6: An Introduction to Spectrophotometric Methods
- Page ID
- 333359
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- 6.1: General Properties of Electromagnetic Radiation
- Electromagnetic radiation—light—is a form of energy whose behavior is described by the properties of both waves and particles. Some properties of electromagnetic radiation, such as its refraction when it passes from one medium to another, are explained best when we describe light as a wave. Other properties, such as absorption and emission, are better described by treating light as a particle.
- 6.2: Wave Properties of Electromagnetic Radiation
- Electromagnetic radiation consists of oscillating electric and magnetic fields that propagate through space along a linear path and with a constant velocity. The oscillations in the electric field and the magnetic field are perpendicular to each other and to the direction of the wave’s propagation. In this section we consider the wave model of electromagnetic radiation.
- 6.3: Quantum Mechanical Properties of Electromagnetic Radiation
- In the last section, we considered properties of electromagnetic radiation that are consistent with identifying light as a wave. Other properties of light, however, cannot be explained by a model that treats it as a wave; instead, we need to consider a model that treats light as a system of discrete particles, which we call photons.
- 6.4: Emission and Absorbance Spectra
- When an atom, ion, or molecule absorbs a photon it undergoes a transition from a lower-energy state to a higher-energy, or excited state, we obtain an absorbance spectrum. The result of the reverse process, in which an atom, ion, or molecule emits a photon as it moves from a higher-energy state to a lower energy state, is an emission spectrum. In this section we consider the characteristics of each.
- 6.5: Quantitative Considerations
- An important part of the chapters that follow is a consideration of how we can use the emission or absorbance of photons to determine the concentration of an analyte in a sample. Here we provide a brief summary of quantitative spectroscopic methods of analysis, leaving more specific details for later chapters.