What is a Wave?

Feb 14, 2017 | Glossary of Spectroscopy Terms, Properties of Light

A wave is an oscillation in energy. In the context of electromagnetic radiation, the electric and magnetic fields oscillate. These oscillations repeat a pattern. For example, think of a sine wave. It starts at zero, goes up to a crest, goes down to a trough, and comes...

What is a Photon?

Feb 14, 2017 | Glossary of Spectroscopy Terms, Properties of Light

A photon is a quantized amount of electromagnetic radiation that behaves like a particle. Each photon has a frequency, ν ,and a wavelength, λ. The energy of a photon is E=hν where h is Planck’s constant. On diagrams, they will often be represented as a wave...

What is Absorption and Emission?

Feb 14, 2017 | Glossary of Spectroscopy Terms, Properties of Light

Absorption is a process where an atom or molecule absorbs energy to promote an electron into a higher energy level. Often, the energy is delivered by a photon. The photon must have the same energy as the difference between the energy levels in the atom or molecule....

What is Coherence?

Feb 14, 2017 | Glossary of Spectroscopy Terms, Lasers

Coherence describes how the relative phases of waves behave. If the relative phase is constant, the waves are said to be coherent. If the relative phase changes, the waves are said to be incoherent. When talking about distance, it is called spacial coherence....

What is a Laser?

Feb 14, 2017 | Glossary of Spectroscopy Terms, Lasers, Light Source

The word “laser” is an acronym that stands for “light amplification by stimulated emission of radiation.” Lasers have two main components: a cavity made by two mirrors that reflect light between them and a gain medium that sits inside the cavity. Energy is pumped into...