Colorimetry, Light, Electromagnetic Waves, Electromagnetic Radiations

Modern Analytical Chemistry

1. Colorimetry?

•Each chemicals substances/componuds (gas/solutions/solids) have characteristic colors(Chroma).

•The intensity of such a color is proportional to the concentration of the substances/ compounds

Internal Energy of Molecules

Etotal=Etrans+Eelec+Evib+Erot+Enucl

Eelec = Electronic transitions (UV, X-ray)

Evib  = Vibrational transitions (Infrared)

Erot  = Rotational transitions (Microwave)

Enucl= Nucleus spin (NMR: Nuclear Magnetic  Resonance)

  or (MRI: Magnetic Resonance Imaging)

2. Light?

Light is a special type of wave

What we know as light or VISIBLE LIGHT is actually a type of something called ELECTROMAGNETIC SPECTRUM (ES).

ES:

–Electromagnetic Wave (EW)

–Electromagnetic Radiation (ER)

3. Electromagnetic Waves

When something creates energy it also emits radiation.  Depending on the amount of energy, the object will emit different types of electromagnetic radiation.

When we studied mechanical waves, they were all transferred through a medium.  What medium is light transferred through?

LIGHT DOES NOT NEED ONE!

4. Electromagnetic Radiations

Electromagnetic waves are special in the fact that they do not need a medium to propagate through.

But what is creating the disturbance?  What is emitting this energy?

ELECTRONS

Electrons in materials are vibrated and emit energy in the form of photons, which propagate across the universe.

Photons have no mass, but are pure energy.

Electromagnetic Waves are waves that are made up of these “photons”.

When these photons come in contact with boundaries, E-M waves interact like other waves would.