ISO 13084:2025

Surface chemical analysis - Mass spectrometries - Calibration of the mass scale for a time-of-flight secondary ion mass spectrometer

This document specifies a method to optimize the mass calibration accuracy in time-of-flight secondary ion mass spectrometry (SIMS) instruments used for general analytical purposes. This document is only applicable to time-of-flight instruments but is not restricted to any particular instrument design. This document gives guidance for some of the instrumental parameters that can be optimized using this procedure and the types of generic peaks suitable to calibrate the mass scale for optimum mass accuracy.

Titre manque

General Information

• Status: Published
• Publication Date: 22-Oct-2025
• ICS: 71.040.40 - Chemical analysis
• Technical Committee: ISO/TC 201/SC 6 - Secondary ion mass spectrometry
• Drafting Committee: ISO/TC 201/SC 6/WG 4 - Organic and Nano SIMS
• Current Stage: 6060 - International Standard published
• Start Date: 23-Oct-2025
• Due Date: 16-Mar-2026
• Completion Date: 23-Oct-2025

Relations

• Revises: ISO 13084:2018 - Surface chemical analysis - Secondary ion mass spectrometry - Calibration of the mass scale for a time-of-flight secondary ion mass spectrometer
• Effective Date: 21-Sep-2024

Overview

ISO 13084:2025 - Surface chemical analysis - Mass spectrometries - Calibration of the mass scale for a time‑of‑flight secondary ion mass spectrometer (ToF‑SIMS) - specifies a practical method to optimize mass calibration accuracy for ToF‑SIMS instruments used in general analytical work. The standard is instrument‑design agnostic (applies only to ToF instruments) and provides guidance on sample preparation, spectral data acquisition, peak fitting, iterative optimization of instrumental parameters, and calibration procedures to achieve improved relative mass accuracy (reported in ppm).

Keywords: ISO 13084:2025, ToF‑SIMS calibration, mass accuracy, mass spectrometry calibration, surface chemical analysis.

Key technical topics and requirements

• Scope and approach
  • Focused on improving mass scale calibration and reducing mass errors that arise from kinetic energy distributions, non‑optimized instrument parameters, and extrapolation beyond calibration ranges.
• Reference sample and sample prep
  • Uses a thin polycarbonate (PC) film on a conducting substrate (e.g., silicon) as a readily available reference. Typical film thickness guidance: 10 nm to 100 nm; recommended PC solution preparation and spin‑casting steps are provided.
• Data acquisition
  • Guidance on ToF instrument settings to obtain spectra suitable for calibration, including recommended acquisition time and counts to ensure quality spectra.
• Peak fitting and mass accuracy calculation
  • Uses an asymmetric Gaussian fit to determine peak centers (recommended to fit intensities above 50% of the peak maximum to avoid neighbouring interference).
  • Defines mass accuracy ΔM (difference between measured peak center and true mass) and relative mass accuracy W (expressed in ppm).
• Optimization and calibration procedure
  • Iterative optimization using a set of specific hydrocarbon peaks from PC (19 peaks) to tune instrumental parameters for best mass accuracy, followed by a general calibration procedure for organics and inorganics.
• Uncertainty and annexes
  • Informative Annex A addresses calibration uncertainty; Annex B describes an internal addition method for calibration enhancement.

Practical applications and users

• Target users:
  • Surface analysts, materials scientists, forensic labs, semiconductor/metrology labs, ToF‑SIMS instrument manufacturers, and calibration/quality assurance laboratories.
• Practical benefits:
  • Improves confidence in molecular identification from ToF‑SIMS spectra, enabling discrimination of isobaric species (e.g., CHx vs N or Si), supports routine instrument maintenance, and reduces interlaboratory variability in mass accuracy.

Related standards

• ISO 23830 (referenced for high‑quality SIMS spectral acquisition practices)
• ISO technical committee: ISO/TC 201, Surface chemical analysis (Subcommittee SC 6: Mass spectrometries)

ISO 13084:2025 is a practical, implementable standard to raise ToF‑SIMS mass calibration performance and to provide traceable, uncertainty‑aware mass measurements for surface chemical analysis.

Standards Content (Sample)

International
Standard
ISO 13084
Third edition
Surface chemical analysis — Mass
2025-10
spectrometries — Calibration of
the mass scale for a time-of-flight
secondary ion mass spectrometer
Reference number
© ISO 2025
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
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CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms. 1
4.1 Symbols .1
4.2 Abbreviated terms .2
5 Outline of method . 2
6 Method for improving mass accuracy . 3
6.1 Obtaining the reference sample for optimization .3
6.2 Preparation of polycarbonate sample.3
6.3 Obtaining the SIMS spectral data .4
6.4 Calculating mass accuracy .4
6.5 Optimizing instrumental parameters .7
6.6 Calibration procedure .8
Annex A (informative) Calibration uncertainty . 10
Annex B (informative) Internal addition method .11
Bibliography .13

iii
Foreword
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bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
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The procedures used to develop this document and those intended for its further maintenance are described
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of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
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Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 201, Surface chemical analysis, Subcommittee
SC 6, Mass spectrometries.
This third edition cancels and replaces the second edition (ISO 13084:2018), which has been technically
revised.
The main changes are as follows:
— addition of informative Annex B.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

iv
Introduction
Secondary ion mass spectrometry (SIMS) is a powerful technique for the analysis of organic and molecular
surfaces. Over the last decade, instrumentation has improved significantly so that modern instruments
[2]
now have very high repeatability and constancy . A growing need is for the identification of the chemical
composition of complex molecules from accurate measurements of the mass of the secondary ions. The
relative mass accuracy to do this and to distinguish between molecules that contain different chemical
constituents, but are of the same nominal mass (rounded to the nearest integer mass), is thus an important
parameter. A relative mass accuracy of better than 10 ppm is required to distinguish between C H
2 4
(28,031 30 u) and Si (27,976 92 u) in a parent ion with total mass up to 1 000 u, and between CH (14,015 65 u)
and N (14,003 07 u) in parent ions with total mass up to 300 u. However, in a recent interlaboratory
[3]
study , the average fractional mass accuracy was found to be 150 ppm, which is significantly worse than
[4]
the accuracy needed for unambiguous identification of ions. A detailed study shows that the key factors
degrading the accuracy include the large kinetic energy distribution of secondary ions, non-optimized
instrument parameters and extrapolation of the mass scale calibration.
This document describes a simple method, using locally sourced material, to optimize the instrumental
parameters, as well as a procedure to ensure that accurate calibration of the mass scale is achieved within a
selectable uncertainty.
v
International Standard ISO 13084:2025(en)
Surface chemical analysis — Mass spectrometries —
Calibration of the mass scale for a time-of-flight secondary
ion mass spectrometer
1 Scope
This document specifies a method to optimize the mass calibration accuracy in time-of-flight secondary
ion mass spectrometry (SIMS) instruments used for general analytical purposes. This document is only
applicable to time-of-flight instruments but is not restricted to any particular instrument design. This
document gives guidance for some of the instrumental parameters that can be optimized using this
procedure and the types of generic peaks suitable to calibrate the mass scale for optimum mass accuracy.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 Symbols and abbreviated terms
4.1 Symbols
m mass of interest
m calibration mass 1
m calibration mass 2
M mass (u)
M peak centre (u)
ΔM mass accuracy (u)
M measured peak mass (u)
P
M true mass (u)
T
U(m) mass uncertainty for a mass, m, arising from calibration
U uncertainty in the accurate mass measurement of m
1 1
U uncertainty in the accurate mass measurement of m
2 2
U average uncertainty in an accurate mass measurement
V reflector or acceptance voltage (V)
R
W relative mass accuracy
x number of carbon atoms
y number of hydrogen atoms
G scaling term
α asymmetry term
σ(ΔM) standard deviation of the mass accuracy for a number of peaks
+
σ average of the standard deviations of ΔM for each of the four C H cascades with 4, 6, 7 and 8 car-
M x y
bon atoms
4.2 Abbreviated terms
MEMS micro-electromechanical system
PC polycarbonate
ppm parts per million
r/min revolutions per minute
SIMS secondary ion mass spectrometry
THF tetrahydrofuran
ToF time-of-flight
5 Outline of method
Here, the method is outlined so that the detailed procedure, given in Clause 6, can be understood in
context. First, to optimize a time-of-flight mass spectrometer using this procedure, obtain a thin film of
polycarbonate (PC) on a conducting substrate (silicon). The optimization procedure is achieved by carrying
out the procedures in 6.3 to 6.5 iteratively; it uses 19 specific C H peaks in the PC positive-ion mass
x y
spectrum. In 6.6, a general calibration procedure is given which provides the rules by which calibrations
for inorganics and organics may be incorporated. This leads to a new generic set of ions for mass calibration
that can improve the mass accuracy from some often-used calibrations by a factor of five. The effects of
extrapolation beyond the calibration range are discussed and a recommended procedure is given to
ensure that accurate mass is achieved, within a selectable uncertainty, for large molecules. Therefore, the
procedure has two parts, optimization and calibration. Subclauses 6.1 to 6.5 are only required as part of the
regular maintenance of the instrument as defined by the testing laboratory. Subclause 6.6 is required for all
calibrations of the mass scale. This is summarized in the flowchart in Figure 1.

Figure 1 — Flowchart of sequence of operations of the method
6 Method for improving mass accuracy
6.1 Obtaining the reference sample for optimization
A sample of thin (10 nm to 100 nm) PC on a flat conducting substrate (e.g. silicon wafer) shall either be
obtained or prepared, as described in 6.2.
6.2 Preparation of polycarbonate sample
6.2.1 Instructions for the preparation of a PC reference sample are provided. This method can give sample-
[2]
to-sample repeatability in ToF SIMS spectra of better than 1,9 % . To prepare such a sample for static SIMS
analysis requires a clean working environment. To reduce surface contamination, clean glassware, tweezers
and powderless gloves shall be used. The equipment required is a 1 ml glass pipette, a 100 ml glass-stoppered
measuring flask and a device for spin casting. If a device for spin casting is not available, droplet deposition
of the PC solution may be used. However, this will give poor repeatability, which will need to be carefully
taken into account during spectral analysis.
6.2.2 Using poly(bisphenol A carbonate), abbreviated to PC, weigh out 100 mg on a clean piece of
aluminium foil. Introduce the PC into the 100 ml, glass-stoppered measuring flask, add tetrahydrofuran
(THF) of analytical reagent quality to the 100 ml level line. Shake the flask to mix the PC and allow time to
dissolve it completely. This produces a 1 mg/ml solution of PC in THF. The aluminium foil shall be freshly
unrolled and the shiny surface used. Ensure that the THF is anhydrous, otherwise streaks will appear from
water when spin coating, as described in 6.2.3. The shelf life of freshly prepared stock solution shall be no
more than one month owing to water take-up.

NOTE 1 It does not matter if the PC contains low levels of additives.
NOTE 2 It does not matter if the final PC/THF solution concentration varies by ±20 %.
6.2.3 Use a conveniently sized (1 cm by 1 cm) piece of silicon, or another flat or polished conducting
substrate, and clean it overnight by soaking in propan-2-ol (isopropyl alcohol). Ultrasonically clean the
substrate in fresh propan-2-ol and dry. If an ultrasonic bath is not available, just rinse the sample in fresh
propan-2-ol. Mount the substrate on the spin casting device. Pipette approximately 0,2 ml of the PC solution
onto the substrate and spin cast at 4 000 r/min for 25 s. Samples may be prepared by depositing the PC
solution using a 5 ml pipette onto the silicon surface then air drying under ambient conditions. However, this
method will result in an uneven PC film, so care shall be taken when comparing spectra, as peak intensities
will vary.
NOTE 1 It is not essential what substrate is used, as long as it is conducting. Silicon has been found to give good-
quality films.
NOTE 2 Using this procedure, the film thickness will be approximately 10 nm. The absolute thickness is not critical.
However, if it is too thick, it is possible that the optimal SIMS spectral data is not obtained due to the charge build up
(charging).
6.3 Obtaining the SIMS spectral data
6.3.1 Insert the PC sample inside the chamber of the SIMS instrument.
6.3.2 Operate the instrument in accordance with the manufacturer's or local documented instructions.
The instrument shall have fully cooled following any bakeout. Ensure that the operation is within the
manufacturer's recommended ranges for the ion-beam current, counting rates and any other parameter
specified by the manufacturer. Check that the detector multiplier settings are correctly adjusted.
6.3.3 Select the normal analytical settings and acquisition time. For ToF instruments, select a repetition
-
rate that gives a maximum mass of at least 800 u. If the total counts in the C H O peak are less than 10 000,
9 11
increase the acquisition time to ensure that this peak contains more than 10 000 counts. It is possible that
this cannot be achieved if the signal is too weak and it is not possible to achieve 10 000 counts within a
16 2
reasonable time. To ensure that the maximum ion fluence (1 × 10 ions/m ) is not exceeded, an enlarged
raster area can be required. The acquisition time finally chosen will be a compromise between the data
quality and the duration of the work. Record the parameters set. Ensure that the detector is not saturated
using the manufacturer's or local documented instructions. This may be achieved by reducing the number of
primary ions per pulse.
NOTE For details of acquiring high-quality SIMS spectra with good repeatability and constancy, refer to
[1]
ISO 23830 .
6.4 Calculating mass accuracy
6.4.1 Instrument manufacturers' software may provide the calculation of the peak position automatically;
it is often sufficient to use this to obtain a value of M . A more accurate and reliable method for measurement
o
of the mass of
...