各种仪器分析的基本原理及谱图表示方法（The basic principle of instrument analysis and spectral representation method）.docVIP

各种仪器分析的基本原理及谱图表示方法（The basic principle of instrument analysis and spectral representation method） Ultraviolet absorption spectrum UV The principle of analysis: the absorption of ultraviolet light energy causes the transition of the electronic energy levels in molecules Spectral representation: the relative absorption of light energy varies with the wavelength of absorption light Information provided: the position, intensity, and shape of the absorption peaks, providing information about the different electronic structures of the molecules Fluorescence spectrometry, FS Analysis principle: excited by electromagnetic radiation, from the lowest singlet excited state back to the ground state of single line, emission fluorescence Spectral representation: the emission of fluorescence energy varies with the wavelength of light Information available: fluorescence efficiency and lifetime, providing information on the different electronic structures of molecules Infrared absorption spectroscopy IR The principle of analysis: the absorption of infrared energy leads to vibrational and rotational energy levels transition of molecules with dipole moments Spectral representation: the relative transmission light energy varies with the transmission light frequency Information provided: the position, intensity, and shape of the peaks, providing characteristic vibrational frequencies of functional clusters or chemical bonds Raman spectroscopy, Ram Analysis principle: after absorbing light energy, it can cause molecular vibration with polarization change and produce Raman scattering Spectral representation: the variation of scattered light energy with Raman shift Information provided: the position, intensity, and shape of the peaks, providing characteristic vibrational frequencies of functional clusters or chemical bonds Nuclear magnetic resonance spectroscopy, NMR Analysis principle: in an external magnetic field, an atom with a nuclear magnetic moment absorbs the radio frequency energy