(2>A^}jl <Uil aJJW Sudan Academy of Sciences, SAS Council of Engineering Research and Industrial Technology Development of Raman Spectrophotometer By A1AKHIB IBRAHIM ADAM (B.Sc. Honours in Electronics 2003) University of Elneelian A thesis submitted to the Sudan Academy of Sciences in fulfillment for the requirements for Master of Science in Electronic Engineering Supervisor Dr. El- Siddig Tawer Kafi May 2008 Development of Raman Spectrophotometer By ALAKHIB IBRAHIM ADAM Rxamination Committee Name Title Signature Dr. Mubark Clmahal External lixaminer Dr. Relal Kabashi Internal Examiner Dr. Siddig Tawer Supervisor Date of Examination 21/05/2008 ~±JS (j^kjll M ^ 53: AJV! cjkaa 1 DEDICATION THIS THESIS IS DEDICTED WITH LOVE TO THE SOUL OF MY MOTHER 11 AKNOWLEGENT With a deep sense of gratitude, I would like to express my sincere thanks to my supervisor Dr.Siddig. T. Kafi for his expert guidance, availability and continuous support during the work of the research. I thank Dr.A.Artolui for his valuable suggestions and technical support. Also I would like to thank Dr.rbrahim .Alimam for his helpful in the electronics sections. Also I would like to express my thanks to Mrs. Abdel-Sahki for his assistance during my lab work. Mostly, I extend my thanks to all my family and friends for their underlying support and encouragements. Finally, I thank every one contributed to making this research possible. in ABSTRACT In this work, the Raman spectrophotometer HG.2S Jobin Yvon rebuilt and developed, the Raman setup provided as a gift for Neelian University from Amsterdam University. The main parts, which were replaced, include monochromator, an air-cooled photomultiplier tube RCA IP 28, log amplifier, handscanning, labVIEW card for computer interfacing. The components assembled and the whole device was tested successfully. The developed setup was checked using some standard solutions, which showed perfect consistency with literature in the references and published papers. Solutions included hexane, cyclohexane, Carbon tetrachloride, benzene and sodium sulfate . IV 4ji>aL=u ^^ijJall Jj^-w^U (jLolj jl^a* jJjiaJj pliJ ojlcj aj UJ^ill |j& ^ jjjaxill aUajll t r-l-N~lJ lA jtalklj jlgjaJb 4j-<aliJl ?.t^a.Vt ?-}<*? xjn-^l aJ OJJJK ,*-^J t^jLji^AjSalLkJill t(jl >m^g ll (^A duJuklujI (Jill <JJ]1^A1I ajj-^ji ,*-|\l djllLalJ (jj_^iill 4^j_JJ__)SJ! V List of Contents Title Page Koran i Dedication ii Acknowledgements iii Abstract in English iv Abstract in Arabic v List of contents vi List of figures x CHAPTER 1 INTRODUCTION 1.1 Spectroscopy 1 1.2 Raman spectroscopy 2 1.3 Historical review of Raman spectroscopy 2 1.4 Raman spectrophotometer 4 1.4.1 Raman spectrometer 4 1.4.2 The detection system 4 1.5 Advantages of Raman spectrophotometer 5 1.6 Applications of Raman Spectroscopy 5 1.6.1 Analysis and Monitoring of chemicals 5 1.6.2 Medical applications 5 1.6.3 Semiconductors 6 1.6.4 Combustion 6 1.6.5 Biology and Biophysics 6 1.6.6 Remote Sensing 6 1.6.7 Industrial applications 7 1.7 problem of the study 7 1.9 Importance of this research 7 vi CHAPTER 2 LITERATURE REVIEW 2.1 The electromagnetic waves: 8 2.2 Dipole radiation 9 2.3 Molecular spectra 9 2.4 Light scattering 9 2.4.1 Mie Scattering 10 2.4.2 Rayleigh scattering 11 2.5 Raman Scattering 12 2.5.1 Classical model of Raman scattering 13 2.5.2 Quantum model of Raman scattering 14 2.5.3Requirement for Raman scattering 15 2.5.4 Depolarization ratios 15 2.5.5 Raman Intensities 16 2.5.6 Why laser in Raman 16 2.6 Raman techniques 17 2.6.1 Raman resonance 17 2.6.2 Stimulated Raman scattering 18 2.7 Raman spectrophotometer 19 2.7.1 Raman spectrometer 20 2.7.2 Light Sources 21 2.7.3 Sample compartment 22 2.7.4 Gratings 23 2.7.5 Diffraction gratings in Raman spectrometers 24 2.7.6 Monochromators 25 2.7.7 Single monochromator 26 2.7.8 Double monochromator 26 2.7.9 Triple Monochromator 27 2.7.10 Types of monochromator configuration in Raman spectrophotometer 28 2.7.1 IChoosing of the Raman monochromator 30 2.7.12 The throughput of the spectrometer and etendue 30 2.7.13 The illuminating of the spectrometer 31 vn 2.7.14 Photomultiplier tube 31 2.7.15 Signal conditioning in Raman spectrophotometer 32 2.7.16 Raman spectrophotometer chart recorders 32 2.7.17 Interface of Raman with a computer 32 2.7.18 Fourier transform (FT) Raman spectroscopy 33 CHAPTER 3 MATERIAL AND METHOD 3.1 Introductions 35 3.2 The original setup of Raman spectrophotometer 35 3.2.1 Description of the original setup 36 3.2 Problems of the original setup 37 3.3 Experimental procedures for developing 38 3.3.1 Alignment of the optical system 38 3.3.2 Detection system 39 3.3.3 Calibration of the PMT RCA IP28 39 3.3.4 Hand scan 40 3.4.5Calibration of the handscan 41 3.4.6 Amplifier 41 3.5 Lab VIEW program 42 3.5.1 Front panel 43 3.5.2 Block diagram 44 3.5.3 Acquisition system 45 3.5.4 Sampling consideration 46 3.6 Operational procedures 47 3.7 Samples 48 3.7.1 Cyclohexane 48 3.7.2 Hexane 48 3.7.3 Benzene 49 3.7.4 Sodium sulfate Na2 S04 49 3.7.5 Carbon tetrachloride CCL4 50 Vlll Chapter four Results ,Discussions and conclusions 4.1 Introduction 51 4.2 Results 51 4.2.1 Sodium sulfate( Na2S04) 51 4.2.2 Cyclohexane 52 4.2.3Hexane 53 4.2.4 Tetrachloride (CCL4) 53 4.2.5 Benzene 54 4.3 CONCLUSIONS 55 REFERENCES 56 IX list of figures Figure (2.1) laser-based Raman spectrometer 20 Figure (2.2) complete monochromator system of Raman spectrometer 25 Figure( 2.3) Single monochromator 26 Figure (2.4) Double monochromator 27 Figure (2.5) Triple monochromator 28 Figure (2.6) Fastie -Ebert configuration 29 Figure (2.7) Czerny Turner configuration of monochromator 30 Figure (3.1) main parts of the Raman spectrophotometer 35 Figure (3.2) JOBIN RAMANOR HG 2S monochromator optical system 36 Figure (3.3) illustrate Czerny -Turner configuration used in Ramanor HG 2S 37 Figure (3.4) the EMI Photomultiplier tube of the original setup 37 Figure (3.5) the original amplifier in the setup before modification 37 Figure (3.6) RCA photomultiplier tube uncooled 38 Figure (3.7) high voltage PMT power supply 39 Figure (3.8) Signal generator in frequency mode used to check the PMT 39 Figure (3.9): Calibration curves of the PMT RCA IP28 40 Figure (3.10) handscan for Raman spectrophotometer 40 Figure (3.1 l)illustrate log amplifier for developed system 41 Figure (3.12) front panel of labview program for Raman spectrophotometer 43 Figure (3.13) labview program for Raman spectrophotometer 44 Figure (3.14) labVIEW card from national instrument ...45 Figure (3.15) illustrate the increase in the data point 47 Fig( 4.1) Raman shift ofNa2S04 51 Fig(4.2) Raman shift Na2S04 from literature 52 Figure (4.3) Raman shift of cyclohexane 52 Figure (4.4) Raman shift of Hexane 53 Fig (4.5). the Raman shift of carbon tetrachloride 53 Fig(4.6): Raman shift of carbon tetrachloride from literature 54 Fig(4.7):Raman shift of benzene 54 x CHAPTER ONE INTRODUCTION 1.1 Spectroscopy Spectroscopy is the science that deals with the interaction of electromagnetic radiation with matter (James etal ,1999). The electromagnetic radiation must be absorbed ,emitted or scattered by the molecules, the radiations is analyzed as a beam of radiation from the source such as laser then passed through the sample , the electromagnetic radiation which existing the sample was measured ,for example in a vibrational absorption spectroscopy , the frequency of the radiation or the spectrum, can be produce and showing the intensity of the exiting radiation for each frequency.(Merlo Park, 1970 ) .The spectrum will show which frequencies of radiation of the molecule, will raise energy to a high vibratonal energy state. Each molecule will have it is own characteristic spectrum, this is making spectroscopy indispensable in analytical chemistry (Wessbuth etal, 1978). Electromagnetic radiations consists of oscillating electric and magnetic fields, both of these fields have the potentials to interact with molecules ,however the magnetic interaction is much less likely to cause transition to occur ,and so the electric effect dominate ,usually in rotational and vibrational spectroscopy transition of interest are those involving the interaction, between the electric dipole moment of the molecule and the electric field of the radiation ,for strong interaction between the molecule and radiation .The electric dipole moment must oscillate at the same frequency as the electric field (John R etal, 1994). In absorption spectroscopy, the photon transfer the energy to the molecules, resulting in transition to a higher energy state or to a lower energy state and the energy lost in this process emitted as photons (James etal, 1999). Molecular posses electronic, vibrational and rotational energy state, for each electronic state there is a set of vibrational states and for each of these is associated a set of rotational states (D.W.Ball,2001 ). Many of this states include transitions between specific range used for studies of chemicals species and are observed by monitoring the absorption or emission of 1 electromagnetic radiation ,composed from discrete packets of energy which we call photon (James's eta/, 1999 ). 1.2 Raman spectroscopy The Indian physict C.V Raman discovered that the wavelength of small fraction of the radiation , scattered by certain molecules, differ from that of the incident beam and further more that, the shift in wavelength depend upon the chemical structure of the molecules, responsible for the scattering .