High-resolution High-resolution spectroscopy of nitrous spectroscopy of nitrous acid (HONO) and its acid (HONO) and its deuterated species (DONO) deuterated species (DONO) in the far- and mid-IR in the far- and mid-IR spectral regions spectral regions A. Dehayem-Kamadjeu, A. Dehayem-Kamadjeu, J. Orphal, A. J. Orphal, A. Perrin, N. Ibrahim, I. Perrin, N. Ibrahim, I. Kleiner, and J.-M. Flaud Kleiner, and J.-M. Flaud Laboratoire Interuniversitaire des Systèmes Laboratoire Interuniversitaire des Systèmes Atmosphériques Atmosphériques CNRS UMR 7583, Universités Paris-7 et -12 CNRS UMR 7583, Universités Paris-7 et -12 Créteil / Paris, France Créteil / Paris, France
Transcript
High-resolution spectroscopy of High-resolution spectroscopy of nitrous acid (HONO) and its nitrous acid (HONO) and its
deuterated species (DONO) in the deuterated species (DONO) in the far- and mid-IR spectral regionsfar- and mid-IR spectral regions
A. Dehayem-Kamadjeu, A. Dehayem-Kamadjeu, J. Orphal, A. Perrin, N. Ibrahim, I. J. Orphal, A. Perrin, N. Ibrahim, I.
Kleiner, and J.-M. FlaudKleiner, and J.-M. Flaud
Laboratoire Interuniversitaire des Systèmes AtmosphériquesLaboratoire Interuniversitaire des Systèmes Atmosphériques
CNRS UMR 7583, Universités Paris-7 et -12CNRS UMR 7583, Universités Paris-7 et -12
Créteil / Paris, FranceCréteil / Paris, France
1. Motivation1. Motivation
Nitrous acid HONO is one of the most Nitrous acid HONO is one of the most important sources of tropospheric OH important sources of tropospheric OH radicals in the morning hoursradicals in the morning hoursHONO is formed in the troposphere by HONO is formed in the troposphere by heterogeneous reactions involving NOheterogeneous reactions involving NOxx
However its sources are currently not well However its sources are currently not well understood (huge differences wrt. models)understood (huge differences wrt. models)Spectroscopic studies are useful both in Spectroscopic studies are useful both in the laboratory and in the field the laboratory and in the field
2. Previous IR studies2. Previous IR studies
Previous IR studies of HONO (Previous IR studies of HONO (transtrans / / ciscis))– Deeley and Mills, 1983-1985 Deeley and Mills, 1983-1985 – Guilmot, Herman et al., 1991-1993Guilmot, Herman et al., 1991-1993– most of the six IR fundamental bands have most of the six IR fundamental bands have
been analyzed for been analyzed for transtrans-HONO -HONO – for for ciscis-HONO some bands are missing-HONO some bands are missing
DONO has been studied at high resolution DONO has been studied at high resolution too but only a few IR bands too but only a few IR bands No far-infrared rotational spectra (but MW)No far-infrared rotational spectra (but MW)
3. This work3. This work
First far-infrared rotational spectra of First far-infrared rotational spectra of transtrans- and - and ciscis-HONO (and -DONO) -HONO (and -DONO)
First high-resolution spectra of the First high-resolution spectra of the 11 bands of bands of trans-trans- and and ciscis-DONO -DONO
Re-analysis of the Coriolis-interacting Re-analysis of the Coriolis-interacting 55//66 bands of bands of transtrans-HONO around 16 -HONO around 16 mmAb-initioAb-initio calculations, semi-experimental calculations, semi-experimental and equilbrium structures of HONO (with and equilbrium structures of HONO (with J. Demaison, Lille, see Prague 2006)J. Demaison, Lille, see Prague 2006)
Far-infrared spectra:Far-infrared spectra:– White cell made of Pyrex glass, path 800 cm, White cell made of Pyrex glass, path 800 cm,
windows made of polyethylene, free spectral windows made of polyethylene, free spectral range 20-700 cmrange 20-700 cm-1-1, He cooled bolometer, He cooled bolometer
Mid-infrared spectra:Mid-infrared spectra:– Pyrex cell, path 300 cm, CaFPyrex cell, path 300 cm, CaF22 windows windows
Synthesis: HSynthesis: H22O + NO + NOO + NO + NO22 mixtures mixtures
5. Far-infrared spectra5. Far-infrared spectra
Overview of the far-IR part (rotational lines)Overview of the far-IR part (rotational lines)
