Radiative transition probabilities and lifetimes for the band systems A²pi - X²sigma+ of the isovalent molecules BeF, MgF and CaF

Pelegrini, Marina; Vivacqua, Ciro S.; Roberto‐Neto, Orlando; Ornellas, Fernando R.; Machado, Francisco B. C.

doi:10.1590/s0103-97332005000600007

Cited by 42 publications

(58 citation statements)

References 22 publications

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“…This information, together with the table of branching ratios given in [43] provides an estimated value of Z = 0.91 ± 0.05. A high value for Z is to be expected since YbF closely resembles the alkaline-earth monofluorides which all have this property [45]. Finally then, we take r ≈ 0.23 for this experiment.…”

Section: Molecule Density and Saturation Of The Absorptionmentioning

confidence: 99%

Diffusion, thermalization, and optical pumping of YbF molecules in a cold buffer-gas cell

et al. 2011

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We produce YbF molecules with a density of 10 18 m −3 using laser ablation inside a cryogenicallycooled cell filled with a helium buffer gas. Using absorption imaging and absorption spectroscopy we study the formation, diffusion, thermalization and optical pumping of the molecules. The absorption images show an initial rapid expansion of molecules away from the ablation target followed by a much slower diffusion to the cell walls. We study how the time constant for diffusion depends on the helium density and temperature, and obtain values for the YbF-He diffusion cross-section at two different temperatures. We measure the translational and rotational temperatures of the molecules as a function of time since formation, obtain the characteristic time constant for the molecules to thermalize with the cell walls, and elucidate the process responsible for limiting this thermalization rate. Finally, we make a detailed study of how the absorption of the probe laser saturates as its intensity increases, showing that the saturation intensity is proportional to the helium density. We use this to estimate collision rates and the density of molecules in the cell.

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Section: Molecule Density and Saturation Of The Absorptionmentioning

confidence: 99%

Diffusion, thermalization, and optical pumping of YbF molecules in a cold buffer-gas cell

et al. 2011

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“…14 Hz rad [30]) are reduced by a factor r T = 0.90, those associated with rotational transitions (ω 10 = 1.32×10…”

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confidence: 99%

Thermal Casimir versus Casimir-Polder Forces: Equilibrium and Nonequilibrium Forces

2008

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We critically discuss whether and under what conditions Lifshitz theory may be used to describe thermal Casimir-Polder forces on atoms or molecules. An exact treatment of the atom-field coupling reveals that for a ground-state atom (molecule), terms associated with virtual-photon absorption lead to a deviation from the traditional Lifshitz result; they are identified as a signature of non-equilibrium dynamics. Even the equilibrium force on a thermalized atom (molecule) may be overestimated when using the ground-state polarizability instead of its thermal counterpart. In all of these areas, a thorough understanding of dispersion forces under realistic conditions must account for their temperature dependence induced by thermal photons [6]. A series of high-precision experiments [7] has triggered a renewed interest in this thermal Casimir force [8] by opening the perspective of its experimental investigation [9]. It was noticed that, depending on the model chosen to describe the metal response, Lifshitz theory can yield different answers for the temperature dependence of the Casimir energy between two metal plates [10]. The resulting debate concerning the correct description of the thermal Casimir force [11] will ultimately have to be settled by experiments. Non-equilibrium situations of two plates of different temperatures have recently been suggested as sensitive probes to the quantum electrodynamics (QED) of the Casimir effect [12].The CP force on single atoms can be measured indirectly via spectroscopic means; clear evidence for thermal frequency shifts has been found for atoms inside a cavity [13] and their signature has been detected in the interaction of atoms with a sapphire surface [14]. The novel non-equilibrium CP forces predicted for the case of different surface and environment temperatures [15] have recently been observed via their effect on the centerof-mass oscillations of a trapped Bose-Einstein condensate [16]. While some theoretical studies of the thermal CP force are based on a QED treatment of the atomfield coupling [17,18], the vast majority of investigations invokes a macroscopic calculation using Lifshitz theory [6,19,20] or a linear-response description of the atom [15,21] (leading to equivalent results).The macroscopic approach to the CP force is based on a very close relation between Casimir and CP forces. It is the validity of this one-to-one correspondence and its results for the CP force that we intend to investigate in this Letter, so let us briefly recount the argument in its traditional form: Generalizing the famous Lifshitz result for two plates [6], the thermal Casimir force on a homogeneous body of arbitrary shape occupying a volume V in free space due to the presence of another body can be given as a Matsubara sum [22,23] with Matsubara frequencies ξ N = 2πk B T N/ . Here, Gis the scattering part of the classical Green tensorassociated with the bodies that are characterized by their dielectric permittivity ε(r, ω). The result (1) can be obtained from the zero-temperature force b...

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“…PG describes A 2 П -X 2 Σ + as a strong system appearing in the wavelength region between 368.6 nm and 346. The Franck-Condon factors (FCFs) for the transitions between low-lying vibrational levels of the B 1 Σ + and X 1 Σ + electronic states were calculated by Singh et al [31], based on the experimental results by Barrow and Beale [28], and also in an extensive theoretical ab initio study by Pelegrini et al [32]. The broad peaks with the maxima at 359.42 nm and 350.34 nm in our spectrum presented in Fig.…”

Section: Spectroscopic Characterization Of Peo Processmentioning

confidence: 70%

“…Singh et al [31] used in their calculations the equilibrium bond length of 1.733 Å for the A 2 П state, much differing from the value quoted by HH (1.7469 Å [23]) -see also Table 1 of Ref. [32]. This difference significantly influences the results for FCFs.…”

Section: Estimation Of Temperature From Intensity Distribution Withinmentioning

confidence: 91%

“…We attempted to use the already published FCFs for the A 2 П -X 2 Σ + system of MgF [31,32] but we refrained from that for the following reasons. Singh et al [31] used in their calculations the equilibrium bond length of 1.733 Å for the A 2 П state, much differing from the value quoted by HH (1.7469 Å [23]) -see also Table 1 of Ref.…”

Section: Estimation Of Temperature From Intensity Distribution Withinmentioning

confidence: 99%

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Characterization of plasma electrolytic oxidation of magnesium alloy AZ31 in alkaline solution containing fluoride

Stojadinović

Vasilić

Radić-Perić

et al. 2015

Surface and Coatings Technology

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Radiative transition probabilities and lifetimes for the band systems A²pi - X²sigma+ of the isovalent molecules BeF, MgF and CaF

Cited by 42 publications

References 22 publications

Diffusion, thermalization, and optical pumping of YbF molecules in a cold buffer-gas cell

Diffusion, thermalization, and optical pumping of YbF molecules in a cold buffer-gas cell

Thermal Casimir versus Casimir-Polder Forces: Equilibrium and Nonequilibrium Forces

Characterization of plasma electrolytic oxidation of magnesium alloy AZ31 in alkaline solution containing fluoride

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