Summary: SLS Manual
1. Prepare 1 mL of the solution: ~40 mg/mL (must be purified same way as for
DLS- see DLS manual).
2. Prepare 2 cells- with your solvent and with benzene.
3. Before measurement turn ON laser for 10 min. Open SLS program on the
4. `A' Dark Count Rate: - Experimental Parameters command button in the
lower part of the screen. Block the light to the PMT. Enter 10 seconds in the
Duration/Repeat field. Click on the Dark Count Rate command button. The
dark count rate is the total photons counted divided by the duration in seconds.
The units are counts/second, abbreviated cps. Click OK command button and
notice that the measured dark count rate is automatically transferred to the
appropriate field. Since the dark count rates are normally small, the fluctuations
are large. Therefore, counting for ten seconds yields smaller fluctuations, and is
easier to estimate the true dark count rate (359 cps is ok). If it is too high - turn off
5. CORRECT PINHOLE: Click on the Set Detector Angle. Turn arm to 90
degree. Try pinhole 1, 2 and 3 with duration = 0.1 s for your concentration. Click
on the Dark Count Rate should be ~ 100 000. No more than 500 kps.
6. Open Experimental Parameters- system has inserted `A' Dark Count Rate