Far IR-Region 15 – 200 micron Overtone or harmonic 5.33 Lecture Notes: Introduction to Spectroscopy Page 2 1 What does a spectrum measure? Method involves: (1) excitation and (2) detection. It is measured in Hz, where 1 Hz = 1 cycle/sec. • a molecule can have both IR and Raman signals at the same frequency, though if the Raman signal is strong, the corresponding IR … one another. Lecture Notes Chem 524 – IR spectra (Part 16)- 2013 For HTML of 2005 notes, click here XII. Near IR-Region 0.8 – 2.5 micron Rotational Spec. Part 2: Introduction to Molecular Spectroscopy: An introduction to the different types of molecular spectroscopic analysis, including UV-Vis, fluorescence, IR, MS and NMR, describing the basic principles of each technique and practical considerations including sample preparation. light having a longer wavelength and a lower frequency than visible light. The basic idea: Light (E.M. wave) In most spectroscopies, we characterize how a sample modifies light entering it. often quite strong in IR spectroscopy. Infrared Spectroscopy generally refers to the analysis of the interaction of a molecule with infrared light. Infrared Spectroscopy — focus on vibrational transitions (Read Chap 14) A. Wavelength, λ (lambda), is the Infra Red Spectroscopy Introduction: The absorption of infra-red radiations causes the various bands in a molecule to stretch or bend w.r.t. Resources: IR and Raman Spectroscopy overview Powerpoint- FT-IR. The portion of the infrared region most useful for analysis of organic compounds have a wavelength range from 2,500 to 16,000 nm, with a corresponding frequency range from 1.9*1013 to 1.2*1014 Hz. Mid infra red region 2.5 – 1.5 micron Vib-Roto Spec. IR spectroscopy (which is short for infrared spectroscopy) deals with the infrared region of the electromagnetic spectrum, i.e. Why Raman spectroscopy? Electromagnetic radiation is a simple harmonic wave of electric and magnetic fields fluctuating orthogonal to each other (Figure 3.1A). Regions: -- near IR (800-2500 nm — quartz optics/W-I lamp, diode or thermal detect) anharmonic vib, overtone and combination bands. • Information on rotational and vibrational levels • Raman effect small but accessible by use of lasers • Complementary information to IR spectroscopy phomonuclear diatomic molecules, low frequency range • In situ analysis of organic and inorganic compounds • Analysis of aqueous solutions and solids (powders) Spectroscopy deals with the study of interaction of electromagnetic radiation with matter. Interaction of light with a sample can influence the sample and/or the light. Frequency, ν (nu), is the number of wave cycles that pass through a point in one second. Return to this later, specific use Spectroscopy: an Historic Journey (pre-history) Overview This course is targeted to advanced level undergraduate students (Bolonha 2th cycle) in Chemistry, Physics or Bio-Sciences and Freshmen PhD Students aiming to get a general overview of molecular spectroscopy. INFRARED SPECTROSCOPY (IR) Theory and Interpretation of IR spectra ASSIGNED READINGS • Introduction to technique 25 (p. 833-834 in lab textbook) • Uses of the Infrared Spectrum (p. 847-853) • Look over pages 853-866 after viewing this presentation for additional examples of various functional groups. • bending vibrational modes lead to much weaker Raman signals and are often quite strong in IR spectroscopy. Infrared refers to that part of the electromagnetic spectrum between the visible and microwave regions. Lecture 3 Basics of Spectroscopy . Infrared Spectroscopy is the analysis of infrared light interacting with a molecule. 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