Figure 9 absorbance by the rules of the Lambert (Lambert's Law)
Rule 5.2.2 of beer (Beer's law) Beer's Law (1852) said. Light absorbed is proportional to the concentration of the liquid which, when calculated, as well as the rule of Lambert will have equation
It = I0 x 10-kc -----------. ------------ (2)
when the two rules together. (Beer-Lambert's law) by adding the equations (1) and Equation (2) will be the new equation is as follows:
It = I0 x 10-εct ---------------. -------- (3)
The light shines through. (Transmittance, T) is equal to It / I0 and light absorption (absorbance, A, or optical density, OD) is equal to log (I0 / It) Therefore
A = εct ----------. ------------- (4)
or A = -log T ----------------------- (5)
epsilon =. molar absorptivity substance is ε constant at each wavelength
is measured Mole-1cm-1
C = Concentration in Mole / L
T = thickness of solution cm
5.3 Components spectroscopy Four. instrumental (Spectrophotometer components)
The main components of UV - Visible million. Spectrophotometry meter has five sections
as follows: 1. Light Source (Light Source)
2. The selected wavelength (wavelength Selector)
3. Containers substance (cell or cuvette)
4. Sensor (detector).
5. The recording and signal processing (recorder and processor)
has arranged all the components as shown in Figure 10 and Figure UV - Visible million. Spectrophotometry meter Simple 5.3.1. Light sources (light source) light source in spectroscopy photometer must provide radiation in wavelengths that require continuous and constant over time. The light intensity is sufficient for the wavelength ultraviolet lamps deuterium (deuterium lamp) as a light source. The light in the 185-375 nm range is the deuterium atoms in the ground state energy stimulus out of tungsten (tungsten filament lamp) to cover the wavelength range from visible light is 320-2500. nm principle is similar to a conventional tungsten bulbs. An electric current through the tungsten wire, hot and emitting radiation is released typically turn left before for about 30 minutes to make sure the tube deuterium or tungsten light intensity consistent Figure 11. deuterium lamp (left) and tungsten (right) 5.3.2 The selected wavelength (wavelength selector) is used to separate out the wavelengths of the light source. The light that has multiple wavelengths (polychromatic wavelength) as the light in a narrow range or a single wavelength. (Monochromatic wavelength) tools before use or prism. Filters for wavelength separation But switching to mono chromate router. (Monochromater) a grating (grating) reflect light, which has a small groove. Many parallel Light from the light source is incident on the surface of the groove. Then reflected at various angles. We select only specific wavelengths of light to pass through the exit (exit slit) to the sample.
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