10-62
Another potential source for error in the charge measurement is the use of automatic
Sensitivity
control, since about 3 msec is required for this measurement, during
which time no measurement can be taken. This error is only significant if the time
constant of the cell is short. In these cases, it is better to use manual
Sensitivity
.
However, for most BE experiments, the automatic Sensitivity control gives the most
accurate results. If the manual
Sensitivity
selection is too low, then accuracy is lost,
but if it is too high, overload will occur and the experiment has to be repeated.
Using a working electrode with a large surface area can lead to oscillation in the
electronic circuits. To stabilize the system, a 0.1
µ
F capacitor is automatically
connected between the reference and auxiliary electrodes. The stabilizing
capacitance can be increased or removed using the
Manual
option for
Stabilizing
Capacitor
in the
Method Menu
. However, there is generally no need to use the
Manual
option.
Mode = BE
General Parameters
Initial E (mV) = 0 -3276 to 3276
Sample Interval (msec) = 1000 100 to 65535
End Current Ratio (per thousand) = 10 1 to 1000
Sensitivity = Auto Auto, 100 mA/V to 100 nA/V
There are no
Specific Parameters
.
NOTE: Once the End Current Ratio has been reached, the experiment
should be ended by clicking Stop in the Control Menu (or F5).
Comment:
The maximum file length is 4096 data points.
Graphics Menu
Single Graph
displays the
Charge vs. Time
plot. The
Current vs. Time
plot
can be displayed using
Data Type
in
Graphics
or
Results Options
. The
shape of these plots can indicate chemical reactivity of the electrolyzed
species.
Analysis Menu
The
Auto
option for
Results Graph
displays the same plot as
Single Graph
,
and Init i, End i, i ratio, Time, Total Q and Net Q are listed in the
Main
window (Net Q is the Total Q minus the background Q, where the background
i is assumed to be End i).
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