Cornelius DPC 230 Especificaciones descargar pdf (Pagina 32)

26 Typical Applications

stopped after a defined acquisition time. Activate the ‘Stop T’ button if you want to stop after

a specified time.

‘Max Buffer Size’ defines a buffer in the RAM of the computer. If enough RAM is available

the buffer size should be as large as or larger than the specified file size. The SPCM software

then stores the time-tag data into the RAM before it writes them to the hard disc. The data

readout is then not slowed down by hard disc operations.

The experiment trigger is not used; the setting is ‘none’. You may use the experiment trigger

if you want to start the recording synchronously with an external event.

‘Collection time defines the acquisition time for the ‘Stop T

option. ‘Display Time’ is the up-

date interval for the online display.

Fig. 36: FCS: Measurement control part of the ‘System Parameters’ panel. Left without, right with saving of the

time-tag data.

The online display is configured via the configure panel shown in Fig. 37. With the settings

shown decay curves, FCS curves, and MCS (intensity) traces are calculated. FCS curves are

calculated by a multi-tau algorithm, and within a correlation time window of 1 ms. The MCS

traces are displayed at a resolution of 1 ms per point.

The SPCM software is able to run a fit on the calculated FCS data. The setting shown left are

without, the settings shown right with an FCS fit. The model contains two diffusion times,

tau 1 and tau 2, and a triplet time, Tau trip. F is the relative triplet population, N the number of

molecules in the detection volume, and Y the relative amplitude of the fast diffusion compo-

nent. For the online fit we recommend to use a simple model, preferably one diffusion time

and a triplet time. The start values of the fit procedure are defined on the right of the ‘Config-

ure’ panel.

Fig. 37: Configuration of the online display. Decay curves, FCS curves, and an MCS trace are displayed. The left

setup is without, the right setup with an FCS fit.

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Cornelius DPC 230 Especificaciones Pagina 32