Chemistry 1027A/B Lecture Notes - Transmittance, Wavenumber, Organic Compound
4 Nov 2013
School
Department
Course
Professor
Document Summary
Key concepts in organic chemistry: spectroscopic structural elucidation (usselman version) Energy is transmitted in the form of electromagnetic radiation understood as oscillating waves of electric and magnetic fields. Humans can detect radiation of wavelengths 400-800nm known as visible light. An average c-c bond absorbs uv light, bonds absorb visible light and the e for molecular conformations absorbs ir light. In ir spectroscopy, a chart of % transmittance of light through the sample beam against wavenumber (defined as the number of wavelengths in 12 cm) is produced. There are normally two regions in ir spectra investigated: the region from 4000-1400cm-1 (where absorptions are characteristic of several major functional groups) and the fingerprint region (1400- 400cm-1), which contains a complex absorption pattern dependent upon each specific molecular structure. Each of the functional group have characteristic absorption peaks . These peaks are identified by frequency (in wavenumbers) and intensity of absorption, whether weak (w), medium (m), or strong (s).
