Lecture 05, 6

• What is spectroscopy?

  The study of matter and electromagnetic radiation
• What is spectrometry?

  A method for quantitative measurement of spectra
• What does atomic spectroscopy study?

  Electromagnetic radiation absorbed and emitted by atoms
• Why is it important to study atoms?

  • Essential elements can be toxic
  • Toxic metals are a re-circulating problem
  • Checking for contaminants in herbal materials
  • Impurities from pharmaceutical synthesis
  • Biological samples for metal overexposure
• What are the atomic instrumental methods mentioned?

  Atomic Absorption, Emission, Mass Spectrometry
• What are the interactions of radiation and matter?

  • Absorption
  • Emission
• What is the speed of light?

  Approximately $3 \times 10^8 \text{ m/s}$
• How does wavelength relate to energy?

  Shorter wavelength means higher energy
• What is the formula for energy of a photon?

  $E =$$h\nu =$$\frac{hc}{\lambda} =$$hc\nu$
• What are atomic transitions?

  Emission and absorption spectra consist of narrow peaks
• What state must atoms be in for atomic spectroscopy?

  Atoms must be in gaseous state
• What is the condition for absorption in atomic spectroscopy?

  Photon energy must match energy difference
• What is the process of atomic absorption spectroscopy?

  1. Atoms absorb radiation from a light source
  2. Generates a measurable signal proportional to concentration
  3. Requires longer path length for stronger signal
• What is the role of hollow cathode lamps in atomic absorption?

  Provide narrow bandwidth radiation for measurement
• What is nebulisation in atomic absorption?

  Creating an aerosol of liquid or solid particles
• What is atomisation in atomic absorption?

  Separation of particles into individual atoms
• What is chemical interference in atomic absorption?

  Components that decrease atomisation of analyte
• What are the differences between ICP-OES and ICP-MS?

  • ICP-OES measures light intensity; ICP-MS measures mass-to-charge ratio
  • ICP-OES has higher detection limits; ICP-MS has lower detection limits
  • ICP-OES is less expensive; ICP-MS is more expensive
  • ICP-OES is more susceptible to spectral interferences; ICP-MS is less susceptible
• What is the purpose of using a polychromator in ICP?

  To collect light at different wavelengths
• What is the significance of the plasma in ICP?

  It ionises argon gas at high temperatures
• What is the detection limit of ICP-MS?

  Low ppb to high ppt range
• What are practical considerations for atomic spectroscopy?

  • Acid wash glassware
  • Prepare low concentration standards daily
  • Digest solid samples with acid
  • Handle matrix effects carefully
• What is the main disadvantage of flame atomic absorption spectroscopy?

  95% of the sample goes to waste
• What is the role of releasing agents in chemical interference?

  They help improve atomisation of analytes
• What happens during the emission spectroscopy process?

  Light is emitted after absorption of energy
• What is the significance of emission spectra for elements?

  Each element has a unique spectrum
• What is the effect of temperature on Doppler and Pressure broadening?

  Both are more pronounced at higher temperatures
• What is the purpose of atomisation in atomic spectroscopy?

  To analyse elements in atomic state
• What is the main goal of atomic spectroscopy?

  To break molecules into atoms for analysis
• What is the significance of the emission line spectrum?

  It helps identify elements without overlap
• What is the role of the nebuliser in ICP-MS?

  It uses 1-2 ml per sample for analysis
• What is the main advantage of ICP-MS over FAAS?

  Superior detection capability for trace levels
• What is the purpose of acid digestion for solid samples?

  To prepare samples for analysis
• What is the significance of matrix effects in atomic spectroscopy?

  They can interfere with accurate measurements
• What is the main disadvantage of using FAAS?

  It cannot analyse multiple elements simultaneously
• What is the role of the monochromator in atomic spectroscopy?

  To disperse light for different wavelengths
• What is the significance of the unique spectrum of each element?

  It allows for identification of elements in samples
• What is the purpose of calibration curves in atomic spectroscopy?

  To relate signal intensity to concentration
• What is the effect of pressure broadening on atomic lines?

  It causes slight variations in ground-state energies
• What is the significance of the ground state in atomic absorption?

  It is the lowest energy level of an atom