CHM580 Chapter 1 Introduction to Spectroscopic Method PDF

ICP-OES CHM580 CHAPTER 1 INTRODUCTION TO FTIR SPECTROSCOPIC METHOD AAS UV-VIS NMR WHY DO WE NEED AN INSTRUMENTAL ANALYSIS COURSE? Scientists involve in chemical analysis samples of interest (analytes) usually a...

ICP-OES CHM580 CHAPTER 1 INTRODUCTION TO FTIR SPECTROSCOPIC METHOD AAS UV-VIS NMR WHY DO WE NEED AN INSTRUMENTAL ANALYSIS COURSE? Scientists involve in chemical analysis samples of interest (analytes) usually ask these QUESTIONS What is this sample composed of? How much of each component is present?  CHM 580 In this course, you will appreciate The methods and instruments used to make measurements The principles behind these measurements SPECTROSCOPY SYLLABUS: Introduction to spectroscopic method Quantitative aspects of spectrochemical measurements Atomic Absorption Atomic Emission UV VIS Molecular Luminescence Spectrometry Infrared Spectrometry Raman spectroscopy Nuclear Magnetic Resonance (NMR) Spectroscopy Molecular Mass Spectroscopy Recommendation book: And any basic analytical chemistry book  ASSESSMENT 1 test (20 %) 1 final exam (40 %) 1 assignment (20%) 1 lab report (20 %): 4 experiments EXPECTATION AT THE END OF THE COURSE: Explain concepts and theories in atomic and molecular spectroscopic instrumentations. Apply spectroscopic instrumentation techniques to obtain qualitative and quantitative information about the composition and structure of matter. Conduct practical skills in areas of spectroscopic methods of analysis. Demonstrate communication skill in written report related to spectrochemical methods of analysis. CHM580: SPECTROCHEMICAL METHODS OF ANALYSIS  OUTLINE 1.1 General properties of electromagnetic radiation 1.1.1 Wave and quantum mechanical properties of electromagnetic radiation 1.2 The electromagnetic spectrum 1.3 Energy states of chemical species 1.4 Interaction of radiation and matter (absorption, emission, scattering, luminescence) 1.5 Components of optical instruments 1.5.1 General design of optical instruments and basic function of main components in the instrument 9 SPECTROMETRIC METHODS A group of techniques that relies on the interaction of electromagnetic radiation and matter There are many type of methods that are based on either molecular or atomic interactions SPECTROSCOPIC TECHNIQUES Atomic -AAS -AES Molecular -UV/VIS -Luminescence -IR -Raman -NMR -Mass Spectroscopy  WHAT IS SPECTROSCOPY? The study of the interaction between ELECTROMAGNETIC (EM) RADIATION and MATTER SPECTROSCOPY ANALYSIS covers ATOMIC MOLECULAR SPECTROSCOPY SPECTROSCOPY (atomic absorption) (molecular absorption) 12  1.1 PROPERTIES OF ELECTROMAGNETIC RADIATION WHAT IS ELECTROMAGNETIC RADIATION? A form of energy that has both Wave and Particle properties. For example: Ultraviolet, visible, infrared, microwave, radio wave 13  (I) WAVE PROPERTIES EM radiation is conveniently modeled as waves consisting of perpendicularly oscillating electric and magnetic fields, as shown below. y x z Electric Field Magnetic Field Direction of propagation 14  WAVE PARAMETERS Period (p) The time required for one cycle to pass a fixed point in space. Frequency (ν @ f ) = 1/p the number of cycles which pass a fixed point in space per second. Unit in Hz or s-1 Amplitude (A) The maximum length of the electric vector in the wave (Maximum height of a wave). Wavelength (λ) The distance between two identical adjacent points in a wave (usually maxima or minima) 15  Wavenumber (ṽ) The reciprocal of the wavelength in the centimetres. The number of waves per cm in units of cm-1 Radiant Power ( P ) The amount of energy reaching a given area per second. Unit in watts (W) Intensity ( I ) The radiant power per unit solid angle. 16  Speed of light = Frequency x Wavelength c = ν c = 3.00 x 108 m/s c is the speed of light = 3.00 x 1010 cm/s ν is the frequency of the waves  is the wavelength of the waves In vacuum, the velocity of radiation is independent of wavelength and given by the symbol c In medium containing matter, light travel with velocity less than c The frequency of radiation is constant, the wavelength decrease 17  800 nm Infrared radiation Ultraviolet radiation V = 3.75 x 1014 s-1 V = 7.50 x 1014 s-1 Wavelength is inversely proportional to frequency 1  The higher the v, the shorter the λ & vice versa 18  (II) PARTICLE PROPERTIES EMR is viewed as a stream of discrete particles of energy called photons We can relate the energy, E of photon to its wavelength, frequency and wavenumber by, E = hν = = hcṽ h = Planck’s constant 6.63 x 10-34 Js Therefore wavenumber, ṽ ṽ = 1/ = ν/c Unit of wavenumber is cm-1 19  Example: Exercise: What is energy of a 500 nm What is the energy of a 530 nm photon? photon? ν = c/ ν = c/ = (3 x 108 m s-1)/(5.0 x 10-7 m) = (3 x 108 m s-1)/(5.3 x 10-7 m) = 6 x 1014 s-1 @ Hz = 5.66 x 1014 s-1 @ Hz E = hν E = hν = (6.626 x 10-34 J s)(6 x 1014 s-1) = (6.626 x 10-34 J s)(5.66 x 1014 s-1) = 4 x 10-19 J = 3.75 x 10-19 J 20  1.2 THE ELECTROMACNETIC SPECTRUM Region Wavelength Range γ-ray