INFICON RQCM - Quartz Crystal Microbalance Research System - Manual (Page 64)

RQCM – RESEARCH QUARTZ CRYSTAL MICROBALANCE
THEORY OF OPERATION 5-12
When the above complex conductance is plotted in polar coordinates, one obtains a circle as
shown in Figure 20. The vector V indicates the magnitude and phase of the crystal current
divided by the applied voltage. The real part of the conductance is indicated by the vector R and
the imaginary part is indicated by the vector I.
Figure 20 Polar Admittance Plot of High Q Crystal
no
FREQUENCY = 4.987966 MHz
RESISTANCE = 8.6Ω
BANDWIDTH ≈ 38Hz
Q ≈130,000
OSCILLATOR
PHASE ERROR
OF 15 DEGREES
OSCILLATOR
LOCK POINT
ZERO PHASE
ERROR LOCK POINT
TRUE SERIES RESONANCE