![]() ![]() Origin offers an easy-to-use interface for beginners, combined with the ability to perform advanced customization as you become more familiar with the application. Origin is the data analysis and graphing software of choice for over half a million scientists and engineers in commercial industries, academia, and government laboratories worldwide. Browser Graph for Multichannel Data Exploration.Float Windows outside of Origin Interface.Extended Templates from OriginLab Website.The aperture diameter, A (cm), required at each resolution level can be calculated using the following formula. In the FTIR instrument, if "AUTO" is set for the aperture, then the aperture is automatically set in accordance with the set resolution. Consequently, the aperture diameter should be selected so that the measurement resolution is not affected by the spread of peaks due to the grazing-incidence light. The size of this grazing-incidence component varies according to the size of the radiation source. This grazing-incidence light is handled in the same way as normal incident light, the long-wavelength component is incorporated in the obtained data, as a component with a wavelength longer than actual by an extent proportional to the angle of grazing incidence. The sample is also irradiated with grazing-incidence light, and this is ultimately received at the infrared detector, where it constitutes part of the measured signal. As the source is not a point source, the light entering the interferometer does not consist solely of parallel light. However, not only does such a source not exist in reality, a source of a certain size is used in order to ensure a sufficient level of light intensity at the surface of the infrared detector. ![]() The ideal form of radiation source is a point source. It is not easy to change the actual size of the radiation source, so it is changed artificially by focusing an image of the radiation source at the aperture position and then changing the size of the aperture. With FTIR, an infrared radiation source is incorporated inside the instrument, the sample is irradiated with infrared radiation, and the changes in light intensity are concentrated by a detector. With a camera, light from the subject is projected onto film. In FTIR, the clarity of the spectra (i.e., the sharpness of the peaks) obtained can be changed by selecting a different aperture. ![]() In order to increase the brightness, the shutter speed is reduced, so that the cumulative amount of light reaching the film increases. Narrowing the aperture gives a sharper photograph, but because this also reduces the light intensity, the resulting photograph is darker. The aperture of a camera is a mechanism by which the light that is received from the subject is focused at the aperture position, and the quantity of light is adjusted. On some occasions, a low resolution is set for gaseous samples if the purpose is quantification. ![]() Therefore, it is undesirable for the resolution to be increased more than necessary.įor this reason, the resolution is usually set to approximately 4 cm -1 for solid and liquid samples, and to approximately 1 cm -1 or 0.5 cm -1 for gaseous samples. This is because the molecules of the solid or liquid are influenced by other molecules around them, causing the actual peaks to broaden.Īlso, if the resolution is increased, a smaller aperture is selected in the way described later, and the intensity of the light entering the detector is reduced, increasing the relative amount of noise in the spectra. In fact, although this works for gaseous samples, there are cases with solid and liquid samples where the resolution of the data obtained does not improve even if a higher resolution is set. To obtain sharper spectra (i.e., spectra with a higher resolution), a value such as 2 cm -1 or 1 cm -1 is set. For example, if 4 cm -1 is selected, spectra will be obtained at intervals of approximately 2 cm -1. It indicates the degree of fineness of the data obtained by measurement (i.e., the minimum peak interval that can be distinguished). The resolution can be set to values such as 16 cm -1, 8 cm -1, 4 cm -1, or 2 cm -1. Resolution is one of the measurement parameters involved in obtaining spectra with FTIR. ![]()
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