ASTM E902-94(1999)
(Practice)Standard Practice for Checking the Operating Characteristics of X-Ray Photoelectron Spectrometers
Standard Practice for Checking the Operating Characteristics of X-Ray Photoelectron Spectrometers
SCOPE
1.1 This practice covers a procedure for checking some of the operating characteristics of an X-ray photoelectron spectrometer. Tests herein provide checks of the following instrument characteristics: X-ray photoelectron spectroscopy (XPS) signal intensity, background, energy resolution, short-term voltage stability, transmission, and energy scale linearity. It is meant for spectrometers with digital storage of counts in energy channels.
1.2 Limitations -This practice is meant to augment, and not to replace, the calibration procedures recommended by the manufacturer of the spectrometer. This practice is also not meant to be used as a means of comparison between X-ray photoelectron spectrometers, but only as a self-consistent check of the operating characteristics of an individual spectrometer.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation:E902–94 (Reapproved 1999)
Standard Practice for
Checking the Operating Characteristics of X-Ray
Photoelectron Spectrometers
This standard is issued under the fixed designation E902; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 3.2 Additionally, the following terms and abbreviations are
used throughout this practice:
1.1 This practice covers a procedure for checking some of
the operating characteristics of an X-ray photoelectron spec-
trometer. Tests herein provide checks of the following instru-
c = counts
ment characteristics: X-ray photoelectron spectroscopy (XPS)
ch = channel
signal intensity, background, energy resolution, short-term
cps = counts per second
voltage stability, transmission, and energy scale linearity. It is
eV = electron volts
meant for spectrometers with digital storage of counts in
i = numberofdatachannelsacquiredforthepeakof
energy channels.
interest
1.2 Limitations—Thispracticeismeanttoaugment,andnot
n = number of channels
no. = number of
to replace, the calibration procedures recommended by the
S/B = signal-to-background ratio
manufacturer of the spectrometer. This practice is also not
sc = span
meant to be used as a means of comparison between X-ray
Dx = step size, eV, between successive data channels
photoelectron spectrometers, but only as a self-consistent
A = peak area above background, mm
check of the operating characteristics of an individual spec-
B = background height, mm
trometer.
H = maximum peak height above background, mm
1.3 This standard does not purport to address all of the
I = peak area intensity above background, c-eV/s
A
safety concerns, if any, associated with its use. It is the
I = maximum signal intensity above background,
H
responsibility of the user of this standard to establish appro-
cps
priate safety and health practices and determine the applica-
P = peak position on the binding energy scale, eV
bility of regulatory limitations prior to use.
FWHM = full width at half maximum
2. Referenced Documents
4. Significance and Use
2.1 ASTM Standards:
4.1 This practice should first be used to establish the
E673 Terminology Relating to Surface Analysis
operating characteristics of a particular X-ray photoelectron
E1015 Practice for Reporting Spectra in X-ray Photoelec-
spectrometer at a time when the spectrometer performance is
tron Spectroscopy
known to be optimum. Hence, the spectrometer settings in
E1078 Guide for Specimen Handling in Auger Electron
Section 5 and the expected performance figures given in
Spectroscopy, X-ray Photoelectron Spectroscopy, and Sec-
Section 7 are to be taken only as guides, to be supplanted by
ondary Ion Mass Spectrometry
the behavior of the user’s actual spectrometer.
4.2 Subsequently, this practice should be used as a routine
3. Terminology
check, performed at frequent intervals with the same instru-
3.1 Definitions—Terms used in X-ray photoelectron spec-
ment settings, and the results compared with those obtained in
troscopy are defined in Terminology E673.
4.1. Significant deviation from optimum performance may
indicate that the spectrometer requires recalibration or other
maintenance.
This practice is under the jurisdiction of ASTM Committee E-42 on Surface
4.3 Typical analysis settings should be used with this
AnalysisandisthedirectresponsibilityofSubcommitteeE42.03onAugerElectron
Spectroscopy and XPS.
practice.Theuseofsettingsnotspecifiedbythispracticeisleft
Current edition approved Sept. 15, 1994. Published November 1994. Originally
to the discretion of the user, however, the settings should be
published as E902–82. Last previous edition E902–93.
recorded in accordance with Practice E1015 and the same
Annual Book of ASTM Standards, Vol 03.06.
Discontinued. See 1994 Annual Book of ASTM Standards, Vol 03.06. settings should be used consistently whenever this practice is
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E902–94 (1999)
repeated, so that the results obtained will be directly compa- 6. Treatment of Data
rable to previous results.
6.1 Print or plot the spectra as obtained in 5.5-5.7. In
addition:
5. Procedure
6.1.1 Print or plot the Cu 2p line between 938 and 928-
3/2
eV binding energy.
5.1 Obtainaclearcopperspecimen(;99.9%purity)witha
6.1.2 Print or plot the Cu 3p line between 78.5 and
smooth, flat surface; a foil is preferred. This specimen should
3/2
73.5-eV binding energy.
be larger than the analysis area of the spectrometer (the
6.2 For Spectra5.6 and6.1.1—Ifacomputercanbeusedto
analysis area being defined as either the area viewed by the
measure the peak and background, fit the background with a
analyzer or the area of illumination of the X-ray beam,
linear baseline, as shown in Fig. 1, and record I and the
whichever is smaller).The three recommended cleaning meth-
H
endpoints. If a linear background fit is not available, an
odsareasfollows:(1)Etchthespecimenina1-MHClsolution
alternate background shape (for example, an integral back-
for 5 min with constant stirring or ultrasonic agitation, fol-
ground) may be used, however, this background may change
lowedbyarinseindistilledwater;(2)cleanthespecimenwith
metal polish, or (3) abrade the specimen with No. 600 silicon the signal intensity. Whichever background shape is chosen,
the same background shape and endpoints should be used
carbideinanitrogenatmosphere,takingcarethatthetechnique
wheneverthispracticeisrepeated.AlsomeasureB(Note2)for
is carefully reproduced each time.
each spectrum, as shown in Fig. 1.
5.1.1 The choice of cleaning method will depend on the
specimen dimensions, ease of handling, and availability of the
NOTE 2—Some data-processing software packages automatically sup-
necessary cleaning supplies.
press the background, either when the data is collected or when it is
5.1.2 After cleaning the specimen by one of these three
methods, rinse the specimen in ethanol or a similar solvent.
5.1.3 Guide E1078 recommends additional specimen han-
dling precautions that may be required.
5.2 Mount the copper specimen at the usual specimen
position in the spectrometer, and in electrical contact with the
specimen holder.
5.3 Use an ion sputter gun to clean the specimen until the
C1sandO1speakheightsabovebackgroundareeachlessthan
or equal to 10% of the Cu 3p peak height above background.
Ifsputteringisnotavailable,theintensitiesoftheC1sandO1s
peaks may exceed 10% of the Cu 3p peak; in this case, record
the C1s and O1s peak heights above background.
5.4 Set and record the anode material, excitation potential,
emission current, any leakage current, anode height (if adjust-
able), specimen tilt, and the pass energy or slit widths. Use
typicalanalysissettings.Forallspectra,chooseatleasttendata
channels per electron volt and adjust the time per point and
number of sweeps to meet the counting criteria noted in
5.5-5.7. Record these settings in a manner consistent with
Practice E1015 and use them exactly the same way each time
the spectrometer is checked.
5.5 Acquire and store the photoelectron spectrum of the Cu
2p doublet between 963 and 923 eV, with enough scans to
collect at least 10000 counts at the peak maximum.
5.6 Acquire and store the photoelectron spectrum of the Cu
3pdoubletbetween86and66-eVbindingenergy,withenough
scans to collect at least 5000 counts at the peak maximum.
5.7 If using Mg X-rays, acquire and store the spectrum of
the Cu L M M Auger line between 340 and 330 eV (Note
3 4,5 4,5
1) on the binding energy scale. If usingAl X-rays, acquire and
store the spectrum of theAuger line between 573 and 563 eV
on the binding energy scale (Note 1). In either case, acquire
enough scans to collect at least 10000 counts at the peak
maximum.
NOTE 1—Forinstrumentswheretheminimumscanwidthislargerthan NOTE 1—Spectral lines obtained in accordance with procedures in 5.6
recommended, use the minimum allowable scan width. For instruments (bottom) and 6.1.1 (top) illustrating the data treatments described in
where the energy interval cannot be set up in integer steps, use the closest 7.1-7.3.
allowed energy. FIG. 1 Spectral Lines
E902–94 (1999)
displayed.Theusershouldensurethatthebackgroundhasnotbeenaltered
or
before making the background measurement. Information about the
A~j!@c/mm~j!# @eV/mm~j!#
treatmentofbackgroundsforaparticularinstrumentcanoftenbeobtained
I 5 (5)
A~j!
@s/sc~j!# @no.sc~j!# @no.ch/sc~j!#
by contacting the manufacturer of the software package or indirectly by
comparison of computer-acquired data with analog data acquired with the
Record the ratio I /I .
A(3p) A(2p3/2)
same instrument settings over the same energy range.
7.4.1 If a computer cannot be used to measu
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