anachem II spectroscopy

• Spectroscopy

  ➢Interaction of radiation and matter
• Spectroscopy

  ➢powerful tool for qualitative and quantitative

  analysis
• Spectroscopy

  ➢include studies with other types of

  electromagnetic radiation (emr) such as x-ray,

  ultraviolet, infrared, microwave, and

  radiofrequency radiation
• Electromagnetic radiation (emr)

  ➢ Form of energy transmitted through space at

  enormous velocities

  ➢ Can be treated as discrete packets of energy or

  particles (photon or quanta)

  ➢ Has both particle and wave properties
• fill in the blanks

  A) cm

  B) 3.00

  C) 8

  D) 6.63 x 10

  
• fillll

  A) x rays

  B) IR

  C) radio

  D) visible

  E) uv

  
• Optical methods

  • spectroscopic methods based upon

  ultraviolet, visible, and infrared

  radiation
• fill

  A) 0.1

  B) 200

  C) 800

  D) 50

  
• filll

  A)

  B) 0.14

  C) 0.01

  D) 380

  E) 780

  F) nuclear emmision

  G) nuclear absoprtion

  
• • Absorption

  • A process in which a chemical species in a

  transparent medium selectively attenuates

  (decreases the intensity of) certain

  frequencies of electromagnetic radiation
• Po = incident radiation

  P = transmitted radiation

  b = path length in cm
• fill the missing formulas

  A) P/Po

  B) -log T

  C) log P/Po

  
• Molecular absorption in the ultraviolet and visible

  regions consists of absorption bands made up of closely

  spaced lines. The typical absorption band consists of a

  multitude of lines.
• Beer’s Law

  For monochromatic radiation, absorbance is directly

  proportional to the path length b through the medium

  and the concentration c of the absorbing species.]
• A = abc

  A = εbc

  A = Absorbance

  a = absorptivity

  b = pathlength in cm

  c = concentration

  ε = molar absorptivity
• Real Limitations

  • encountered only in relatively concentrated

  solutions; refractive index may change with

  concentration, hence changing molar absorptivity
• At high concentrations (usually > 0.01M), the average

  distance between the species responsible for absorption is

  diminished to the point where each affects the charge

  distribution of its neighbors, hence, their ability to absorb

  a given wavelength of radiation is altered.
• Fourier Transform InfraRed (FT-IR)