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The potential energy surfaces and density distributions of ground states in even-mass Be isotopes are studied by using the point-coupling covariant density functional theory with the PC-F1 effective interaction. The clustering structure is exhibited automatically in most of the Be isotopes. The results indicate that 6Be has an a+2p clustering structure, while 8,10,14 Be have the 2a clustering structure. The a-a distances and the corresponding quadrupole deformation parameters have a similar evolution trend against the neutron number. [ABSTRACT FROM AUTHOR]

In this paper, ultracold atoms and molecules in a dark magneto-optical trap (MOT) are studied via depumping the cesium cold atoms into the dark hyperfine ground state. The collision rate is reduced to 0.45 s-1 and the density of the atoms is increased to 5:6 ✕ 1011 cm-3 when the fractional population of the atoms in the bright hyperfine ground state is as low as 0.15. The vibrational spectra of the ultracold cesium molecules are also studied in a standard MOT and in a dark MOT separately. The experimental results are analyzed by using the perturbative quantum approach. [ABSTRACT FROM AUTHOR]

We investigate the production of ultracold ground state X1σ+ (v = 0) RbCs molecules in the lowest vibrational level via short-range photoassociation followed by spontaneous emission. The starting point is the laser cooled 85Rb and 133Cs atoms in a dual species, forced dark magneto-optical trap. The special intermediate level (5)0+(v = 10) correlated to the (2)3π electric state is achieved by the photoassociation process. The formed ground state X1σ+ (v = 0) molecule is resonantly excited to the 21π intermediate state by a 651 nm pulse laser and is ionized by a 532 nm pulse laser and then detected by the time-of-flight mass spectrum. Saturation of the photoionization spectroscopy at large ionization laser energy is observed and the ionization efficiency is obtained from the fitting. The production of ultracold ground state 85Rb133Cs molecules is facilitative for the further research about the manipulation of ultracold molecules in the rovibrational ground state. [ABSTRACT FROM AUTHOR]