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How to take Spectrum in Shimadzu UV-1800 in UV Probe Software?

  • Ultraviolet-visible (UV-vis) spectroscopy is used to obtain the absorbance spectra of a compound in solution or as a solid. What is actually being observed spectroscopically is the absorbance of light energy or electromagnetic radiation, which excites electrons from the ground state to the first singlet excited state of the compound or material. 
  • The UV-vis region of energy for the electromagnetic spectrum covers 1.5 - 6.2 eV which relates to a wavelength range of 800 - 200 nm. The Beer-Lambert Law, Equation-1, is the principle behind absorbance spectroscopy.  
  • For a single wavelength, A is absorbance, ε is the molar absorptivity of the compound or molecule in solution, b is the path length of the cuvette or sample holder (usually 1 cm), and c is the concentration of the solution.
A = εbc

  • All of these instruments have a light source (usually a deuterium or tungsten lamp), a sample holder and a detector, but some have a filter for selecting one wavelength at a time. The single beam instrument (Figure-1) has a filter or a monochromator between the source and the sample to analyze one wavelength at a time. 
  • The double beam instrument (Figure-2) has a single source and a monochromator and then there is a splitter and a series of mirrors to get the beam to a reference sample and the sample to be analyzed, this allows for more accurate readings.  
  • In contrast, the simultaneous instrument (Figure-3) does not have a monochromator between the sample and the source; instead, it has a diode array detector that allows the instrument to simultaneously detect the absorbance at all wavelengths. The simultaneous instrument is usually much faster and more efficient, but all of these types of spectrometers work well.


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