UV-Vis Spectrophotometry Flashcards
- powerful analytical technique used in various scientific fields to measure light absorbance across the electromagnetic spectrum’s ultraviolet (UV) and visible (Vis) ranges
- provides valuable information about the properties of materials and their interactions with light
UV-Vis spectrophotometry
Basic Principles of UV-Vis spectrophotometry
- the electromagnetic spectrum
- wavelength and frequency
- origin of UV-Visible spectra
- transmittance and absorbance
comprise only a small part of the electromagnetic spectrum, which includes such other forms of radiation as radio, infrared (IR), cosmic, and X rays
Ultraviolet (UV) and visible radiation
electromagnetic radiation can be cosidered a combination of alternating electric ang magnetic fields that travel through space in wave motion
wavelength and frequency
- we want only absorbance to occur
- because light is a form of energy, absorption of light by matter causes the energy content of the molecules (or atoms) to increase
origin of UV-visible spectra
when light passes through or is reflected from a sample, the amount of light abosrbed is the difference between the incident radiation (Io) and the transmitted radiation (I)
transmittance and absorbance
amount of light absorbed
absorbance
light that passes throught a sample
transmittance
General Components of UV-Vis spectrophotometry
- light source
- monochromator
- cuvette (sample holder)
- detector
many spectrophotometers alternate between a halogen lamp for visible range and a deuterium lamp for ultraviolet region
light source
visible range
halogen lamp
ultraviolet region
deuterium lamp
device that disperses monochromatic from polychromatic light
monochromator
process of breaking down light into its constituent wavelengths in a manner similar to a rainbow
dispersion
tool utilized to separate spectral lines
diffraction grating
