CHMA10H3 Lecture Notes - Lecture 8: Microsoft Onenote, Photon, Nicotine
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CHMA10H3 Full Course Notes
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Absorption spectrum: a plot of radiation energy vs. the percentage of radiation transmitted back from a compound. Wavelength: the distance between two successive wave maxima. Frequency (v): refers to the number of peaks that pass by a fixed point per unit time. Amplitude: is the height of the wave measured from the centre. When a molecular substance is irradiated with electromagnetic radiation, energy is absorbed if it matches the energy of a vibrational mode of its molecules. Vibrational mode: can be visualized as stretching and twisting of bonds in specific situations. The absorbed energy is characteristic for various functional groups. Ir photons have the necessary energy to excite vibrations within molecules. Things that are very heavy tend to vibrate at a low energy. Particular vibrations require and ir photon of specific energy (wavelength) In the infrared absorption spectrum, instead of wavelengths (measured in time) there are wavenumbers (measured in space) which equal to 1/wavelength(cm)
