Spectroscopy

Description

Spectroscopy can be defined as the study of the interaction of electromagnetic radiation with matter, during which absorption, emission, or scattering of radiation may take place. The structure and chemical properties of a system can easily be understood and studied with the help of atomic and molecular spectroscopic techniques because there exists a fundamental relationship between the properties of a substance and the interaction of radiation with that substance. With the help of these techniques, molecular geometries, molecular symmetry, electronic distributions, electron densities, and electrical and magnetic properties of matter can be studied in detail. The importance of spectroscopy in the physical and chemical processes going on in planets, stars, and comets as well as in the interstellar medium has been continuously growing as a result of the use of satellites and the development of radiotelescopes for the microwave and millimeter wave regions. This book on spectroscopy gives a wealth of information that may be derived from spectra. It will be helpful for advanced graduate students in chemistry, chemical physics, or physics and also meet the need of industries. It is written in a very simple language so that it can easily be understood by everyone. Cover Half Title Title Page Copyright Page Table of Contents Preface Chapter 1: Introduction to Spectroscopy 1.1: Introduction 1.2: Interaction of Electromagnetic Radiation with Matter 1.2.1: Wave Properties of Electromagnetic Radiation 1.3: Electromagnetic Spectral Range 1.3.1: Radiofrequency Region 1.3.1.1: Microwave region 1.3.1.2: Infrared region 1.3.1.3: Visible and ultraviolet region 1.3.1.4: X-ray region 1.3.1.5: γ-ray region 1.4: Born–Oppenheimer Approximation 1.5: Energy Levels in Molecules and Quantization of Energy 1.6: Mechanism of Absorption and Emission 1.7: Transition Probability and Selection Rule 1.7.1: Transition Moment and Transition Moment Integral 1.7.2: Electronic Selection Rules 1.7.3: Vibrational Selection Rules 1.7.4: Rotational Selection Rules 1.8: Line Width and Line Shapes 1.8.1: Spectral Line Broadening and Line Shapes 1.8.2: Local Effects Broadening 1.8.3: Natural Line Broadening 1.8.4: Doppler Broadening 1.8.5: Pressure (Collision Broadening) 1.8.6: Broadening due to Inhomogeneous Local Effects 1.8.7: Broadening due to Non-local Effects 1.9: Fourier Transform Chapter 2: Nuclear Magnetic Resonance Spectroscopy 2.1: Introduction 2.2: Nature of Spinning Nucleus 2.3: Effect on the Nucleus of an External Magnetic Field 2.4: Precessional Motion of Nucleus 2.5: Precessional Frequency: Larmor Frequency 2.6: Energy Transitions and the Origin of NMR 2.7: Theory of NMR 2.7.1: Nuclear Spin and Magnetic Moment and Interaction Between Nuclear Spin and Magnetic Field 2.7.2: Population of Nuclear Energy Levels 2.7.3: Saturation and Relaxation 2.8: Concept of Chemical Shift 2.9: Types of Shielding 2.10: Factors Affecting Chemical Shift 2.10.1: Effect of Electronegativity (Inductive Effect) 2.10.2: Van der Waal’s Deshielding 2.10.3: Magnetic Anisotropy 2.10.3.1: Alkenes 2.10.3.2: Alkynes 2.10.3.3: Carbonyl compounds 2.10.3.4: Aromatic compounds 2.10.3.5: Effect of hydrogen bonding 2.10.3.6: Effect of solvents (types, concentration, temperature, and hydrogen bonding) 2.10.3.7: Solvents used in NMR 2.11: Spin–Spin Coupling 2.11.1: The Splitting of Signals in Proton NMR Spectra 2.11.2: Theory of Spin–Spin Coupling 2.12: The General Rule of Spin–Spin Splitting: The (n + 1) Splitting Rule 2.13: Complex NMR Spectra: Breakdown of (n + 1) Splitting Rule 2.13.1: Multiplicative Splitting 2.13.2: Non-first-order Spectra: Breakdown of the (n + 1) Rule 2.14: The Coupling Constant (J) 2.14.1: Factors Influencing Coupling Constant, J, and Various Types of Couplings 2.14.1.1: Geminal coupling 2.14.1.2: Vicinal coupling 2.14.1.3: Long-range proton–proton coupling 2.14.1.4: Heteronuclear coupling 2.14.1.5: 1H–13C spin–spin coupling 2.14.1.6: Deuterium coupling 2.15: Proton Exchange Reaction in NMR Spectrum of Alcohol 2.16: Restricted Rotation 2.17: Deuterium Exchange in NMR Spectroscopy 2.18: Simplification of Complexities of Proton NMR Spectra 2.18.1: By Increase in the Field Strength 2.18.2: By Spin Decoupling Method 2.18.3: By Using Chemical Shift Reagents 2.18.4: NMR of Nuclei Other Than Protons 2.18.4.1: 13C NMR 2.18.4.2: 19F NMR spectroscopy 2.18.4.3: 31P NMR 2.19: Instrumentation of NMR Spectroscopy 2.20: Nuclear Overhauser Effect 2.21: FT-NMR Chapter 3: Carbon-13: NMR 3.1: Introduction 3.2: Comparison with 1H NMR Spectroscopy 3.2.1: Characteristic Features of 13C NMR Spectra 3.2.2: Referencing 13C NMR Spectra 3.3: Instrumentation 3.4: Interpretation of 13C Spectra 3.4.1: Broadband Decoupling 3.4.2: Off-Resonance Decoupling 3.5: Chemical Shift 3.5.1: Origin 3.5.2: Scale 3.5.3: Effects on sp3: Carbons 3.5.4: α-Substituent Effects 3.5.5: Heavy-Atom α-Effect 3.5.6: α-Effect of Triple Bonds 3.5.7: α-Effect of Double Bonds 3.5.8: β-Substituent Effects 3.5.9: γ-Substituent Effects 3.5.10: δ-Substituent Effects 3.5.11: Membered Rings 3.5.12: Effects on sp2: and sp Carbons 3.5.13: Conjugation with π-Acceptors and π-Donors 3.5.14: Strongly Charged Systems 3.5.15: Carbonyl Groups 3.5.16: Conjugation Effects 3.5.17: Hydrogen Bond Effects 3.6: Application of 13C NMR 3.6.1: Identification of Molecules 3.6.2: Soil Organic Matter Studies 3.6.3: Physical Separations and Structural Characterization of Organic C in Bulk Soils Chapter 4: Electron Spin Resonance Spectroscopy 4.1: Introduction 4.2: Basic Principles and Origin of ESR Spectra 4.3: The Electron g-Factor 4.3.1: Factor Affecting g-Factor 4.3.2: Determination of g-Values 4.4: Saturation and Relaxation in ESR Spectroscopy 4.4.1: Spin–Lattice Relaxation Process 4.4.2: Spin–Spin Relaxation Process 4.5: Splitting of ESR Signals: Hyperfine Interaction 4.6: Zero-Field Splitting: Kramer Degeneracy 4.7: Isotropic Coupling Constant 4.7.1: Isotropic Hyperfine Splitting from Single Set of Equivalent Protons 4.7.2: Isotropic Hyperfine Splitting from Multiple Set of Equivalent Protons 4.8: Anisotropy and Hyperfine Splitting 4.8.1: Anisotropy in Crystals 4.8.1.1: Cubic system 4.8.1.2: Uniaxial symmetry 4.8.1.3: Rhombic symmetry 4.9: Instrumentation 4.9.1: Source 4.9.1.1: Microwave oscillator 4.9.1.2: Wave guide and wave meter 4.9.1.3: Attenuator 4.9.1.4: Isolator 4.9.2: Sample Cell/Cavity 4.9.3: A Magnet System 4.9.4: Detector 4.9.5: Recorder 4.9.5.1: Working of instrument 4.10: Application of ESR Spectroscopy Chapter 5: Infrared Spectroscopy 5.1: Introduction 5.2: Principle of Infrared Spectroscopy 5.3: The Vibration in a Diatomic Molecule 5.3.1: Zero-Point Energy 5.3.2: Infrared Spectra and Selection Rule 5.3.3: Limitations and Drawbacks of Simple Harmonic Oscillator Model 5.4: The Diatomic Molecules as Anharmonic Oscillator 5.4.1: Zero-Point Energy for Anharmonic Oscillator 5.4.2: Infrared Spectra and the Selection Rule 5.4.3: Hot Bands 5.5: The Vibrating Rotating Diatomic Molecule (Vibrational–Rotational Spectra) 5.5.1: Energy Levels of Rotating Vibrators 5.5.1.1: Case I: Diatomic molecules performing harmonic oscillations and behaving as a rigid rotator 5.5.1.2: Case II: Diatomic molecules performing anharmonic oscillation and behaving as non-rigid rotators 5.6: Vibration and Rotation Spectra of Polyatomic Molecule 5.6.1: Number of Fundamental Vibrations and Their Symmetry in a Polyatomic Molecule 5.6.1.1: Normal modes of vibrations in polyatomic molecules 5.6.2: The Influence of Rotation on the Spectra of Polyatomic Molecules 5.6.2.1: Linear molecules with parallel vibrations 5.6.2.2: Linear molecules with perpendicular vibrations 5.6.2.3: Symmetric top molecules with parallel vibrations 5.6.2.4: Symmetric top molecules with perpendicular vibrations 5.7: Factor Affecting the Infrared Absorption 5.7.1: Effect of Force Constant, Bond Strength, and Isotopic Substitution 5.7.2: Electronic Effects 5.7.2.1: Mesomeric effect 5.7.2.2: Inductive effect 5.7.3: Bond Angles Effect 5.7.4: Effect of Hydrogen Bonding 5.7.4.1: Intramolecular hydrogen bonding 5.8: Application and Analysis by Infrared Spectra 5.8.1: Structural Analysis 5.9: The Infrared Spectrometer: Instrumentation and Technique 5.9.1: Infrared Light Sources 5.9.2: Monochromator 5.9.3: Detectors 5.9.4: Dispersive IR Spectrometer 5.10: Drawback of Double Beam Dispersive Spectrometer 5.11: Fourier Transform Infrared Spectrometer 5.11.1: Basic Principle and Operation of FTIR Fourier Transform Infrared Spectroscopy 5.11.2: Advantages of FTIR Chapter 6: Microwave Spectroscopy 6.1: Introduction 6.2: Rotational Spectra of Linear Diatomic Molecule 6.2.1: The Rigid Linear Diatomic Molecule 6.2.2: Description of Rotational Spectra of Rigid Rotating Diatomic Molecule 6.3: Various Transitions in the Rotational Spectrum 6.4: The Selection Rule 6.5: Intensities of Rotational Spectral Lines 6.6: Isotopic Substitution 6.7: Techniques and Instrumentation 6.7.1: The Source and Monochromator 6.7.2: Waveguide 6.7.3: Sample and Sample Space 6.7.4: Detector 6.7.5: Spectrum Recorder 6.8: Applications of Microwave Spectroscopy Chapter 7: Raman Spectroscopy 7.1: Introduction 7.2: Quantum Mechanical Concept of Raman Effect 7.3: Molecular Polarizability and the Raman Effect 7.4: Rotational Raman Spectra 7.5: Vibrational Raman Spectra 7.6: Rotational–Vibrational Raman Spectra 7.7: Instrumentation 7.7.1: Light (Radiation Source) 7.7.2: A Sample Illumination and Light Collection Optic System 7.7.3: Detectors and Data Recording System 7.8: Comparison Between IR and Raman Spectroscopic Techniques Chapter 8: Electronic Spectroscopy 8.1: Introduction 8.2: The Nature of Electronic Excitations 8.2.1: σ → σ* Electronic Transition 8.2.2: n → σ* Electronic Transition 8.2.3: п → п * Transition 8.2.4: n → п* Transition 8.3: Selection Rule for the Electronic Transition 8.4: Beer–Lambert Law 8.5: Chromophore and Auxochrome 8.6: Effect of Solvent on Electronic Transition (Solvent Effect) 8.7: Effect of Conjugation 8.8: Woodward–Fisher Rule 8.8.1: For Dienes 8.8.2: For Carbonyl Compounds: Enones 8.8.3: Woodward Rule for Enone System 8.8.4: Woodward’s Rule for α, β-Unsaturated Aldehydes, Acids, and Esters 8.9: Absorption in Aromatic Compounds 8.10: Color in Transition Metal Complex 8.11: Charge Transfer Transition 8.11.1: Ligand to Metal Charge Transfer 8.11.2: Metal to Ligand Charge Transfer Chapter 9: Fluorescence and Phosphorescence Spectroscopy 9.1: Introduction 9.2: Principle of Fluorescence and Phosphorescence 9.2.1: Rules Governing Fluorescence 9.2.1.1: Kasha’s rule 9.2.1.2: Frank–Condon (FC) principle 9.3: Instrumentation 9.4: General Properties of Fluorescence and Phosphorescence 9.4.1: Fluorescence 9.4.2: Phosphorescence 9.5: Fluorescence Parameters 9.5.1: Fluorescence Emission Spectra (λex: Fixed) 9.5.1.1: Stokes’s shift 9.6: Fluorescence Excitation Spectra [Wavelength of Emission (λem): Fixed] 9.7: Fluorescence Quantum Yield 9.8: Fluorescence Lifetime 9.9: Synchronous Fluorescence Spectroscopy 9.10: Fluorescence and Structure 9.11: Fluorescence and Temperature 9.12: Intrinsic and Extrinsic Fluorophores 9.13: Applications 9.14: Fluorophores: Intrinsic 9.14.1: Concentration Determination 9.14.2: Study of Excited State Properties 9.14.3: Excited State Acidity Constants 9.14.3.1: Forster cycle method: Theoretical 9.14.3.2: Fluorimetric titration method (pH dependence of fluorescence 9.15: Solvotochromic Shifts 9.16: Fluorescence Quenching 9.17: Synchronous Fluorescence Spectroscopy Applications 9.18: Phosphorescence Spectroscopy 9.19: Conclusions Chapter 10: X-ray Fluorescence and Its Applications for Materials Characterization 10.1: Introduction 10.2: Production of X-rays 10.3: Interaction of X-rays with Matter 10.4: Characteristic X-rays 10.5: X-ray Fluorescence Principle 10.5.1: X-ray Fluorescence Analysis 10.6: Instrumentation and Geometrical Consideration 10.7: Application of XRF in Materials Characterization 10.7.1: Some Examples of XRF Application in Different Areas of Science and Technology 10.8: Advancements in XRF Analysis Index