Angelos Lazoudis

Measurement of the electronic transition dipole moment by Autler-Townes splitting: Comparison of three- and four-level excitation schemes for the Na2AΣu+1−XΣg+1 system

We present a fundamentally new approach for measuring the transition dipole moment of molecular transitions, which combines the benefits of quantum interference effects, such as the Autler-Townes splitting, with the familiar R-centroid approximation. This method is superior to other experimental methods for determining the absolute value of the R-dependent electronic transition dipole moment function μe(R), since it requires only an accurate measurement of the coupling laser electric field amplitude and the determination of the Rabi frequency from an Autler-Townes split fluorescence spectral line. We illustrate this method by measuring the transition dipole moment matrix element for the Na2AΣu+1(v′=25,J′=20e)-XΣg+1(v″=38,J″=21e) rovibronic transition and compare our experimental results with our ab initio calculations. We have compared the three-level (cascade) and four-level (extended Λ) excitation schemes and found that the latter is preferable in this case for two reasons. First, this excitation scheme...

Electromagnetically induced transparency in an open V-type molecular system

We report the experimental observation of electromagnetically induced transparency (EIT) in an inhomogeneously broadened V-type Na2 molecular system. The experiment is performed with both co- and counterpropagating arrangements for the propagation directions of the coupling and probe laser beams. In our theoretical model we employ the density matrix formalism, as well as perturbative methods for obtaining the probe field absorption profile for both open and closed systems. Simulations of the experimental data show excellent agreement with the predictions derived from the basic theory. Our fluorescent intensity measurements show that, in the copropagating configuration, the EIT plus saturation window depth is about 95%, while under similar conditions in the counterpropagating geometry we observed 40%‐45% reduction in the fluorescence signal around the line center. To separate the two simultaneously occurring mechanisms in a V-type system (i.e., EIT and saturation) that are induced by the coupling field, we have carried out theoretical calculations which show that, in the copropagating case, a significant fraction of the depth of the dip is due to the coherent effect of EIT. When the coupling and probe beams are in the counterpropagating configuration, the dip is mostly due to saturation effects alone.

Hyperfine structure of the 13Δg, 2 3Πg, and 33Σg+ states of 6Li7Li

The hyperfine splittings of the 1 3Δg, 2 3Πg, and 3 3Σg+ states of 6Li7Li have been resolved by sub-Doppler, continuous wave, perturbation facilitated optical–optical double resonance excitation spectroscopy through newly identified A 1Σu+ (vA′=5, J′=24)∼b 3Πu (vb′=12, N′=23, J′=24) mixed window levels. The 3 3Σg+ and 1 3Δg states follow the case bβS coupling scheme. The Fermi contact interaction between the 7Li nucleus and the electron spin is the dominant term for the observed hyperfine splittings. The Fermi contact constants for the 7Li nucleus in the 6Li7Li molecule have been determined to be 110 MHz for the 3 3Σg+ state and 107 MHz for the 1 3Δg state. The 2 3Πg state has doubly excited character and its hyperfine coupling is different from that of the 3 3Σg+ and 1 3Δg states. The Fermi contact constants of triplet Rydberg states of 6Li7Li versus 7Li2 are discussed, and insights into the physical basis for case bβS coupling are illustrated.The hyperfine splittings of the 1 3Δg, 2 3Πg, and 3 3Σg+ states of 6Li7Li have been resolved by sub-Doppler, continuous wave, perturbation facilitated optical–optical double resonance excitation spectroscopy through newly identified A 1Σu+ (vA′=5, J′=24)∼b 3Πu (vb′=12, N′=23, J′=24) mixed window levels. The 3 3Σg+ and 1 3Δg states follow the case bβS coupling scheme. The Fermi contact interaction between the 7Li nucleus and the electron spin is the dominant term for the observed hyperfine splittings. The Fermi contact constants for the 7Li nucleus in the 6Li7Li molecule have been determined to be 110 MHz for the 3 3Σg+ state and 107 MHz for the 1 3Δg state. The 2 3Πg state has doubly excited character and its hyperfine coupling is different from that of the 3 3Σg+ and 1 3Δg states. The Fermi contact constants of triplet Rydberg states of 6Li7Li versus 7Li2 are discussed, and insights into the physical basis for case bβS coupling are illustrated.

Hyperfine structures of the 2 3Σg+, 3 3Σg+, and 4 3Σg+ states of Na2

The hyperfine structures of the 2 (3)Sigma(g) (+), 3 (3)Sigma(g) (+), and 4 (3)Sigma(g) (+) states of Na(2) have been resolved with sub-Doppler continuous wave perturbation facilitated optical-optical double resonance spectroscopy via A (1)Sigma(u) (+) approximately b (3)Pi(u) mixed intermediate levels. The hyperfine patterns of these three states are similar. The hyperfine splittings of the low rotational levels are all very close to the case b(betaS) limit. As the rotational quantum number increases, the hyperfine splittings become more complicated and the coupling cases become intermediate between cases b(betaS) and b(beta J) due to spin-rotation interaction. We present a detailed analysis of the hyperfine structures of these three (3)Sigma(g) (+) states, employing both case b(betaS) and b(beta J) coupling basis sets. The results show that the hyperfine splittings of the (3)Sigma(g) (+) states are mainly due to the Fermi-contact interaction. The Fermi contact constants for the two d sigma Rydberg states, the 2 (3)Sigma(g) (+) and 4 (3)Sigma(g) (+), are 245+/-5 MHz and 225+/-5 MHz, respectively, while the Fermi contact constant of the s sigma 3 (3)Sigma(g) (+) Rydberg state is 210+/-5 MHz. The diagonal spin-spin and spin-rotation constants, and nuclear spin-electronic spin dipolar interaction parameters of the 3 (3)Sigma(g) (+) and 4 (3)Sigma(g) (+) states are also obtained.