仪器分析英文课件Chapter2-IntroductiontoSpectrometricMethods13.ppt

* * Chapter 2. An Introduction to Spectrometric Methods Spectroscopy (spectrometry): The study of the interaction between electromagnetic radiation (EMR) and matter. §1 General properties of electromagnetic radiation (EMR) ?What is EMR? - an oscillating (sinusoidal) electric and magnetic field which travels through space (Wave) - a discrete series of “particles” that possess a specific energy but have no mass (Particle) BOTH! §2 Wave properties of electromagnetic radiation EMR is conveniently represented as electric and magnetic fields that undergo in-phase, sinusoidal oscillations. Amplitude A- length of the electric vector at a maximum in the wave wavelength λ- linear distance between any two equivalent points on successive maxima (or minima) Period p – time for 1 l to pass fixed point Frequency ? - number of l passing per second Wavenumber n - number of l per cm Velocity v - distance point on wave travels per second v = n×l In a vacuum: vvacuum = c = 2.99792×108 m/s ? 3.00×108 m/s (“The Speed of Light”) Wave parameters Electromagnetic Spectrum EMR encompasses an enormous range of wavelengths and frequencies: Nuclear Spin in Magnetic field 1×10-3-1.7×10-2 0.6-10 m Nuclear Magnet Spin Electron Spin in Magnetic field 0.33 3 cm Electron Spin Resonance Molecule Rotation 13-27 0.75-3.75 mm Microwave Absorption Molecule Vibration (Rotation) 1.3×104 -3.3×102 0.78-300 μm Infrared Adsorption (Raman Scattering) Bonding Electron 5×104 -1.3×104 180-780 nm UV-VIS Absorption (Emission, Fluorescence) Bonding Electron 1×106 -5×104 10-180 nm Vacuum Ultraviolet Absorption Inner Electron - 0.1-100 ? X-Ray Absorption (Emission, Fluorescence, Diffraction) Nuclear Spin - 0.005-1.4 ? ?-Ray Emission Quantum Transfer Type Wavenumber (cm-1) Wavelength Spectroscopy EMR-based spectroscopy EMR phenomena (1) Absorption (2) Emission (3) Scattering (4) Refraction (5) Reflection (6) Interference (7) Diffraction