https://doi.org/10.1007/PL00021608
Frequency measurements of hyperfine splittings in ground rovibronic states of I2 by stimulated resonant Raman spectroscopy
1
Laboratoire de Physique des Lasers, Université Paris-Nord,
Avenue J.-B. Clément, 93430 Villetaneuse, France
2
Institute of Laser Physics, Siberian Branch of the Russian Academy of Sciences,
Novosibirsk, Russia
Received:
26
September
1998
Revised:
30
November
1998
Published online: 15 April 1999
Measurements of hyperfine splittings in the ground
electronic state of have been performed by stimulated Raman
spectroscopy. An argon laser emitting at 514.5 nm, drives the
coherence between hyperfine levels of the J''=13 or J''=15
rotational levels of the ground vibronic state, via resonant
excitation of the hyperfine transitions of the optical resonances
(43-0) P(13) or R(15). We study the influence of the various
experimental parameters on the line shape: the beam geometry, the
laser modulation spectrum, the laser power, the molecular frequency
shifts. We show that only beam aberrations can give rise to a
significant asymmetry of the line shape, which contributes to an error
in the determination of the resonance frequency. From a theoretical
expression of the line shape taking into account the beam geometry, a
detailed study of this error is performed. The theoretical predictions
and the experimental results are in very good agreement. From the
measurements, improved sets of hyperfine interaction constants for the
molecule have been calculated for J''=13 and J''=15.
These constants are identical for both levels, except for quadrupole
coupling constant eqQ which exhibits a J-dependence, which we
attribute to the centrifugal distortion of the molecule.
PACS: 33.15.Pw – Fine and hyperfine structure / 33.70.Jg – Line and band widths, shapes, and shifts
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 1999