Principle and structure of fluorescence spectrophotometer

Basic Principle A type of optical instrument belonging to a fluorescence spectrophotometer. It is irradiated with ultraviolet light and blue-violet light emitted by a high-pressure mercury lamp or xenon lamp through a filter into the sample cell to excite the fluorescent substance in the sample to emit fluorescence, and the fluorescence is filtered After and reflection, it is received by the photomultiplier tube, and then displayed in the form of graphs or numbers. Substance fluorescence is produced by the basic principle of fluorescence spectrophotometer under normal conditions. It is a kind of optical instrument belonging to the fluorescence spectrophotometer. It is irradiated into the sample cell by the ultraviolet light and blue-violet light emitted by the high-pressure mercury lamp or xenon lamp through the filter to excite the sample. The fluorescent substance in the fluorescein emits fluorescence. After the fluorescence is filtered and reflected, it is received by the photomultiplier tube, and then displayed in the form of graphs or numbers. The generation of material fluorescence is that the material molecules in the ground state under normal conditions absorb the excitation light and then become the excited state.These molecules in the excited state are unstable, and part of the energy is returned to the ground state in the form of light. It emits to produce fluorescence. 　　Due to the different molecular structure of different substances, the distribution of excited state energy levels has their own different characteristics. This characteristic is reflected in fluorescence as various substances have their own fluorescence excitation and emission spectra;, Therefore, the difference in fluorescence excitation and emission spectra can be used to qualitatively identify substances. In the solution, when the concentration of the fluorescent substance is low, its fluorescence intensity and the concentration of the substance usually have a good proportional relationship, that is, IFu003dKC. This relationship can be used for quantitative analysis of fluorescent substances, and ultraviolet-visible spectroscopy The photometric method is similar, and the fluorescence analysis is usually carried out by the standard curve method.　　Basic structure 　　1. Light source: 　　 is a high-pressure mercury vapor lamp or a xenon arc lamp, the latter can emit a continuous spectrum of greater intensity, and the intensity is almost equal in the range of 300nm to 400nm, so it is more commonly used.　　2. Excitation monochromator: 　　 Placed between the light source and the sample chamber is the excitation monochromator or the first monochromator to filter out a specific excitation spectrum.　　3. Emission monochromator: 　　 is placed between the sample chamber and the detector is the emission monochromator or the second monochromator, and the grating is often used as the monochromator. Filter out specific emission spectra.　　4. Sample chamber: 　　 usually consists of a quartz cell (for liquid samples) or a solid sample holder (powder or sheet samples). When measuring liquids, the light source and the detector are arranged at a right angle; when measuring solids, the light source and the detector are arranged at an acute angle.　　 5. Detector: 　 generally use photoelectric tube or photomultiplier tube as detector. The optical signal can be amplified and converted into an electrical signal. Welcome to visit the official website: www.ehuahai.com To buy instruments, please go to www.51gk.com