SPECS PHOIBOS Series User Manual

Single and Multichannel Detector (SCD) / (MCD)
Figure 19: Detection Efficiency for Electrons and Ions
The BIAS voltage produced in the HSA3500 determines the conversion energy
E
conv
=− q U
BIAS
 E
pass
(23)
of the charged particles impinging on the CEM. The proper conversion voltage has two
requirements which must be simultaneously fulfilled:
● the particles energy should be suitable for maximum yield of secondary electron
emission at the impact on the CEM wall. For electrons this is roughly in the en-
ergy range between 100 - 800 eV.
● For ions, the yield increases with the kinetic energy roughly up to 10 keV.
Standard settings are:
● for electrons: U
BIAS
= + 90 V.
● for ions: U
BIAS
= - 2000 V.
3.5.5 Spectrometer Voltage U
0
The main retardation voltage of the spectrometer U0 is numerically equal to the differ-
ence between kinetic energy (Ekin) and pass energy (Epass) + Work Function (WF). Be-
cause of the different polarity of the lens and hemisphere voltages in the different ana-
lyzer modes (XPS,AES,UPS or ISS) the value U0 is calculated by
U
groundplate
= E
kin
− E
pass
− WF / q
(24)
The spectrometer voltage is applied on a groundplate and lens element 10 (Figure 5:
Analyzer Main Components and Voltage Principle page 10 and Figure 33: Schematics of
the 12-pin Analyzer Feedthrough page 72 as well as the comments in section , "" on
page .
Example:
WF=4.5 eV, Ekin =1000 eV, Ep= 100V
PHOIBOS 33

SPECS PHOIBOS Series Specifications

General

Brand	SPECS
Model	PHOIBOS Series
Category	Measuring Instruments
Language	English