spectroscopy

• James Maxwell - proposed that visible light consist of electromagnetic waves (1873)
• Isaac Newton - showed that visible light can be separated into different colors using a prism
• The Quantum theory states that energy can be gained or lost by matter in multiples of the quantity hv
• "Energy is quantized" according to Max Planck
• Photoelectric effect - light exists as stream of particles called photons
• Spectroscopy is the study of the interaction between electromagnetic radiation and matter
• Spectrometry - the measurement of electromagnetic radiation to obtain information about a system
• Emission spectroscopy - methods in which the stimulus for the analyte is the application of heat or electrical energy
• Emission Spectroscopy

  The radiant power emitted by the analyte as it returns to the ground gives information about its identity and concentration
• Chemiluminescence refers to excitation of the analyte by chemical reaction
• Line spectra occurs when the radiating species are individual atoms or ions in the gas phase
• Band spectra is produced due to presence of gaseous radicals or small molecules
• Continuous Spectra is produced when solids, such as tungsten, are heated to incandescence
• Absorption Spectroscopy

  The amount of light absorbed as a function of wavelength is measured which can give qualitative and quantitative information about the sample
• When UV or VIS radiation is passed through a medium containing gaseous atoms, the outermost electron of the atom is promoted from the ground state to higher energy level orbitals.
• Absorption spectra consist only of specific wavelengths that correspond to the energies of the electronic transitions between orbitals