INSTRUMENTAL ANALYSIS STUDY GUIDE QUESTIONS AND
SOLUTIONS 2025/2026 ALL GRADED A+
✔✔Diffraction of radiation - ✔✔diffraction: a parallel beam of radiation is bent when it
passes by a sharp barrier or through a narrow opening
✔✔coherent radiation - ✔✔radiation that is made up of wave trains having identical
frequencies or sets of frequencies and phase relationships that are constant with time.
✔✔refractive index - ✔✔ni=c/vi
✔✔transmission of radiation - ✔✔the passage of EM through a medium
dispersion: refractive index of a substance changes with frequency
✔✔refraction - ✔✔The bending of a wave as it passes at an angle from one medium to
another
snell's law: sinθ₁=n₂=v₁
⁻⁻⁻⁻⁻ ⁻⁻ ⁻⁻
sinθ₂=n₁=v₂
✔✔reflection - ✔✔Ir= (n₂-n₁)²
__ ________
Io (n₂+n₁)²
✔✔scattering - ✔✔certain radiation meets particles in its path and scattered in all
direction
✔✔Rayleigh scattering - ✔✔scattering of light caused by atmospheric particles smaller
than the wavelength being scattered
why we see a blue sky
d<<λ
✔✔Mie scattering - ✔✔scattering of light caused by atmospheric particles the same size
as the wavelength being scattered
-not wavelength dependent, white glare around the sun
✔✔unpolarized light - ✔✔assumed to consist of transverse waves vibrating in all
conceivable random directions
✔✔polarized light - ✔✔Light that has been filtered so that all of its waves are parallel to
each other
✔✔photoelectric effect - ✔✔The emission of electrons from a metal when light shines
on the metal
, ∆E=hv=hc/λ
✔✔Interaction of radiation with matter - ✔✔used to obtain info on a sample- stimulated
by heat, light
ground state- lowest energy
excited state- higher energy
✔✔emission - ✔✔excited particle relaxes to lower energy levels by giving up excess
energy as photons
✔✔absorption - ✔✔amount a sample absorbs light
✔✔luminescence - ✔✔emission of photons is measured after absorption
✔✔Inelastic Scattering - ✔✔Raman spectroscopy
vibration spectrum
✔✔Elastic Scattering - ✔✔same wavelength
✔✔relaxation - ✔✔molecules go back to ground state
✔✔convert radiation energy to electrical signal - ✔✔S=kP+kd
s=signal
k=constant
p=radiant power
kd= dark current
✔✔emission, luminescence and scattering method - ✔✔S=k' c
✔✔absorption method - ✔✔Beer's Law
A=∈bc
✔✔general design of radiation sources - ✔✔radiation source -> sample container ->
wavelength selector -> radiation transducer -> signal processor & readout
✔✔sample container - ✔✔transparent in spectral regions of interest
✔✔continuum sources - ✔✔extends over a wide range of wavelenghts
includes: UV, Vis, & IR
✔✔line sources - ✔✔localized at specific wavelengths
includes: metal vapor lamps & hollow cathode lamps
✔✔Laser source mechanism - ✔✔pumping-
SOLUTIONS 2025/2026 ALL GRADED A+
✔✔Diffraction of radiation - ✔✔diffraction: a parallel beam of radiation is bent when it
passes by a sharp barrier or through a narrow opening
✔✔coherent radiation - ✔✔radiation that is made up of wave trains having identical
frequencies or sets of frequencies and phase relationships that are constant with time.
✔✔refractive index - ✔✔ni=c/vi
✔✔transmission of radiation - ✔✔the passage of EM through a medium
dispersion: refractive index of a substance changes with frequency
✔✔refraction - ✔✔The bending of a wave as it passes at an angle from one medium to
another
snell's law: sinθ₁=n₂=v₁
⁻⁻⁻⁻⁻ ⁻⁻ ⁻⁻
sinθ₂=n₁=v₂
✔✔reflection - ✔✔Ir= (n₂-n₁)²
__ ________
Io (n₂+n₁)²
✔✔scattering - ✔✔certain radiation meets particles in its path and scattered in all
direction
✔✔Rayleigh scattering - ✔✔scattering of light caused by atmospheric particles smaller
than the wavelength being scattered
why we see a blue sky
d<<λ
✔✔Mie scattering - ✔✔scattering of light caused by atmospheric particles the same size
as the wavelength being scattered
-not wavelength dependent, white glare around the sun
✔✔unpolarized light - ✔✔assumed to consist of transverse waves vibrating in all
conceivable random directions
✔✔polarized light - ✔✔Light that has been filtered so that all of its waves are parallel to
each other
✔✔photoelectric effect - ✔✔The emission of electrons from a metal when light shines
on the metal
, ∆E=hv=hc/λ
✔✔Interaction of radiation with matter - ✔✔used to obtain info on a sample- stimulated
by heat, light
ground state- lowest energy
excited state- higher energy
✔✔emission - ✔✔excited particle relaxes to lower energy levels by giving up excess
energy as photons
✔✔absorption - ✔✔amount a sample absorbs light
✔✔luminescence - ✔✔emission of photons is measured after absorption
✔✔Inelastic Scattering - ✔✔Raman spectroscopy
vibration spectrum
✔✔Elastic Scattering - ✔✔same wavelength
✔✔relaxation - ✔✔molecules go back to ground state
✔✔convert radiation energy to electrical signal - ✔✔S=kP+kd
s=signal
k=constant
p=radiant power
kd= dark current
✔✔emission, luminescence and scattering method - ✔✔S=k' c
✔✔absorption method - ✔✔Beer's Law
A=∈bc
✔✔general design of radiation sources - ✔✔radiation source -> sample container ->
wavelength selector -> radiation transducer -> signal processor & readout
✔✔sample container - ✔✔transparent in spectral regions of interest
✔✔continuum sources - ✔✔extends over a wide range of wavelenghts
includes: UV, Vis, & IR
✔✔line sources - ✔✔localized at specific wavelengths
includes: metal vapor lamps & hollow cathode lamps
✔✔Laser source mechanism - ✔✔pumping-
