Fluorescence Spectroscopy

1
Fluorescence Spectroscopy Sheds Light on the
Who-Dunnit!
What are the Features of Light?
Why Do Molecules Glow, or Fluoresce?
Luminescence Spectroscopy
Fluorescence and Bioluminescence
The Electromagnetic Spectrum
Visible, White Light Dispersed
Features of Light

• The sample is hit by a wavelength of light
  i.e. BLUE (450 nm)
• The sample absorbs, or uses up, a small amount of
  this initial energy, and wants to spit-out the
  remaining as Fluorescence
• What remains is LESS energy so what is emitted
  as fluorescence is of LONGER wavelength i.e.
  GREEN (600 nm)
• Fluorescence 10-9 sec or 0.000000001 sec

Types of Luminescence

• Photoluminescence
• Fluorescence (10-9 sec)
• Phosphorescence (10-6 sec)
• Chemiluminescence
• Bioluminescence
• Electroluminescence
• Radioluminescence

• R - Red
• O - Orange
• Y - Yellow
• G - Green
• B - Blue
• I - Indigo
• V - Violet

VISIBLE
Wavelength (l) the length of 1 Cycle la or
lb Frequency (f) number of oscillations per
second Wave B has the Shorter Wavelength
Higher Frequency (and is the Stronger Wave)
High Energy
Low Energy
The Experiment How Did Our Friend Die?
The Technique The LS55 Fluorescence
Spectrometer
Schematic of the LS55 Fluorescence Spectrometer
We know that the Deceased Had a Thermos in his
Possession prior to his demise.We also know that
the Victim Loved his Bourbon

• Most bourbons are Aged Inside of Charred, burned
  Oak Barrels
• Burned Oak contains PolyAromatic Hydrocarbons
  (PAHs). These PAHs are transferred to the
  bourbon during Aging.
• The Color and Flavor of Bourbon are derived from
  this Burned Oak Aging.
• Trace amounts of these PAHs are dissolved in the
  bourbon these PAHs fluoresce in the Visible
  Region at 480 nm.

Fluorescence of Bourbon

• Antifreeze contains approximately 95 of Ethylene
  Glycol, which is the compound that is responsible
  for the cooling properties.
• Antifreeze also contains Fluorescein, which is
  the Aromatic Compound that provides the
  well-known Bright Green Color at 520 nm.
  Fluorescein is added so that a technician can
  easily diagnose a leak within the engines
  cooling system.
• If ingested by Humans, Ethylene Glycol, while not
  immediately toxic, is metabolized within the body
  to Glycoaldehyde, and later metabolized to
  Glycolic Acid, Glyoxylic acid, and Oxalic Acid.
• These three toxic metabolites cause Central
  Nervous System (CNS) Depression (i.e. drowsiness,
  and respiratory failure), followed by
  Cardiopulmonary Disorder, and later Renal Damage.
• The Lethal Dose of Ethylene Glycol, for an adult
  human, is 100 milliliters.

Fluorescence of Antifreeze
Our Conclusions
Using the LS55 Spectrometer, we are able to
identify the drink in the thermos as bourbon. We
are also able to identify antifreeze in the
victims drink, and have determined the amount
() of antifreeze present in the bourbon. The
results below indicate that the victims drink
contained almost 30 antifreeze. Assuming that
our victim had at least three drinks,
collectively this would contain more than the 100
mL Lethal Dose of Ethylene Glycol.
Is it Possible that Someone Spiked Our Friends
Beverage with a Lethal Dose of Poisonous
Antifreeze?If this were true, then the drink
would exhibit the typical green fluorescence,
most commonly known as Antifreeze Green, with an
emission at 520 nm. Further, bourbon would be
identified with fluorescence at 470 nm in the
emission spectrum.
Let Take a Look at the Contents of the Thermos,
and See if it Fluoresces
Victims Beverage