Gas Flow DiagramUniversity of California at Berkeley Physics 111 Laboratory LIF2005.3 Version 2005.3 Copyright © 2005 The Regents of the University of California. All rights reserved Page–1/24 University of California at Berkeley Physics 111 Laboratory LASER INDUCED FLUORESCENCE and RAMAN SCATTERING Revision 2005.3 Fall 2005 This document copyrighted © 2005 The Regents of the University of California. All rights reserved. You must watch the Laser Safety video and sign a form before you use the apparatus in this experiment. Watch the Video on this Experiment Student's Name Partner's Name Pre-lab Discussion Questions It is your responsibility to discuss this lab with a professor or GSI on the first day of your scheduled laboratory period. This signed sheet must be included as the first page of your report. Without it you will lose 1/3 of a letter grade. You should think about and be prepared to discuss at least the following before you come to lab: 1. Describe the processes of absorption and emission of light. 2. Qualitatively describe the structure of a diatomic molecule and how the electronic, vibrational, and rotational energies are manifested in the absorption spectrum, and in the emission spectrum. What electronic and vibrational states of iodine are involved in the absorption spectrum? 3. What is laser induced fluorescence? Can a source other than a laser be used? 4. Qualitatively, what will the iodine fluorescence spectrum look like? 5. What molecular parameters can be derived from experimental observations of absorption and laser induced fluorescence? 6. What safety precautions should be observed while using the laser? Staff Signature Date Completed on the first day of lab? (circle) Yes / No Mid-lab Questions 1. On day 4 of this lab, you should have produced a plot of ∆G versus v" from your fluorescence data. Show it to a GSI ask for a signature. 2. What is Raman scattering? 3. What molecular parameters can be derived from Raman scattering? Staff Signature Date Completed on the fourth day of lab? (circle) Yes / No INCLUDE THIS SHEET AS THE FIRST PAGE OF YOUR REPORTUC Berkeley Physics 111 Advanced Undergraduate Laboratory LIF2005.3 Version 2005.3 Copyright © 2005 The Regents of the University of California. All rights reserved Page–2/24 Physics 111 Advanced Lab Student Evaluation of Experiment Now that you have completed this experiment, we would appreciate your comments. Please take a few moments to answer the questions below, and feel free to add any other comments. Since you have just finished the experiment it is your critique that will be the most helpful. Your thoughts and suggestions will help to change the lab and improve the experiments. Please be as specific as possible, using both sides of the paper as needed, and turn this in with your report. Thank you! Experiment name:_____________________________________________ Date: ________ How was the write-up for this experiment? How could it be improved? How easily did you get started with the experiment? What sources of information were most/least helpful in getting started? Were the reprints appropriate? Did the Pre-lab discussion help? Did you need to go outside the course materials for assistance? What additional materials could you have used? What did you like and/or dislike about the experiment? Would you recommend this lab to fellow student? Why or why not? What advice would you give to a friend just starting this experiment? If the course materials were available over the internet (WWW, FTP, etc), would you (a) have access to them and (b) would you prefer to use them this way? Please circle the abbreviations of the other labs you have done. ATM BRA COM CO2 GMA HAL LIF HOL JOS LLS MNO MUO NLD NMR OPT RUT SHE XRA Overall quality of this experiment? 1 2 3 4 5 Poor Average GoodUC Berkeley Physics 111 Advanced Undergraduate Laboratory LIF2005.3 Version 2005.3 Copyright © 2005 The Regents of the University of California. All rights reserved Page–3/24 LASER INDUCED FLUORESCENCE and RAMAN SCATTERING Revision 2005.3 I. REFERENCES Get the Reprints for this experiment most articles below are in it. 1. R. W. Wood, Physical Optics. Chapter 5, “The Origin of Spectra” is a historically accurate description of what physicists thought about how spectra were produced. In his time, Wood was the world’s foremost experimental physicist in the fields of Light, Optics, and Spectroscopy. 2. Lewis, Palmer, and Cruikshank, Iodine molecular constants from absorption and laser fluorescence, Am. J. Phys. 62, p350 (1994). Read this before you begin the lab, after reading the introductory material in this handout. 3. Compaan, Wagoner, and Aydinli, “Rotational Raman scattering in the instructional laboratory,” Am. J. Phys. 62, 639 (1994). Read this before the mid-lab exercise (before you do the Raman Scattering section of the lab). 4. G. Herzberg, Molecular Spectra and Molecular Structure I. Spectra of diatomic molecules. 2nd ed. D. Van Nostrand Co. Inc. 1950 (QC451.H455 Vol 1 & Vol 2) This is the Bible of diatomic molecular spectroscopy. Vol 1; Read sections of this as necessary; see citations in this write-up and look through contents to decide what to brush up on and QC451.H455 Vol 2 is for Raman and Polyatomic Molecules. 5. R. Eisberg and R. Resnick, Quantum Physics of Atoms, Molecules, Solids, Nuclei, and Particles, 2nd ed. (Wiley, New York, 1985), pp. 423-437. This is a straightforward explanation of Raman scattering. 6. K.P. Huber and G. Herzberg, Molecular Spectra and Molecular Structure IV. Constants of diatomic molecules. 2nd ed. D. Van Nostrand Co. Inc. 1950. This is a comprehensive tabulation of molecular parameters. Use this to check your results. II. INTRODUCTION Molecules in the gaseous state can absorb light when the frequency or photon energy matches the energy difference between two levels. A short time later, the molecules decay to lower energy states and emit photons (fluorescent light) with energies corresponding to energy differences between states. The lower states can be the same as or different from the original state. Observation of frequencies of light absorbed or of these fluorescence photons can tell us about the energy level structure of the molecule. In addition to absorption, molecules also scatter