43 research outputs found
The states 1^1\Sigma^+_u, 1^1\Pi_u and 2^1\Sigma^+_u of Sr_2 studied by Fourier-transform spectroscopy
A high resolution study of the electronic states 1^1\Sigma^+_u and 1^1\Pi_u
which belong to the asymptote 4^1D + 5^1S and of the state 2(A)^1\Sigma^+_u,
which correlates to the asymptote 5^1P + 5^1S, is performed by
Fourier-transform spectroscopy of fluorescence progressions induced by single
frequency laser excitation. Precise descriptions of the potentials up to 2000
cm^{-1} above the bottom are derived and compared to currently available ab
initio calculations. Especially for the state 1^1\Sigma^+_u large deviations
are found. Rather weak and local perturbations are observed for the states
1^1\Pi_u and 2^1\Sigma^+_u, while a strong coupling of the state 1^1\Sigma^+_u
to the component \Omega=0^+_u of the state 1^3\Pi_u, which belongs to the
asymptote 5^3P + 5^1S, is indicated.Comment: Typing errors corrected (including numbers in table IX), 12 pages, 9
figure
Study of the Born-Oppenheimer Approximation for Mass-Scaling of Cold Collision Properties
Asymptotic levels of the A state of the two isotopomers
and up to the dissociation limit
are investigated with a Doppler-free high resolution laser-spectroscopic
experiment in a molecular beam. The observed level structure can be reproduced
correctly only if a mass dependent correction term is introduced for the
interaction potential. The applied relative correction in the depth of the
potential is , which is in the order of magnitude expected for
corrections of the Born-Oppenheimer approximation. A similar change in ground
state potentials might lead to significant changes of mass-scaled properties
describing cold collisions like the s-wave scattering length.Comment: 8 pages, 6 figure
Mixing of 0(+) and 0(-) observed in the hyperfine and Zeeman structure of ultracold Rb-2 molecules
We study the combination of the hyperfine and Zeeman structure in the spin-orbit coupled A(1)Sigma(+)(u) = b(3)Pi(u) complex of Rb-87(2). For this purpose, absorption spectroscopy at a magnetic field around B = 1000 G is carried out. We drive optical dipole transitions from the lowest rotational state of an ultracold Feshbach molecule to various vibrational levels with 0(+) symmetry of the A - b complex. In contrast to previous measurements with rotationally excited alkali-dimers, we do not observe equal spacings of the hyperfine levels. In addition, the spectra vary substantially for different vibrational quantum numbers, and exhibit large splittings of up to 160 MHz, unexpected for 0(+) states. The level structure is explained to be a result of the repulsion between the states 0(+) and 0(-) of b(3)Pi(u), coupled via hyperfine and Zeeman interactions. In general, 0(-) and 0(+) have a spin-orbit induced energy spacing Delta, that is different for the individual vibrational states. From each measured spectrum we are able to extract Delta, which otherwise is not easily accessible in conventional spectroscopy schemes. We obtain values of Delta in the range of +/- 100 GHz which can be described by coupled channel calculations if a spin-orbit coupling is introduced that is different for 0(-) and 0(+) of b(3)Pi(u).DFGMinistry of Science and Culture of Lower Saxony, German