INFICON RQCM - Quartz Crystal Microbalance Research System - Manual (Page 95)

RQCM – RESEARCH QUARTZ CRYSTAL MICROBALANCE
GLOSSARY 11-1
11 GLOSSARY
Conductance The ability to conduct. Conductance is the inverse of resistance.
Conductance = 1/Resistance, or Resistance = 1/Conductance.
The units of resistance are Ohms [Ω = V/A] and the units of conductance are Siemens
(S = A/V].
CPVC Abbreviation for chlorinated polyvinyl chloride, a resin patented by Goodrich, it has
excellent mechanical strength and stability over temperature, and offers good
resistance over a selective range of chemicals.
Crystal Bandwidth Refers to the crystal’s frequency response range, bounced by the frequency values
cross at half the resonance frequency’s magnitude. It is defined as f
o
/Q (resonance
frequency/crystal Q).
Crystal Holder A device that houses the crystal and provides connections to the crystal’s electrodes
via a coaxial connector.
Crystal Q A figure of merit used in describing the "sharpness" of the crystal response. (It is also
called crystal quality factor.)
Kynar® Pennwalt’s registered trademark of Polyvinilidene Fluoride (PVDF), a homopolymer
of 1,1-di-fluoro-ethene, is a tough thermoplastic that offers unique properties
including: high chemical inertness, low permeability to gases and liquids, resistance to
radiation and excellent mechanical strength and toughness. Visit
www.atofinachemicals.com for more detailed information.
Picofarad 10 -12 farads. A common unit of capacitance (abbreviated as pfd). By definition, 1
farad will store a 1 Coulomb charge when connected across a 1 volt potential.
PLO Phase Lock Oscillator. A type of electronic circuit in which the frequency and the
phase of the Voltage Controlled Oscillator (VCO) is locked to the frequency and the
phase of a reference signal (in our case the signal from the sensing crystal).
Quadrature (current) Refers to the imaginary component of the current through the shunt capacitance, C
S
.
RQCM INFICON QCM instrument’s model name, which stands for Research Quartz Crystal
Microbalance.
RTD Resistance Temperature Detector. A device that changes its resistance as a function of
temperature.
Shunt Capacitance Effective capacitance due to the electrodes on the crystal. This is the "unwanted"
capacitance we try to cancel out (along with the capacitance in the cable and the holder
of course) while adjusting the Fine & Coarse capacitance cancellation on the Crystal
Measurement Channel(s) on the RQCM.
Teflon® DuPont Company’s registered trademark of Perfluoroalkoxy Fluorocarbon Resin, a
class of Teflon that offers excellent inertness to aqueous acid and aqueous alkaline,
superior resistance over a wide range of pH. Visit www.dupont-dow.com for more
information.
VCO Voltage Controlled Oscillator. An oscillator circuit designed so that the output
frequency can be controlled by applying a voltage to its control or tuning port.