GUM’s contribution to the International Metrology in Chemistry Programme at the BIPM

1. 1 Bureau International des Poids et Mesures Bureau International des Poids et Mesures GUM’s contribution to the International Metrology in Chemistry Programme at the BIPM R. I. Wielgosz (BIPM)

2. OUTLINE OF PRESENTATION • BIPM, International Metrology, National Metrology Institutes • Visiting Scientist secondmentprogramme to the BIPM • Standards and comparisons for Atmospheric Composition: Air Quality and Greenhouse Gases • Conclusions and future outlook

3. BUREAU INTERNATIONAL DES POIDS ET MESURES The BIPM is an intergovernmental organization established by the MetreConvention, through which Member States act together on matters related to measurement science and measurement standards. www.bipm.org • The mission of the BIPM is to ensure and promote the global comparability of measurements, including providing a coherent international system of units for: • Scientific discovery and innovation, • Industrial manufacturing and international trade, • Sustaining the quality of life and the global environment. • BIPM Chemistry Department includes programmeon: • International equivalence of gas standards for air quality and climate change monitoring • Coordinating comparisons of gas standards with the National Metrology Institutes and Designated Institutes within the CCQM Gas Analysis Working Group

4. Visiting Scientists to the BIPM Chemistry Department J. Norris (NIST) 16 June – 1 Aug 2003 M. Sega (INRIM) 5 Sept – 2 Dec 2005 T. Ihara (NMIJ) 10 Oct – 10 Nov 2005 A. Rakowska (GUM) 31 Jan – 27 Apr 2006 Y. Shimitzu (NMIJ) 21 Aug – 15 Sept 2006 J. Guardado (CENAM) 30 March – 31 July 2007 C. Dazhou (NIM) 27 Aug- 20 Nov 2008 G. Ochmann (GUM) 1 Sept – 30 Nov 2008 C. Dazhou (NIM) 1 Oct – 4 Dec 2009 P. Mitchell (NMIA) 1 July - 30 Sept 2011 K. Tworek (GUM) 1 June – 30 Nov 2012 S. Lee (KRISS) 1 March – 31 May 2013 M. Lee (NIM) 1 May 2013 – 30 November 2015 C. Pascal (METAS) 1 March 2014 – 30 July 2015 D. Song (NIM) 1 June 2014 – 30 Nov 2014 M. Minarro (NPL) 1 Sept 2014 – 30 Nov 2014 B. Garrido (INMETRO) 1 Feb 2015 – 31 May 2015

5. Greenhouse and Air Quality Gases Air Quality Greenhouse Gases

6. WMO-BIPM Workshop 6 Bureau International des Poids et Mesures 2010 WMO-BIPM workshop on “Measurements Challenges for Global Observation Systems for Climate Change Monitoring’’ Signature of CIPM-MRA by WMO Wielgosz R., Calpini B., (Editors), Report on the WMO-BIPM workshop on Measurement Challenges for Global Observation Systems for Climate Change Monitoring: Traceability, Stability and Uncertainty, Rapport BIPM-2010/08, 100 pp http://www.bipm.org/en/events/wmo-bipm_workshop/

7. Establishing Traceability for Atmospheric Ozone Measurements

8. Surface Ozone Standards and Comparisons BIPM-NIST programme to maintain the comparability of the worldwide network of ozone reference standards

9. CCQM-P28 Degrees of Equivalence, Ozone mole fraction:420 nmol/mol UV Photometric Methods 2.5% bias relative to UV method GPT

10. Differences in Reference Methods for Ozone Gas Phase Titration NO + O3 NO2 + O2 NO2 primary facility (dynamic preparation) Nitrogen Monoxide Comparison CCQM-K74 (including validation of spectroscopic methods) CCQM-P73 NO (30-70) µmol/mol NO2 CCQM-P28 BIPM.QM-K1 Ozone (2-1000) nmol/mol Ozone reference standard comparison facility Progress Report (2004-2005)

11. Ozone cross-section a measurement challenge Measure O2 and other impurities, as O3 will never be “pure” (max ~99%) Lopt to be measured by interferometry Consider ozone partial pressure, as decomposition 2O3 -> 3O2 will rapidly occur

12. BIPM facility for ozone cross section measurements Mass spectrometer Large range pressure gauge High accuracy pressure gauge (Baratron) for P < 1 mbar 5 cm absorption cell Ozone generator (high voltage discharges) Temperature controlled cryostat Frequency doubled argon-ion laser with intensity stabilisation

13. Cryogenic Ozone Generator • Double walls tube in glass • Inside/outside electrodes to apply high voltage • Discharges in oxygen produce ozone • Entire system inside temperature controlled cryostat • Ozone trapped in liquid form • Pumping to remove remaining oxygen • Slow temperature increase release pure gas-phase ozone 20 kV, 50 kHz Liquid ozone trappedat 80 K

14. Absorption pathlength measurements by interferometry Michelson interferometer to deduce Lopt in the cell in which the pressure is varied Pressure in the cell: 1 bar -> 0.1 mbar -> F fringes on the photodiode -> Path length L0 n :index of refraction of air L0 / m : light path length F : number of fringes la / m : laser wavelength Edlen formula for the air index of refraction at pressure P and temperature T

15. Absorption pathlength measurements by interferometry Fringes signal on photodiode recorded with Labview: Last series of measurements Typical values Starting pressure Pi = 1012 hPa Temperature T = 22.39°C Laser l = 632.991 nm F = 42.37 fringes Giving Lopt = 4.978 cm, u(Lopt) = 0.012 cm Fringes are counted with Labview as well => most important uncertainty component

16. Absolute measurements of ozone cross-section with the UV-laser Accurate laser measurements of ozone absorption cross-sections in the Hartley band • Cryogenic ozone generator • Evaporation-condensation cycles • Impurity analysis by RGA & FTIR Ozone purity better than 99% • BIPM values in agreement with absolute measurements (in pure ozone) • Lowest uncertainty : 0.6% • Accurate laser measurements of ozone absorption cross-sections in the Hartley band. • J. Viallon , S. Lee , P. Moussay, K. Tworek , M. Petersen , R.I.Wielgosz • Submitted to Atmospheric Measurement Techniques Liquid ozone trappedat 80 K

17. NO2 standards and comparison (10ppm) CCQM GAWG key comparison on NO2 and Spectroscopic Measurements • BIPM dynamic gas standard facility for NO2 The Air Quality Strategy for England, Scotland, Wales and Northern Ireland • Objectives (for 2020) for particulate matter (PM10), nitrogen dioxide (NO2), ozone (O3), and polycyclic aromatic hydrocarbons (PAHs) are unlikely to be achieved, without further measures

18. BIPM facility for NO2 Standards 6 7 P P P P P • Flow Control System for Rubotherm • Zero air generator • NitrogenGenerator • NitrogenCylinders • molbloc (0-1000) mL/min • SAES Nitrogenpurifier • Massflowcontroller (0-100) mL/min • Massflowcontroller (0-1000) mL/min • Rubotherm System (dynamic gas mixtures) • Magneticsuspension balance • NO2permeationtube • Flow Control System for NO2 Gas Standards • Massflowcontroller (0-1000) mL/min • Multi position valve (16-ports) Rubotherm System Flow Control System for Rubotherm 8 5 9 4 V3 2 waste 1 3 V 11 V 10 waste Flow Control System for NO2 Gas Standards

19. Purity and quantification of permeating gas: Analysis by FTIR Infrared absorbance spectrum of a 150 μmol mol−1NO2/N2 gas mixture generated using the small NO2 permeation device Quantification of HNO3 without gas standards? N2O4 negligible impurity at lower concentrations

20. NO2 Permeation Rate and Impurities 20 Bureau International des Poids et Mesures • Resolution: 2 μg; • Stability,3 days: ~0.5 μg; • NO2 permeation rate, P, • (5000-10000) ng/min • u 2 ng/min xNO2- NO2 mole fraction; P - NO2 permeation rate; Vm - molar volume of nitrogen; MNO2- the molar mass of NO2; qv - total flow of nitrogen; MHNO3- the molar mass of NO3; and xHNO3 -HNO3 mole fraction measured by FTIR. • FTIR gas • facility Flores E., Idrees F., Moussay P., Viallon J., Wielgosz R., Highly Accurate Nitrogen Dioxide (NO2) in Nitrogen Standards Based on Permeation, Anal. Chem., 2012, 84(23), 10283-10290

21. HNO3 quantification using MALT 21 Bureau International des Poids et Mesures NO2 H2O Uncertainty budget for the HNO3 for mole fractions of (0.1-0.2) µmol/mol HNO3 Signal stability HITRAN database MALT-CLS

22. Uncertainty budget for NO2 standards 22 Bureau International des Poids et Mesures Accurate FT-IR spectroscopy measurements of nitrogen dioxide (NO2) and nitric acid (HNO3) calibrated with synthetic spectra, Edgar Flores*, Joële Viallon, Philippe Moussay and Robert Ian Wielgosz (APPLIED SPECTROSCOPY 67 (10), 1171-1178, 2013)

23. Results of international comparison for NO2 standards (CCQM-K74) 23 Bureau International des Poids et Mesures Value assignment of cylinders with BIPM NO2 facility (KCRV) Flores E., et al. Final report on international comparison CCQM-K74: Nitrogen dioxide, 10 µmol/mol, Metrologia, 2012, 49, Tech. Suppl., 08005 • Transfer Gas Standard NO2 mixture developed by VSL • Amount of substance fraction~10 μmol/mol • Passivatedaluminum cylinders of 5 L.

24. Conclusions and Acknowledgments • Strong collaboration and support of GUM through visiting scientists highly valued • Leads to innovation and improved international agreement of standardsat low levels of uncertainty • Important for monitoring and decision making on Air Quality and Greenhouse Gas Measurements • Many thanks to GUM and Krzysztof Tworek, GrzegorzOchmann and AgataRakowska • Future Outlook • BIPM welcomes the support of GUM for its continued programme into 2016-2019, addressing: • Carbon dioxide and Methane Standards (CCQM-K120) • Formaldehyde Standards (CCQM-K90) • Nitrogen Monoxide Standards Bureau International des Poids et Mesures