title: Interaction of Helium Rydberg State Molecules with Dense Helium.
abstract: The interaction potentials of the He2*excimer, in the a3Σu, b3Πg, c3Σg, and d3Σuelectronic states with a ground state helium atom are presented. The symmetry of the interaction potentials closely follows the excimer Rydberg electron density with pronounced short-range minima appearing along the nodal planes of the Rydberg orbital. In such cases, a combination of the electrostatic short-range attraction combined with Pauli repulsion leads to the appearance of unusual long-range maxima in the potentials. Bosonic density functional calculations show that the3d state excimer resides in a localized solvation bubble in dense helium at 4.5 K, with radii varying from 12.7 Å at 0.1 MPa to 10.8 Å at 2.4 MPa. The calculated3d →3b pressure-induced fluorescence band shifts are in good agreement with experimental results determined by application of corona discharge. The magnitude of the spectral shifts indicate that the observed He2*molecules emit from dense helium whereas the corresponding fluorescence signal from the discharge zone appears quenched. This implies that fluorescence spectroscopy involving this electronic transition can only be used to probe the state of the surrounding medium rather than the discharge zone itself.
authors: G2ELab-GreEn-ER, Equipe MDE , 21 avenue des Martyrs, CS 90624, 38031 Grenoble Cedex 1, France.
authors: Nelly
authors: N
authors: Bonifaci
authors: Guizhou Institute of Technology 1 Caiguan Road, 550003 Guiyang, China.
authors: Zhiling
authors: Z
authors: Li
authors: Department of Chemistry and Biochemistry, California State University at Northridge , 18111 Nordhoff St., Northridge, California 91330, United States.
authors: Jussi
authors: J
authors: Eloranta
authors: Department of Biology and Chemistry, Fitchburg State University , 160 Pearl St., Fitchburg, Massachusetts 01420, United States.
authors: Steven L
authors: SL
authors: Fiedler