The structure of the uv vis spectrophotometer is mainly composed of a power source, a light source, a monochromator, a sample chamber, a photoelectric converter, a preamplifier, a data processing, and a peripheral device.
Light source: Refers to a glowing object. The ideal source should provide continuous radiation, the intensity of the light must be large enough, and its intensity should not vary significantly with wavelength throughout the spectral region. Of course, the ideal source is non-existent, and no such source provides sufficient and stable optical radiation at all wavelength points. Therefore, different light sources are used depending on the wavelength.
Tungsten lamp: 320-1100nm (visible area) Xenon lamp: 190-400nm (ultraviolet area) Monochromator: A device used to decompose mixed light from a light source into monochromatic light and to change the wavelength at will. It mainly consists of an entrance slit, an exit slit, a dispersive element and a collimating mirror. In which the dispersive element is the most important, because its quality determines the quality of the monochromator.
Sample chamber: A cassette device used to hold test samples. Photoelectric converter: converts a weak optical signal into a weak electrical signal. The light intensity passing through the test solution and the reference solution can be detected and displayed as an electrical signal for reflecting the light intensity ratio of the test solution to the reference solution. Generally, the detectors used in the uv vis spectrophotometer
include silicon photo cells, phototube, and photomultiplier tubes. Today, due to the rapid development of semiconductor technology, the performance of photovoltaic cells is getting better and better, and the price of photomultiplier tubes is getting lower and lower, so the phototube was gradually eliminated.
Preamplifier: Generally consists of a high-impedance integrated operational amplifier that performs micro-current (voltage) amplification. DC regulated power supply: DC working power that constitutes different voltages (currents) to meet the various load requirements of the instrument. Display: LED, LCD voltmeter.