_-_Cox" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "CHEM_210D:_Modern_Applications_of_Chemistry" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "CHEM_401L:_Analytical_Chemistry_Lab_Manual" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()" }, 4: Absorption Spectrum of Conjugated Dyes, [ "article:topic-guide", "source[1]-chem-369883" ], https://chem.libretexts.org/@app/auth/3/login?returnto=https%3A%2F%2Fchem.libretexts.org%2FCourses%2FDuke_University%2FCHEM301L_-_Physical_Chemistry_Lab_Manual%2F04%253A_Absorption_Spectrum_of_Conjugated_Dyes, \( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}}}\) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash{#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)\(\newcommand{\AA}{\unicode[.8,0]{x212B}}\). 1,1'-Diethyl-2,2'-carbocyanine iodide (Dye B) Correct the wavelength scale using the calibrations given in the class handout. Molecules of a colored object absorb visible light photons when they are excited from their Gerkin, R. E. J. Chem. 7. << << II8b iDE;@8H%XDIc#,Olf4w73yTjHfHf`a Ch :n@| e~G)
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You only need to turn in your work (with enough context to understand what you are answering), and not the entire Mathcad file. These dyes are typically $100-$300 per gram and so it is important not to waste the materials. 0000008957 00000 n
The absorption spectrum of a series of conjugated dyes is produced by a UV/VIS spectrometer to Figure 3. In this exercise you will explore the spectroscopy of the cyanine dye family, develop a testable hypothesis and then determine the validity of your hypothesis. Evaluate and tabulate the difference between the length of the box calculated from Equation (11) and the length estimated from the number of bonds for each dye. It is advisable not to try to do the peak picking in Excel; it is fairly tedious. So in this case was, 1, 1 Diethyl -2, 2 dicarboncyanine iodide for it has ranged with 700nm. In conclusion, we find that PIB is predictive as long as we apply it to a homologous series. Below are the dyes which we will study Since a linear trend between p and experimental max is shown in both plots, and the experimental and theoretical max match for each compound in each homologous series (Figure 3), our hypothesis that PIB is predictive only when applied to a homologous series is correct. Abstract Particle in a one dimensional box laboratory experiments have traditionally used chemicals like polyenes or cyanine dyes as model systems. Figure 1: The absorption spectra of each conjugated dye. Conjugated dyes are known sensitizers; take care when handling the dyes and wash your hands after handling them. 0 0000004243 00000 n
(3) 1= 2 (4) 2=+1 2 where N is the number of electrons. Bring a floppy disk to record your data. Wear old clothing to lab! /FlateDecode /Nums Note that although your spectra are experimentally determined (and so one would think that they should be shown as individual points), it is common practice to show spectra as solid lines, unless there is good reason to do otherwise. Question: Particle In a Box Lab Help please 1.On a single graph, plot the absorbance spectra of the three dyes. stream It was also seen that the lengths of the box calculated increase with the number of Therefore, if = 1, this signifies that light or any electromagnetic radiation can penetrate a significant distance into the conjugated dyes. The particle-in-a-box (PIB) approximation is a theoretical model that calculates the absorption spectra of conjugated species. The dyes can be run in any order. In this video you will learn how to calculate the maximum wavelength of absorption for a conjugated dye using the particle in a box (PIB) model. We can describe this concept using the equation. Diluted solutions of each dye were analyzed using a UV/VIS spectrometer to And the general solution for an equation of this form is: (x) = A \sin (kx) + B \cos (kx) (x) = Asin(kx)+ Bcos(kx) However, looking at the boundary conditions can help narrow this down. The experiment showed that finding the wavelength of maximum absorbance of a conjugated Absorption of blue light produces the color red while the absorption of red light produces the color blue-green. carbon atoms. (The dyes are CONCENTRATED.). Pope, M., C.E. E = 1.196 10 5 nm kJ 700nm mol = 171.kJ/mol b. The quantum numbers for HOMO(n1) and LUMO(n2) must be found. When we run the routine, we see that for dye 4, the absolute percent error is 0.05% when run with dyes 5 and 6 (Table 2), versus 21.7% obtained when it is grouped with dyes 1, 2, and 3, suggesting that our hypothesis is correct. 0000037506 00000 n
Table 1. 9 >> Some trajectories of a particle in a box according to Newton's laws of classical mechanics (A), and according to the Schrdinger equation of quantum mechanics (B-F). Wear eye protection. You will measure the absorption spectra of a series of conjugated dyes and then use the Particle-In-A-Box (theoretical model) to explain the observed spectra. Donot put all 11 spectra on a single graph as this will be a big mess! where: E is the change in energy, h is Plancks constant, m is the mass of the electron, L is the length of the box and ni and nf are the initial and final quantum numbers. Dye A has 6 electrons and dye B has 8 electrons in their respective pi-bond systems. 0 0 0000044273 00000 n
To calculate the length of the box, assume that the molecule is linear and use 154 pm and 135 pm for C-C and C = C bond lengths respectively.
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