UV-Vis Flashcards
What is wavelength usually measured in?
nm
What are UV and Visible light?
Part of the electromegnetic spectrum - typically 190 to 900 nm
What are the approximate wavelengths of the UV range?
100 to 400 nm
What are the approximate wavelengths of the visible range?
400 to 800 nm
Some UV-Vis spectrophotometers have an extended wavelength range, what part of the electromagnetic spectrum is this?
Near-infrared (800 to 3200 nm)
What is incident light?
Light that comes from a source and hits the subject
What is transmitted light?
The light after it has passed through the subject
From matter, the transmitted light can be…
Reflected, scattered, transmitted, or absorbed
What are the 3 energies an atom has?
Electronic, vibrational, and rotational
What is the total potential energy of an atom?
The sum of its electronic, vibrational, and rotational energies
What does the energy from the incident light do to an atom?
It causes the electrons to transition to different energy levels
What is the ‘ground state’ of an atom?
The normal, stable state of the atom; where the electrons are at their lowest possible energy levels
What is the ‘excited state’ of an atom?
The electrons temporarily move to higher energy levels
How does UV-Vis work to identify the matter? (in terms of the atom)
- The incident light excites the matter, making it less stable.
- Then it is able to absorb specific levels of light.
- Then you can compare your spectrum to known spectra
The amount of incident light a molecule can absorb is specific to…
The molecule’s structure and the electronic transitions it can undergo
