Please note the direction of the horizontal axis (wavenumber) in IR spectra decrease from left to right. The wavenumber is defined as the reciprocal of wavelength ( Formula 6.3), and the wavenumbers of infrared radiation are normally in the range of 4000 cm -1 to 600 cm -1 (approximate corresponds the wavelength range of 2.5 μm to 17 μm of IR radiation). But instead of using frequency to show the absorbed radiation, wavenumbers (, in unit of cm -1) are used as a conventional way in IR spectra. The horizontal axis indicates the position of an absorption band.A molecule have a variety of covalent bonds, and each bond have different vibration modes, so the IR spectrum of a compound usually show multiple absorption bands. The spikes are called absorption bands in an IR spectrum. Lower values of % transmittance mean that some of the energy is absorbed by the compound, and gives the downward spikes. At the high end of the axis, 100% transmittance means no absorption occurred at that frequency. The solid line traces the values of % transmittance for every wavelength passed through the sample. The vertical axis is ‘% transmittance’, which tells how strongly light was absorbed at each frequency.With the basic understanding of the IR theory, we will take a look at the actual output from IR spectroscopy experiments, and learn how to get structural information from IR spectrum. Below is the IR spectrum for 2-hexanone. Graphical Plot of % Transmittance vs.6.3 IR Spectrum and Characteristic Absorption Bands.Fragment Peaks (Fragment Ions) and Isotope Peaks (Isotope Ions)ġ1-5 - Review of Electromagnetic Radiation (“light”).Fragmentation into Smaller Radicals and Cations.SECTION 11 - Mass Spectrometry and IR Spectroscopy Mass Spectrometry and IR Spectroscopy - Section 11 of Organic Chemistry Notes is 9 pages in length (page 11-1 through page 11-9) and covers ALL you'll need to know on the following lecture/book topics: 3 - Chemical Quantities and StoichiometryĤ - Types of Chemical Reactions and Solution Stoichiometryħ - Quantum Mechanical View of the Atom, and Periodicityĩ - Covalent Bonding and Molecular Orbitalsġ0 - Liquids, Solids, and Intermolecular Forcesġ5 - Applications of Acid-Base Equilibriaġ6 - Spontaneity, Entropy, and Free Energyġ8 - Transition Metals and Coordination ChemistryĢ0 - An Introduction to Organic Chemistryġ - Structural, Bonding, Molecular PropertiesĢ - The Nature of Organic Compounds: Alkanes and Cycloalkanesģ - Stereochemistry of Alkanes and Cycloalkanes: 3-D Structures of MoleculesĤ - The Study of Organic Reactions: An Overviewġ0 - Substitution (SN2, SN1) and Elimination (E2, E1) Reactionsġ1 - Mass Spectrometry and IR Spectroscopyġ3 - Conjugated Systems and UV Spectroscopyġ5 - Electrophilic Aromatic Substitution (E.A.S.)ġ8 - Aldehydes and Ketones: Nucleophilic Addition ReactionsĢ0 - Carboxylic Acid Derivatives and Nucleophilic Acyl Substitution ReactionsĢ1 - Carbonyl Alpha-Substitution Reactions

Organic chemistry ir spectroscopy chart