Absorbance synchronisation

The drive of the dispersing device is synchronised with the x-axis of the recorder or fed directly to a computer, so that this indicates the wavelength of radiation reaching the detector. The signal from the detector is transmitted to the y-axis of the recorder or to a computer and this indicates how much radiation is absorbed by the sample at any particular wavelength. 

Fig. 4.6. Schematic representation of absorbance/transmittance versus time curves. The symbols give the data points for three wavelengths, measured r tively one after another. Synchronisation is obtained by taking int polated values at equal times (perpendicular lines).

Both the monochromators are adjusted to the same wavelength, the reference is taken, and the absorbance of the sample is measured. Afterwards the next wavelength is selected. In this type of measurement the irradiation times differ for the various wavelengths. Therefore the data points have to be synchronised as explained in Fig. 4.6. 

In Fig. 4.31 an example is given controlling a dye laser by one microprocessor and a UVA is-spectrometer by another. These two microprocessors are interconnected via data and control lines. Their programs are synchronised. The first microprocessor controls the spectrometer, the second an optical multichannel analyser, which rapidly takes emission spectra during the time the laser pumps the dye solution. Both have to be synchronised with the spectrometer which takes the absorbance spectra. The laser has to be triggered by the optical multichannel analyser. 

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