Study of velocity-changing collisions by time resolved saturated absorption

Gorlicki, M.; Peuriot, A.; Dumont, Michel

doi:10.1051/jphyslet:019800041012027500

Cited by 19 publications

(9 citation statements)

References 11 publications

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“…Suivant On peut ainsi remonter a differents parametres caract6ristiques de ces collisions : sections efficaces de collision [7], parametres de conservation de l'observable etudiee lors de la collision, noyau integral de collision [8,9,10,11,12] resonnante avec les atomes dont la vitesse tombe dans la bande hachuree dD. La figure la represente le cas ou la frequence du laser n'est pas exactement centree sur la resonance atomique : les domaines dp et dD ne se recouvrent donc pas.…”

Section: Classificationunclassified

Pompage optique doublement sélectif en vitesses

1982

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Section: Classificationunclassified

Pompage optique doublement sélectif en vitesses

1982

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“…In our experiments we used a transient method previously described, 7 which has been improved to allow the recording of the saturation line shape after a very short time delay following the switching on of the saturating beam. Thus, the observed signal is the result of only one collision per atom.…”

Section: Elastic Collision Kernels: Theoretical Determination and Dirmentioning

confidence: 99%

“…In addition, the existence of the narrow peak of the direct kernel has been demonstrated previously by the observation of the broadening of the saturation peak as a function of time. 7 One major question, which will be discussed elsewhere, is the sensitivity of the kernel to the shape of the differential cross section. Preliminary calculations have shown that different test functions, for the differential cross section, produce very different kernels which would be in contradiction with the experiments.…”

Section: Elastic Collision Kernels: Theoretical Determination and Dirmentioning

confidence: 99%

Elastic Collision Kernels: Theoretical Determination and Direct Observation by Use of Time-Resolved Saturation Spectroscopy in Metastable Neon

1982

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Collision kernels describing elastic collision effects in saturation spectroscopy are completely calculated for the metastable 3 P 0 state of neon, starting from true experiment-deduced potentials. Collision processes with and without metastability exchange are respectively considered. A direct observation of these two kernels is provided by a two-laser time-resolved saturated absorption experiment. They are in good agreement with theory.PACS numbers: 34.40.+n, 32.70.Jz Line shapes in saturation spectroscopy are strongly affected by collisions. As in linear spectroscopy they are sensitive to quenching collisions and to dephasing collisions (broadening and shift), but in addition, as was pointed out early on, they are sensitive to velocity changing collisions (VCC). Many theoretical and experimental works have been devoted to this subject.The quantity of interest is the collision kernel W(v'-*v) which describes the probability per unit time that a collision will change the projection of the atomic velocity on the laser beam axis from v' to v. Many theoretical papers deal with the formal determination of the kernel from scattering amplitudes (sometimes from the interatomic potentials) and with the evaluation of the line shape from the kernel. 1 " 5 Nevertheless in all detailed calculations of line shapes phenomenological potentials (hard sphere, 3 R" 6 , 5 Lennard-Jones) or phenomenological kernels (Keilson and Storer 6 ) are used. In this paper, we present the first attempt to link all the steps from a realistic potential to a direct experimental observation of the kernel. The metastable 3 P 0 level of neon (ls 3 in Paschen notation) has been considered, since the Ne*-Ne potentials had been calculated and the differential cross sections measured.Experimentally the situation is comparable: Many experiments have been performed, but they have been interpreted with phenomenological kernels (strong or weak collisions 6 ). Furthermore in several cases the observed background (strong collisions) or the broadening of saturation peaks (weak collisions) is actually produced by several collisions for each atom and does not clearly represent the kernel.In our experiments we used a transient method previously described, 7 which has been improved to allow the recording of the saturation line shape after a very short time delay following the switching on of the saturating beam. Thus, the observed signal is the result of only one collision per atom. Another novel feature of this work lies in the calculation of a metastability exchange kernel and in its experimental observation in a mixture of two isotopes.Because of its short lifetime, the upper level of the transition (2p 2 for the 613.3-nm line or 2/> 5 for the 626.6-nm line) provides a negligible contribution to the saturation signal. On the other hand, when a collision changes the velocity of an atom that is in a coherent superposition of both levels, this coherence is destroyed, since very different interatomic potentials are involved 8 (except for very small scattering angl...

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“…The dye-laser frequency is stabilized by means of a Fabry-Pe*rot interferometer (stability ~1 MHz), and locked to the chosen neon line by means of a saturated absorption Ne cell. 12 The light beam crosses the metastable atom beam at right angle, 1 cm before the collision point. In order to improve the efficiency of the optical pumping, the laser beam crosses twice the atomic beam and its convergence has been matched to the slight divergence of the atomic beam (-1.5°).…”

Section: Fine-structure Transition In Ne( 3 P 0 ) On Neoso) Collisionmentioning

confidence: 99%

Fine-Structure Transition in Ne(P03) on Ne(
Daunant
¹
,
Vassilev
²
,
Dumont
³

et al. 1981
Phys. Rev. Lett.
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The co His ion-induced exothermic fine-structure transition Ne( 3 P 0 )-Ne( 3 P 2 ) has been observed in a crossed-effusive-beam experiment, by measuring the time of flight of metastable atoms scattered perpendicularly to the incident-beam plane. In this direction, the elastic scattering is kinematically discriminated. The identification of the transition is achieved by pumping 3 P 0 or 3 P 2 levels with a cw dye laser.

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Study of velocity-changing collisions by time resolved saturated absorption

Cited by 19 publications

References 11 publications

Pompage optique doublement sélectif en vitesses

Pompage optique doublement sélectif en vitesses

Elastic Collision Kernels: Theoretical Determination and Direct Observation by Use of Time-Resolved Saturation Spectroscopy in Metastable Neon

Fine-Structure Transition in Ne(P03) on Ne(
Daunant
¹
,
Vassilev
²
,
Dumont
³

et al. 1981
Phys. Rev. Lett.
Self Cite
14
0
4
0
View full text Add to dashboard Cite

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Study of velocity-changing collisions by time resolved saturated absorption

Cited by 19 publications

References 11 publications

Pompage optique doublement sélectif en vitesses

Pompage optique doublement sélectif en vitesses

Elastic Collision Kernels: Theoretical Determination and Direct Observation by Use of Time-Resolved Saturation Spectroscopy in Metastable Neon

Fine-Structure Transition in Ne(P03) on Ne(Daunant1, Vassilev2, Dumont3 et al. 1981Phys. Rev. Lett.Self Cite14040View full textAdd to dashboardCite

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Fine-Structure Transition in Ne(P03) on Ne(
Daunant
¹
,
Vassilev
²
,
Dumont
³

et al. 1981
Phys. Rev. Lett.
Self Cite
14
0
4
0
View full text Add to dashboard Cite