Analysis: Principles of Instrumentation Flashcards
Beer’s Law
fundamental principles of absorption spectroscopy
Light Source
provides the energy that the sample will modify or attenuate by absorption
- Continuum
2. Line
Types of Light Source
Continuum
emits radiation that changes in intensity very slowly as a function of wavelength
line
emit a limited number of discrete lines or bands of radiation
Monochromator
used to select the appropriate wavelength
i. Filter
ii. Prism
iii. Grating monochromators
iv. Holographic gratings
Types of monochromator
- presample filters
2. postsample filters
types of filters
Presample filters
limit the wavelengths of light that enter the sample
Postsample filters
allow multiwavelength light to pass through the sample and then to break up this light into its component wavelengths
Photodetector
Converts transmitted radiant energy into an equivalent amount of electrical energy
i. Photomultiplier tubes (PMTs)
ii. Photovoltaic
iii. Vacuum Phototubes
iv. Silicon Diode Transducers
v. Multichannel Photon Transducers
Types of photodetectors
i. Photomultiplier tubes (PMTs)
o Most common type
o highly sensitive to UV and visible radiation
ii. Photovoltaic
o used for detecting and measuring radiation in the visible region
iii. Vacuum Phototubes
o has a semicylindrical cathode and a wire anode sealed inside an evacuated transparent envelope
