The spectral range of the Micro Spectrophotometer
The visible light region with a wavelength range of 380~780 nm and the ultraviolet light region with a wavelength range of 200 ~ 380 nm are included. Different light sources have their own unique emission spectra, so different light sources can be used as the light source of the instrument.
Tungsten lamp emission spectrum: tungsten light source emitted by the wavelength of 380 ~ 820nm spectrum, light through the prism refraction, can be obtained by the red, orange, yellow, green, blue, indigo, violet composition of the continuous chromatography; The chromatograph can be used as a light source for visible light spectrophotometer.
The emission spectrum of the deuterium lamp: the deuterium lamp can emit the spectrum of 190 ~ 400 nm wavelength, which can be used as the light source of the ultraviolet photometer.
Xenon flash emission spectrum: Xenon lamp can emit the spectrum of 200 ~ 850 nm wavelength, can be used as the source of UV-visible photometer. The size of power supply is small, using pulse flash mode work, flash times up to 109 times, the life is longer than deuterium lamp and tungsten lamp.
The absorption spectrum of a substance
If a solution of some substance is placed between the light source and the prism, the spectrum displayed on the screen is no longer the spectrum of the light source, it appears several dark lines, that is, some wavelengths of light in the emission spectrum of the light source disappear due to the absorption of the solution, the spectrum absorbed by the solution is called the absorption spectrum of the solution.
Different substances have different absorption spectra. Therefore, according to the absorption spectrum, the substance contained in the solution can be identified.
The principle of
When light passes through a solution of a substance, the intensity of the light passing through decreases. Because some of the light is reflected or dispersed on the surface of the solution, some of it is absorbed by the substances that make up the solution, and only some of it passes through the solution.
Incident light = reflected light + dispersed light + absorbed light + transmitted light
If we use distilled water (or the solvent that makes up the solution) as a "blank" to correct for the loss of incident light due to factors such as reflection, dispersion, etc., then:
Incident light = absorbed light ten transmitted light
The principle of spectrophotometer for sample concentration determination is based on the Lambert-Beer law,A = ε B, C
Where, A -- is the absorbance of A substance;
ε -- is the light absorption coefficient of a substance;
B -- is the length of optical path (optical path);
C -- is the concentration of the substance.