Bureau International des Poids et Mesures WMO Ozone Theme meeting Geneva, 11-13 May 2009 Bureau International des Poids et Mesures Requirements for new measurements of ozone absorption cross-sections for the accurate determination of ozone concentration J. Viallon , P. Moussay, M. Petersen and R.I. Wielgosz, Bureau International des Poids et Mesures
26
Embed
Requirements for new measurements of ozone absorption ...igaco-o3.fmi.fi/ACSO/presentations_2009/laboratory/Viallon.pdf · others such as the SI Brochure. CIPM 1894 CIPM 2007. WMO
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Bureau International des Poids et Mesures
WMO Ozone Theme meeting
Geneva, 11-13 May 2009
Bureau International des Poids et Mesures
Requirements for new measurements of ozone
absorption cross-sections for the accurate
determination of ozone concentration
J. Viallon, P. Moussay, M. Petersen and R.I. Wielgosz,
Bureau International des Poids et Mesures
WMO Ozone Theme meeting, Geneva, 11-13 May 2009
Outline
The CIPM, the BIPM, the chemistry section
International comparisons of ozone standards
Scientific programme (1) : biases in the reference standard
Scientific programme (2) : biases in the reference method
Future programme : new measurements of the ozone absorption
cross-section
WMO Ozone Theme meeting, Geneva, 11-13 May 2009
BUREAU INTERNATIONAL DES POIDS ET MESURES
The BIPM
It has headquarters near Paris, France. It is financedjointly by the Member States and Associates, and operates under the exclusive supervision of the CIPM.
Its mandate is to provide the basis for a single, coherent system of measurements throughout the world, traceable to the International System of Units (SI). This task takes many forms, from direct dissemination of units (as in the case of mass and time) to coordination through international comparisons of national measurement standards (as in length, electricity and ionizing radiation).
It maintains scientific laboratories in areas of: mass, time, frequency and gravimetry, electricity,ionizing radiation, and chemistry.
It has an international staff of over 70 and its statusvis-à-vis the French Government is similar to that ofother intergovernmental organizations.
Its budget is over eleven million euros.
WMO Ozone Theme meeting, Geneva, 11-13 May 2009
COMITÉ INTERNATIONAL DES POIDS ET MESURES
The CIPM
Is made up of eighteen individuals, each from a different State. Its principal task
is to promote worldwide uniformity in units of measurement by direct action
or by submitting draft resolutions to the CGPM.
Meets annually and, its duties include:
consideration of the work of the BIPM;
consideration of reports presented to it by its Consultative Committees;
consideration of metrological work that Member Statesdecide to do in common and sets up and coordinatesactivities between specialists in metrology;
making appropriate Recommendations;
issuing an Annual Report on the administrative andfinancial position of the BIPM to the Member States;
commissioning reports in preparation for CGPMs, andothers such as the SI Brochure.
CIPM 1894
CIPM 2007
WMO Ozone Theme meeting, Geneva, 11-13 May 2009
Chemical metrology is important in national measurement infrastructures
to improve industrial competitiveness, facilitate trade, implement
regulations, ensure the safety of products, protect the environment and
enhance the quality of life.
The BIPM organizes international comparisons of:
gas standards for air quality and greenhouse gas monitoring;
and of primary calibrators for laboratory medicine, food analysis and forensics.
The BIPM maintains a central O3 reference standard comparison facility,
facilities for NO and NO2 gas standard comparisons, and is developing
facilities for CH4 and CH2O gas standard comparisons.
The BIPM is coordinating comparisons on the purity of monitored therapeutic drugs and steroid hormones to underpin reference
measurement systems for clinical analytes. Future comparisons will
underpin systems for contaminants and residues in food as well as
forensic applications.
The BIPM maintains the database of the Joint Committee on Traceability in Laboratory Medicine, which lists certified
reference materials and methods of higher order which have been
reviewed by the Committee against ISO standards.
CHEMISTRY
WMO Ozone Theme meeting, Geneva, 11-13 May 2009
Gas Metrology Programme (2005-2008)
1000 1100 1600 1700 1800 1900
0.000
0.005
0.010
GPT Products
wavenumber / cm-1
0.000
0.005
0.010
fitted spectrum
(HITRAN/MALT/CLS)
measured spectrum
(p, T ambient, 1 cm-1, 6.4 m cell)GPT Reactants
Absorb
ance
NO21.0 µmol mol-1
O31.0 µmol mol-1
NO2.6 µmol mol-1
Ozone reference standard
comparison facility
NO2 primary facility (dynamic preparation)
NO standard comparison facilityCCQM-P28
BIPM.QM-K1
Ozone (2-1000) nmol/mol
Method development
and validation at
10 µmol/mol
CCQM-P73
NO (30-70) µmol/mol
Gas Phase Titration
NO + O3 →→→→ NO2 + O2
Laser based SRP
WMO Ozone Theme meeting, Geneva, 11-13 May 2009
1000 1100 1600 1700 1800 1900
0.000
0.005
0.010
GPT Products
wavenumber / cm-1
0.000
0.005
0.010
fitted spectrum
(HITRAN/MALT/CLS)
measured spectrum
(p, T ambient, 1 cm-1
, 6.4 m cell)GPT Reactants
Ab
so
rba
nce
Gas Metrology Programme (2009-2012)
Ozone reference standard
comparison facility BIPM.QM-K1Ozone (2-1000)
nmol/mol
Gas Phase Titration CCQM-P110
NO2 /N2 10 µmol/mol
O3 absorption cross section
240 245 250 255 260 265 270
80
90
100
110
120
Arg
on laser
Arg
on laser
Arg
on laser
YA
G laser
cro
ss-s
ectio
n /
10
-19 c
m2 .m
ole
cu
les
-1
λ / nm
294K, Hearn 61
298K, Daumont 92
295K, Bass &Paur 81
295K, Yoshino & al. 93
250K, Bass 81
298K, Molina 86
αO3
Core ComparisonCH4 / air
Analytical Challenge Comparison
CH2O 10 µmol/mol
Green House Gas comparison facility
Formaldehyde (ozone precursor)
facility
WMO Ozone Theme meeting, Geneva, 11-13 May 2009
Outline
The CIPM, the BIPM, the chemistry section
International comparisons of ozone standards
Scientific programme (1) : biases in the reference standard
Scientific programme (2) : biases in the reference method
Future programme : new measurements of the ozone absorption
cross-section
WMO Ozone Theme meeting, Geneva, 11-13 May 2009
The reference method for ozone at ambient level:UV photometry
BIPM – SRP27
OZONE SAMPLEOZONE SAMPLE
LIGHT
INTENSITY I0
ATTENUATED LIGHT
INTENSITY I
Light Path length 2l
σσσσ Ozone absorption cross-section at 253.64 nm under standard conditions of temperature and pressure
T Temperature in the cells
P Pressure in the cells
R Gas constant
NA Avogadro constant
D Product of transmittance of the two
cellsLopt light path length
1ln( )
2 opt A
T Rx D
L P Nσ
−=
x mole fraction of ozone in dry air (nmol/mol)
WMO Ozone Theme meeting, Geneva, 11-13 May 2009
Scheme for international comparisons
BIPM-SRP27
National standardWMO/GAW World Calibration
Centre (EMPA)Regional networks calibration centre
National station WMO/GAW station Regional station
Stations around the world monitoring ozone at ambient level….
Chain of regular calibrations
Regular comparisons (or calibrations)
WMO Ozone Theme meeting, Geneva, 11-13 May 2009
SRP27 (reference)
SRP28 SRP31
Comparisons at the BIPM
Triad of Triad of SRPsSRPs maintained at the BIPM maintained at the BIPM
One comparison = 2 ozone standards measuring different O3 concentration from the