Metrohm 746 VA Trace Analyzer - Manual (Page 445)

5.7 Program instructions
746 VA Trace Analyzer / 747 VA Stand
5-294
The phase dependent differences in the current measurements give
peak-shaped curves which can be evaluated using the baselines of type
linear , polynom or expon. (see section 5.6.3).
I
U U.peak
I.peak
Comments • The SQWMODE measurement mode can be used with all types of
electrodes together with the instructions MEAS , SWEEP , DSWEEP ,
FSWEEP or TSWEEP .
• The electrode type DME , SMDE , HMDE or RDE must be entered before
the SQWMODE measurement mode.
• If the SQWMODE measurement mode is used with the voltage sweep
SWEEP and the electrode type HMDE , the potentiostat normally oper-
ates in the operating mode "slow". A switch is made to the operating
mode "fast" when the modulation frequency
Modul.freq. >120 Hz.
• If the SQWMODE measurement mode is used with the voltage sweep
SWEEP and the electrode type SMDE or DME , the setting of the poten-
tiostat depends on the measurement profile. Normally, a switch is
also made from "slow" to "fast" when the modulation frequency
Modul.freq. >120 Hz. With very small signals, however, the operat-
ing mode "slow" is used and with very large signals the operating
mode "fast", irrespective of the pulse time.
• If the SQWMODE measurement mode is used with the voltage sweep
SWEEP and the electrode type RDE , the potentiostat always operates in
the operating mode "fast".
• If the SQWMODE measurement mode is used with the voltage sweep
FSWEEP , the potentiostat always operates in the operating mode "fast"
with all electrode types.
• The quantity t.drop important for the definition of t.step depends
on the type of electrode selected:
DME t.drop = 20 ms
HMDE and RDE t.drop = 0 ms
SMDE t.drop = Drop.size ×× 40 ms
see also SWEEP, FSWEEP, DME, SMDE, HMDE, RDE
n = Meas.cycles
Σ (I
n1
– I
n2
)
n
I =