High accuracy transition intensities for ozone
Lead Research Organisation:
University College London
Department Name: Physics and Astronomy
Abstract
Ozone is present in low concentrations throughout the Earth's atmosphere. In the troposphere ozone is a pollutant which largely results from human activity. However, ozone is harmful to humans, animals and plants at even trace concentrations. Conversely stratospheric ozone, the ``ozone layer'', provides an extremely important shield of solar ultraviolet radiation. Human activity has resulted in a significant reduction in stratospheric ozone and this loss has lead to increased holes at the poles.
Studies of atmospheric ozone concentrations rely heavily on the use of spectroscopic remote sensing from a mixture of ground-based, airborne and satellite instruments. These instruments observe the characteristic absorption features of ozone either in the infrared or the ultraviolet. Retrievals based on these observations require accurate laboratory data to make them useful. In particular the many studies of atmospheric currently being conducted require intensity / cross section data for both ultraviolet (UV) and infrared (IR) which is accurate to 1% or better.
Unfortunately, as has been extensively documented in the scientific literature, the situation with the laboratory intensity determinations is far from satisfactory. Firstly, there are many measurements showing systematic differences between atmospheric studies performed at infrared and ultraviolet wavelengths at the 4 to 5 % level. Secondly, while laboratory measurements of the ultraviolet cross sections show a measure of agreement, those for the infrared do not. A recent (2012) analysis concluded that for the key 10 micron region agreement between measurements was only at best 4% with intensity discrepancies much higher than this. There are other discrepancies within the infrared region. There is an urgent need for a solution to this problem for missions such as TES+OMI on Aura satellite mission (NASA), IASI+GOME-2 on Metop satellite (ESA) AIRS on the Auqa satellite (NASA).
The proposal will use high accuracy, first principles quantum mechanical methods to compute the transition intensities for both the IR and UV portions of the spectrum. For the IR region, methods of computing high accuracy dipole moment surfaces already used successful for water and CO2, will be employed. These will be combined with measured transition frequencies to complete line lists with intensities accurate to about 0.5%.
New methodologies will be developed to transfer the experience gained computing IR vibration-rotation intensities (which require electronically diagonal dipole moments) to electronic transitions in the UV. Initial work will focus on the Huggins band and will also require further development of the methods used for treating nuclear motion.
These calculations will provide complete independent assessment of the absolute line intensities / cross sections removed from experimental issues such as the ozone concentration. Results will be made widely available via the web, databases and submitted for inclusion in standard compilations used for atmospheric studies such as HITRAN. HITRAN will be a project partner on the proposal and undertake independent evaluation of the results.
Studies of atmospheric ozone concentrations rely heavily on the use of spectroscopic remote sensing from a mixture of ground-based, airborne and satellite instruments. These instruments observe the characteristic absorption features of ozone either in the infrared or the ultraviolet. Retrievals based on these observations require accurate laboratory data to make them useful. In particular the many studies of atmospheric currently being conducted require intensity / cross section data for both ultraviolet (UV) and infrared (IR) which is accurate to 1% or better.
Unfortunately, as has been extensively documented in the scientific literature, the situation with the laboratory intensity determinations is far from satisfactory. Firstly, there are many measurements showing systematic differences between atmospheric studies performed at infrared and ultraviolet wavelengths at the 4 to 5 % level. Secondly, while laboratory measurements of the ultraviolet cross sections show a measure of agreement, those for the infrared do not. A recent (2012) analysis concluded that for the key 10 micron region agreement between measurements was only at best 4% with intensity discrepancies much higher than this. There are other discrepancies within the infrared region. There is an urgent need for a solution to this problem for missions such as TES+OMI on Aura satellite mission (NASA), IASI+GOME-2 on Metop satellite (ESA) AIRS on the Auqa satellite (NASA).
The proposal will use high accuracy, first principles quantum mechanical methods to compute the transition intensities for both the IR and UV portions of the spectrum. For the IR region, methods of computing high accuracy dipole moment surfaces already used successful for water and CO2, will be employed. These will be combined with measured transition frequencies to complete line lists with intensities accurate to about 0.5%.
New methodologies will be developed to transfer the experience gained computing IR vibration-rotation intensities (which require electronically diagonal dipole moments) to electronic transitions in the UV. Initial work will focus on the Huggins band and will also require further development of the methods used for treating nuclear motion.
These calculations will provide complete independent assessment of the absolute line intensities / cross sections removed from experimental issues such as the ozone concentration. Results will be made widely available via the web, databases and submitted for inclusion in standard compilations used for atmospheric studies such as HITRAN. HITRAN will be a project partner on the proposal and undertake independent evaluation of the results.
Planned Impact
There is considerable interest in accurate line lists from the non-academic community. Besides the needs of the atmospheric remote sensing community (discussed under academic beneficiaries), there are many others involved in environmental monitoring. For example we have a collaboration with Servomex plc. Servomex undertakes gas analysis for hydrocarbon processing, industrial gas production and respiratory medicine markets. They are very interested in using line lists generated by my group at UCL for work in optimising their products.
The line intensities (and associated line list) generated in this project will be distributed widely and vigorously to maximise
its potential impact. It will be made available via (atmospheric) databases HITRAN and GEISA; via BADC and via
web portals such as the Virtual Atomic and Molecular Data Centre (VAMDC), and my own exomol.com website.
My work on molecular spectroscopy regularly gets extensive national and international press coverage. I use topics from
this work (including ones relating to atmospheric physics) as the basis of popular talks which I give to schools and other
non-specialist groups.
The line intensities (and associated line list) generated in this project will be distributed widely and vigorously to maximise
its potential impact. It will be made available via (atmospheric) databases HITRAN and GEISA; via BADC and via
web portals such as the Virtual Atomic and Molecular Data Centre (VAMDC), and my own exomol.com website.
My work on molecular spectroscopy regularly gets extensive national and international press coverage. I use topics from
this work (including ones relating to atmospheric physics) as the basis of popular talks which I give to schools and other
non-specialist groups.
Publications
Mizus II
(2018)
High-accuracy water potential energy surface for the calculation of infrared spectra.
in Philosophical transactions. Series A, Mathematical, physical, and engineering sciences
Polyansky O
(2016)
Calculation of rotation-vibration energy levels of the ammonia molecule based on an ab initio potential energy surface
in Journal of Molecular Spectroscopy
Polyansky O
(2018)
Potential energy surface, dipole moment surface and the intensity calculations for the 10 µm, 5 µm and 3 µm bands of ozone
in Journal of Quantitative Spectroscopy and Radiative Transfer
Polyansky O
(2021)
Variational analysis of HF dimer tunneling rotational spectra using an ab initio potential energy surface
in Journal of Molecular Spectroscopy
Qu Q
(2021)
ExoMol molecular line lists - XLII. Rovibronic molecular line list for the low-lying states of NO
in Monthly Notices of the Royal Astronomical Society
Rutkowski L
(2018)
An experimental water line list at 1950 K in the 6250-6670 cm - 1 region
in Journal of Quantitative Spectroscopy and Radiative Transfer
Shuo Huang
(2016)
OPTIMIZING REMOTE PLASMA SOURCES FOR SELECTIVE ETCHING
in 2016 43RD IEEE INTERNATIONAL CONFERENCE ON PLASMA SCIENCE (ICOPS)
Simkó I
(2017)
Recommended Ideal-Gas Thermochemical Functions for Heavy Water and its Substituent Isotopologues
in Journal of Physical and Chemical Reference Data
Sousa-Silva C
(2015)
ExoMol line lists - VII. The rotation-vibration spectrum of phosphine up to 1500 K
in Monthly Notices of the Royal Astronomical Society
Tennyson J
(2016)
The ab initio calculation of spectra of open shell diatomic molecules
in Journal of Physics B: Atomic, Molecular and Optical Physics
Tennyson J
(2020)
The 2020 release of the ExoMol database: Molecular line lists for exoplanet and other hot atmospheres
in Journal of Quantitative Spectroscopy and Radiative Transfer
Tennyson Jonathan
(2015)
Molecular line lists of carbon-containing molecules for exoplanets and other hot bodies
in ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY
Tennyson Jonathan
(2021)
ExoMol at 10
in ASTRONOMY & GEOPHYSICS
Tennyson Jonathan
(2018)
The ExoMol atlas of cool star and exoplanet molecular opacities
in ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY
Wang Y
(2017)
MAX-DOAS measurements of HONO slant column densities during the MAD-CAT campaign: inter-comparison, sensitivity studies on spectral analysis settings, and error budget
in Atmospheric Measurement Techniques
Zak EJ
(2017)
Ro-vibronic transition intensities for triatomic molecules from the exact kinetic energy operator; electronic spectrum for the C~ 1B2 ? X~ 1A1 transition in SO2.
in The Journal of chemical physics
Zobov N
(2018)
Analysis of the red and green optical absorption spectrum of gas phase ammonia
in Journal of Quantitative Spectroscopy and Radiative Transfer
Zobov Nikolai F.
(2018)
Analysis of the red and green optical absorption spectrum of gas phase ammonia
in JOURNAL OF QUANTITATIVE SPECTROSCOPY & RADIATIVE TRANSFER
Description | We have managed to reconcile the absorption of ozone in key sectors of the infra red. |
Exploitation Route | Yes. We are currently having them tested by a modeller at JPL, USA. If things are successful the results will be submitted for inclusion in databases such as HITRAN. |
Sectors | Environment |
Description | Data has been used as part of the evaluation of the ozone problem by HITRAN |
First Year Of Impact | 2018 |
Sector | Aerospace, Defence and Marine,Environment |
Impact Types | Policy & public services |
Description | HITRAN database |
Organisation | Harvard University |
Department | Harvard-Smithsonian Center for Astrophysics |
Country | United States |
Sector | Academic/University |
PI Contribution | The HITRAN database is run from the Harvard-Smithson Center for Astrophysics, USA. We are major contributors to the database. |
Collaborator Contribution | They evaluate data and include it in the database. |
Impact | The HITRAN database is a common output plus associated publication every 4 years. |
Description | Infrared absorption by ozone |
Organisation | Sorbonne University |
Country | France |
Sector | Academic/University |
PI Contribution | We provided theoretical data for analysis of the experiments. |
Collaborator Contribution | Novel, high accuracy experimental data. |
Impact | Joint paper just submitted. |
Start Year | 2020 |
Title | DVR3D update |
Description | The DVR3D package was extended to consider rovibronic transition intensities |
Type Of Technology | Software |
Year Produced | 2017 |
Open Source License? | Yes |
Impact | This has allowed the study of uv transitions of atmospheric molecules |
URL | https://github.com/ExoMol/dvr3d |