Spectrophotometer Flashcards
is defined as the measurement of the intensity of light selected wavelengths.
Spectroscopy
measures the intensity of light entering the sample and light exiting a sample and compares the two intensities.
Spectrophotometer
Spectroscopy operates on the principle of?
Beer’s – Lambert Law
states that the concentration of a substance is directly proportional to the amount of light absorbed or inversely proportional to the logarithm of the transmitted light.
Beer’s Law
provide a sufficient source of light which is suitable for making a measurement. The light source typically yields a high output of polychromatic light over a wide range of the spectrum.
Light Source
Types of Light Source:
- Incandescent Lamps
- Laser
accepts polychromatic input light from a lamp and puts out monochromatic lights.
Monochromator
Monochromatic consists of these parts:
- Entrance Slit
- Collimating Lens or mirror
- Dispersion Element
- Focusing lenses or mirror
- Exit slit
a special plate with hundreds of parallel grooved lines.
Dispersion Devices
These lines act to separate the white light into the visible light spectrum. More lines the smaller the wavelength resolution.
Grooved lines
Combination of lenses, slits, and mirrors. Relay and focus light through the instrument.
Focusing Devices
designed to hold samples for spectroscopic experiments, made plastics, glass or silica should be as clear as possible, without impurities that might affects as spectroscopic reading.
Cuvettes or Curvet
convert radiant energy (Photons) into an electrical signal.
Detectors
Simplest photodetectors that produce current proportional to the intensity of the light striking them.
- Photocell
- Phototubes
the data from a detector are displayed by a readout device, sushasan analog meter, a light beam reflected on a scale, or a digital or LCD. The output can also be transmitted to a computer or printer.
Display Devices
