The Spectroscopy reference article from the English Wikipedia on 24-Apr-2004 (provided by Fixed Reference: snapshots of Wikipedia from wikipedia.org)

Spectroscopy

In physics, spectroscopy is the study of spectra.

A device for recording a spectrum is a spectrometer.

Spectroscopy can be classified according to the physical quantity which is measured or calculated or the measurement process.

Physical quantity measured

The type of spectroscopy depends on the physical quantity measured. Normally, the quantity that is measured is an amount or intensity of something.

• The intensity of emmitted electromagnetic radiation and the amount of absorbed electromagnetic radiation is studied by electromagnetic spectroscopy.
• The amplitude of a macroscopic vibrations are studied by acoustic spectroscopy, and dynamic mechanical spectroscopy.
• Kinetic energy of particles is studied by electron energy loss spectroscopy, Auger electron spectroscopy
• The mass-to-charge ratio of molecules and atoms are studied in mass spectrometry. Note that a mass spectrometer does not measure the kinetic energy of particles: all particles have the same known kinetic energy (or an integer multiple thereof, depending on the charge). It is disputable whether this field strictly is a type of spectroscopy.
• The number of molecules or atoms or quantum-mechanical states to which the frequency or energy parameter applies.

Measurement process

Different types of spectroscopy use different measurement processes:

• Fourier transform is an efficient method for collecting various spectra. The use of Fourier transform in spectroscopy is called Fourier transform spectroscopy. It is frequently applied to infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) spectroscopy.
• Spectroscopy involving the bombarding a sample maintained under under ultra high vacuum with X-rays is called X-ray photoelectron spectroscopy.
• Spectroscopy of matter in situations where the properties are changing with time is called Time-resolved spectroscopy.
• Spectroscopy using an AFM-based analytical technique is called Force spectroscopy.
• Dielectric spectroscopy
• Measuring the rotations of molecules is called rotational spectroscopy.
• Measuring the vibrations of molecules is called vibrational spectroscopy.

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