Metrohm 746 VA Trace Analyzer - Manual (Page 338)

5.7.3 Alphabetical instruction list
746 VA Trace Analyzer / 747 VA Stand
5-187
AC2MODE Page: O, S Stand: M, A Abbreviation: AC2
Instructions t/s Main parameters Auxiliary parameters
––––––––––––– ––––– ––––––––––––––––––––––––– –––––––––––––––––––––––––
## .. AC2MODE ..... U.ampl ........mV Modul.freq. ........Hz
t.step ........s Prep.cycles ........
Ph.angle ........° Meas.cycles ........
Function AC2 measurement mode for alternating current voltammetry of the 2
nd
harmonic.
Application Alternating current voltammetry with the AC2MODE measurement mode is
primarily suitable for determinations based on reversible redox reactions
(e.g. Zn in HCl). Compared with the
AC1MODE measurement mode, an in-
crease in sensitivity, resolution and separation efficiency is often
obtained.
Parameter Range; Default value / Meaning
U.ampl 1...35 mV; 20 mV
Effective voltage amplitude
Effective voltage amplitude (RMS voltage amplitude = maximum
voltage amplitude
// û2) of the superimposed alternating voltage.
t.step 0.05...9.9 s; 0.3 s
Time interval for voltage step
Time interval after which the voltage in the sweep is increased or
decreased by the amount
U.step .
The following condition applies to the definition of t.step :
Meas.cyc. + Prep.cyc.
t.step > ––––––––––––––––––––– + t.drop + 30 ms
Modul.freq.
Ph.angle -90...90°; 45°
Phase angle
Phase shift of the alternating voltage in regard to the measurement
interval for current addition or subtraction.
Modul.freq. 10...250 Hz; 25/30 Hz for 50/60 Hz
Modulation frequency
Modulation frequency of the superimposed alternating voltage.
Prep.cycles 0...255; 0
Number of preparation cycles
Number of alternating voltage cycles without current measurement
which are performed for every voltage step before the measurement
cycles.
Meas.cycles 1...24; 2
Number of measurement cycles
Number of alternating voltage cycles with current measurement which
are performed for every voltage step.
The following condition holds for the definition of
Meas.cycles :
Meas.cycles < Modul.freq. * 0.1 s