IA MOCK EXAM

• According to the classical electromagnetic theory of radiation, radiation is a wave where:

  Electric and magnetic fields are oscillating in time and are mutually perpendicular. Propagation direction is perpendicular to both the electric and magnetic field.
• How can the relation between wavelength, frequency and light speed can be written as: 


  c=λ⋅ν or c/λ=ν
• According to the different models, light intensity is:

  Related to the number of photons (and to the energy of each photon) in the light beam (quantum theory) and directly proportional to the square of the electric field (classical theory)
• An atom consist of:

  A positively charged nucleus surrounded by negatively charged electrons. In the nucleus, there are positive particles called protons, neutral particles called neutrons.
• How can we describe an element (or elemental substance) in chemistry?

  A substance having all atoms with the same atomic number, Z.
• The De Broglie equations states that:

  • p=h/λ
  • where p is the momentum
  • and λ is the wavelength
• De Broglie relationship applies:

  to any particle, it does not matter the size
• A=−log10(T)

  Labert-Beer Law
• A=−log10(T)


  Is the relationship between absorbance and transmittance
• From high to lower energy quantum levels:

  1. Electronic levels
  2. Vibrational levels
  3. Rotational levels
• What is a transmittance instrument?

  A polychromatic light beam is sent through a thin layer of a sample, or a solution of the sample: the radiation in output from the sample is separated in different monochromatic components, and each component is detected and quantified
• Classify the spectroscopies according to the spectroscopic event:

  Absorption, emission, scattering spectrocopies
• In an IR spectrum are normally reported:


  Transmittance/absorbance on the y axis, wavenumber (in cm-1) on the x axis
• In the IR spectrum, the fingerprint region is:

  The region between 400 and 1500 cm-1, characterized by many bands/peaks useful to identify precisely the molecule inside a class of molecules.
• In CH, IR spectroscopy is specifically useful for:

  Organic compounds, like binders, varnishes, plastic coatings, etc.
• The light source used in Raman is:

  A laser in the UV-vis-NIR range.
• Raman spectroscopy can be used:

  Both for organic and inorganic compounds
• The event, in which the XRF spectroscopy is based on is:

  Absorption of an X-ray photon by an atom, with expulsion of an inner electron and emission of X.ray radiation
• We can classify XRF spectroscopy as:

  An atomic, emission spectroscopy
• From the XRF spectroscopy we can have information on:

  The elemental composition of the sample (i.e., the type of elements present) and their relative abundance. However, only atoms with Z higher than Na can be detected.
• In the ED-XRF spectrum, the detector:

  Is a Geiger counter or solid-state device. It provides an electric pulse proportional to the energy of the incoming X-ray photon.
• The use of XRF is subjected to specific authorizations because of the potential risks of X-ray radiation to human health.