Module 15

• The interactions of radiation and matter are the subject of the science.

  Spectroscopy
• What is the largest and most important group of techniques used in analytical chemistry?

  Spectrometric techniques
• All spectrometric techniques depend on the emission or absorption of?

  Electromagnetic radiation
• Form of energy that is transmitted throught space at enormous velocities.

  Electromagnetic radiation
• Electromagnetic radiatiom can be described as a wave with properties of?

  Wavelength, Frequency, Velocity, and Amplitude
• Electromagnetic radiation can be treated as discrete packets of energy or particles called:

  Photons or quanta
• The energy of a photon is directly proportional to its frequency.
• PLANCK’S formula

  E=hv

  E - is the energy of a photon in Joules

  h - constant (6.625x10^-34 erg secs)

  v - frequency
• The number of complete cycles or oscillations per second.

  Frequency
• The linear distance between any two equivalent points in successive cycle.

  Wavelength
• Is transmitted via electromagnetic waves that are characterized by their frequency and wavelenght.

  Energy
• Number of vibration of wave motion per second.

  Frequency
• The entrire distribution of electromagnetic radiation according to frequency or wavelenght.

  Electromagnetic Spectrum
• The maximum value reached by the vector in a cycle.

  Amplitude
• Is the time in seconds for successive maxima or minima to pass a point in space.

  Period
• The unit of frequency, which corresponds to one cycle per second.

  Hertz (Hz)
• 1 Hz is equal to?

  1s^-1
• The frequency of a beam of electron radiation DOES NOT CHANGE as it passes through the different media
• Is the linear distance between successive maxima or minima of a wave.

  Wavelength
• Measures the extent of interaction between electromagnetic radiation and the medium through which it passes.

  Refractive Index
• It is the most often used to describe radiation in the infrared region.

  Wavenumber
• The most useful part of the infrared spectrum for the detection and determination of organic species is from 2.5 to 15 μm.

  Wavenumber
• Is a particle of electromagnetic radiation having zero mass and an energy of hv.

  Photon
• Of the spectrum extends from about 400 nm to almost 800 nm.

  Visible region
• Are spectroscopic methods based on ultraviolet, visible, and infrared region.

  Optical methods
• Literally multicolored light, is light of mant wavelengths, such as that from a tungsten light bulb.

  Polychromatic light
• Commonly called stray light.

  Stray radiation
• Defined from the instrument that is outside nominal wavelength band chosen for the determination.

  Stray radiation
• Electromagnetic radiation that is unwanted and interferes with the performance of optical system.

  Stray light
• Travels millions faster than sound waves.

  Light waves
• Used to check the accuracy of the wavelenght.

  Didymium or Holmium Oxide filter
• • UV region: <400 nm
  • Infrared radiation: >700 nm
  • Visible light: 400-700 nm
• Refers to excitation of the analyte by a chemical reaction.

  Chemiluminescence Spectroscopy
• Usually refers to methods in which stimulus is heat or electrical energy.

  Emission Spectroscopy
• A plot of the emitted radiation as a function of frequency or wavelength.

  Spectrum
• A familiar example of chemiluminescence is found in the light emitted by a FIREFLY.

  Luciferin + ATP ————->(luciferase) Oxyluciferin + CO2 + AMP (adenosine monophosphate)
• Chemiluminescence involving a biological or enzyme reaction is often termed:

  BIOLUMINESCENCE
• The sample is excited by applying thermal, electrical, or chemical energy. No radiant energy is used to produce excited states, and so, these are called non-radiative processes.

  Emission or chemiluminescence processes
• Radiation of incident radiant power P

  can be absorbed by the analyte, resulting in a transmitted beam of lower radiant power P.

  Absorption methods
• Fluorescence and phosphorescence result from absorption of electromagnetic radiation and then dissipation of the energy by emission of radiation

  Photoluminescence methods