Energy-pooling collisions in cesium: 6PJ+6PJ→6S+(nl=7P,6D,8S,4F)

Autor: John Huennekens, Maria Allegrini, Slobodan Milošević, R. K. Namiotka, F. de Tomasi, Z. J. Jabbour
Rok vydání: 1996
Předmět:
Zdroj: Physical Review A. 54:1372-1384
ISSN: 1094-1622
1050-2947
DOI: 10.1103/physreva.54.1372
Popis: We report experimental rate coefficients for the energy-pooling collisions Cs(6{ital P}{sub 1/2})+Cs(6{ital P}{sub 1/2}){r_arrow}Cs(6{ital S}{sub 1/2})+Cs({ital nl}{sub {ital J}{prime}}) and Cs(6{ital P}{sub 3/2})+Cs(6{ital P}{sub 3/2}){r_arrow}Cs(6{ital S}{sub 1/2})+Cs({ital nl}{sub {ital J}{prime}}) where {ital nl}{sub {ital J}{prime}}=7{ital P}{sub 1/2}, 7{ital P}{sub 3/2}, 6{ital D}{sub 3/2}, 6{ital D}{sub 5/2}, 8{ital S}{sub 1/2}, 4{ital F}{sub 5/2}, or 4{ital F}{sub 7/2}. Atoms were excited to either the 6{ital P}{sub 1/2} or 6{ital P}{sub 3/2} state using a single-mode Ti:sapphire laser. The excited-atom density and spatial distribution were mapped by monitoring the absorption of a counterpropagating single-mode ring dye laser beam, tuned to either the 6{ital P}{sub 1/2}{r_arrow}8{ital S}{sub 1/2} or 6{ital P}{sub 3/2}{r_arrow}7{ital D}{sub 3/2,5/2} transitions, which could be translated parallel to the pump beam. Transmission factors, which describe the average probability that photons emitted within the fluorescence detection region can pass through the optically thick vapor without being absorbed, were calculated for all relevant transitions. Effective lifetimes of levels populated by energy-pooling collisions are modified by radiation trapping, and these factors were calculated using the Molisch theory. These calculated quantities have been combined with the measured excited-atom densities and fluorescence ratios to yield absolute energy-pooling rate coefficients. It was found that the rate formore » production, in all cases, is greatest for 6{ital D}, but that 1/2-1/2 collisions are significantly more efficient than 3/2-3/2 collisions for populating 7{ital P}. It was also found that 7{ital P}{sub 1/2} is populated two to three times more efficiently than 7{ital P}{sub 3/2} in 1/2-1/2 collisions, but that the 7{ital P} fine-structure levels are approximately equally populated in 3/2-3/2 collisions. {copyright} {ital 1996 The American Physical Society.}« less
Databáze: OpenAIRE
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