Title :

Nuclear Spin Symmetry Conservation in 1H2 16O Investigated by Direct Absorption FTIR Spectroscopy of Water Vapor Cooled Down in Supersonic Expansion

Author(s) :

Georges, Robert [Auteur correspondant]
Institut de Physique de Rennes [IPR]
Michaut, X. [Auteur]
Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique [LERMA]
Moudens, A. [Auteur]
LERMA Cergy [LERMA]
Goubet, Manuel [Auteur]
Laboratoire de Physique des Lasers, Atomes et Molécules - UMR 8523 [PhLAM]
Pirali, O. [Auteur]
Institut des Sciences Moléculaires d'Orsay [ISMO]
Soulard, P. [Auteur]
De la Molécule aux Nanos-objets : Réactivité, Interactions et Spectroscopies [MONARIS]
Asselin, P. [Auteur]
De la Molécule aux Nanos-objets : Réactivité, Interactions et Spectroscopies [MONARIS]
HUET, Therese [Auteur]
Laboratoire de Physique des Lasers, Atomes et Molécules - UMR 8523 [PhLAM]
Roy, Pascal [Auteur]
Fournier, Martin [Auteur]
Institut de Physique de Rennes [IPR]
Vigasin, A. [Auteur]
A.M.Obukhov Institute of Atmospheric Physics [IAP]

Journal title :

Journal of Physical Chemistry A

Pages :

7455-7468

Publisher :

American Chemical Society

Publication date :

2017

ISSN :

1089-5639

English keyword(s) :

Stretching
CRESU
Spin dynamics
Reservoirs (water)
Molecular physics
Water absorption
Water-molecule clustering
Vapor partial pressure
Rotational temperature
Nuclear spin isomer
Equilibrium temperatures
Water vapor
Rovibrational lines
Stretching vibrations
Supersonic expansions
Expansion
Fourier transform infrared spectroscopy
Isomers
Mixtures
Molecules
Oxygen

HAL domain(s) :

Physique [physics]
Physique [physics]/Astrophysique [astro-ph]

English abstract : [en]

We report the results of an experimental study related to the relaxation of the nuclear spin isomers of the water molecule in a supersonic expansion. Rovibrational lines of both ortho and para spin isomers were recorded ...
Show more >We report the results of an experimental study related to the relaxation of the nuclear spin isomers of the water molecule in a supersonic expansion. Rovibrational lines of both ortho and para spin isomers were recorded in the spectral range of H2O stretching vibrations at around 3700 cm-1 using FTIR direct absorption. Water vapor seeded in argon, helium, or oxygen or in a mixture of oxygen and argon was expanded into vacuum through a slit nozzle. The water vapor partial pressure in the mixture varied over a wide range from 1.5 to 102.7 hPa, corresponding to a water molar fraction varying between 0.2 and 6.5%. Depending on expansion conditions, the effect of water vapor clustering was clearly seen in some of our measured spectra. The Boltzmann plot of the line intensities allowed the H2O rotational temperatures in the isentropic core and in the lateral shear layer probed zones of the planar expansion to be determined. The study of the OPR, i.e., the ratio of the ortho to para absorption line intensities as a function of Trot, did not reveal any signs of the OPR being relaxed to the sample temperature. In contrast, the OPR was always conserved according to the stagnation reservoir equilibrium temperature. The conservation of the OPR was found irrespective of whether water molecule clustering was pronounced or not. Also, no effect of the paramagnetic oxygen admixture enhancing OPR relaxation was observed. © 2017 American Chemical Society.Show less >

Language :

Anglais

Peer reviewed article :

Oui

Audience :

Internationale

Popular science :

Non

ANR Project :

/

Collections :

• Laboratoire de Physique des Lasers, Atomes et Molécules (PhLAM) - UMR 8523

Source :

Harvested from HAL