TY - JOUR
T1 - The ground X 1 ∑g
+ electronic state of the cesium dimer
T2 - Application of a direct potential fitting procedure
AU - Coxon, John A.
AU - Hajigeorgiou, Photos G.
PY - 2010
Y1 - 2010
N2 - A collection of 16 544 fluorescence series spectroscopic line positions involving the A 1 ∑u
+ →X 1 ∑g
+ transition in Cs2 has been analyzed by a modern direct potential fitting procedure to generate the first fully analytical potential energy function for the ground electronic state, and precise energy term values for the excited A 1 ∑u + state. The potential function yields an accurate representation of spectroscopic data that span 99.24% of the well depth and the number of fitted parameters is significantly less than half the number of parameters determined in conventional Dunham analyses. A novel variant of the Morse/long-range potential model has been employed in the representation of the ground state potential, and a critical comparison has been made with an extended modified Lennard-Jones potential model. Proper account has been taken of the known long-range van der Waals form of the potential, and our final potential function is determined with constrained literature values of the C8 and C10 dispersion energy coefficients, along with a fitted value of C6 =3.31 (5) × 107 cm-1 Å6 =6870(100) a.u. The fitted dissociation energy (De) is compared with the precisely known value based on the recent analysis of data from a two-photon transfer process (STIRAP) in ultracold Cs atoms. It is concluded that hyperfine effects in the X1 ∑g
+ state are not negligible, and that the estimate of De =3649.84 (7) cm-1 obtained in this work represents an effective dissociation limit lying between the two lowest hyperfine limits. Precise rotational and centrifugal distortion constants for the ground electronic state have also been calculated through conventional perturbation theory. These estimates are fully consistent with the derived potential function and the experimental spectroscopic information.
AB - A collection of 16 544 fluorescence series spectroscopic line positions involving the A 1 ∑u
+ →X 1 ∑g
+ transition in Cs2 has been analyzed by a modern direct potential fitting procedure to generate the first fully analytical potential energy function for the ground electronic state, and precise energy term values for the excited A 1 ∑u + state. The potential function yields an accurate representation of spectroscopic data that span 99.24% of the well depth and the number of fitted parameters is significantly less than half the number of parameters determined in conventional Dunham analyses. A novel variant of the Morse/long-range potential model has been employed in the representation of the ground state potential, and a critical comparison has been made with an extended modified Lennard-Jones potential model. Proper account has been taken of the known long-range van der Waals form of the potential, and our final potential function is determined with constrained literature values of the C8 and C10 dispersion energy coefficients, along with a fitted value of C6 =3.31 (5) × 107 cm-1 Å6 =6870(100) a.u. The fitted dissociation energy (De) is compared with the precisely known value based on the recent analysis of data from a two-photon transfer process (STIRAP) in ultracold Cs atoms. It is concluded that hyperfine effects in the X1 ∑g
+ state are not negligible, and that the estimate of De =3649.84 (7) cm-1 obtained in this work represents an effective dissociation limit lying between the two lowest hyperfine limits. Precise rotational and centrifugal distortion constants for the ground electronic state have also been calculated through conventional perturbation theory. These estimates are fully consistent with the derived potential function and the experimental spectroscopic information.
UR - http://www.scopus.com/inward/record.url?scp=77949401292&partnerID=8YFLogxK
U2 - 10.1063/1.3319739
DO - 10.1063/1.3319739
M3 - Article
C2 - 20210387
AN - SCOPUS:77949401292
SN - 0021-9606
VL - 132
JO - Journal of Chemical Physics
JF - Journal of Chemical Physics
IS - 9
M1 - 094105
ER -