The weakest bond: Experimental observation of helium dimer

Abstract

Helium dimer ion was observed after electron impact ionization of a supersonic expansion of helium with translational temperature near 1 mK. The dependence of the ion signal on source pressure, distance from the source, and electron kinetic energy was measured. The signal was determined to arise from ionization of neutral helium dimer.

Parametric sensitivity analysis for the helium dimers on a model potential

“…10 Sensitivity analysis was also used to invert and analyze data in quantum scattering, under Born approximation 2 and in thermodynamic analysis of the second virial data. [24][25][26] In the present work SA will be applied to system parameters variation with respect to the formation of the diatomic molecules.…”

“…Taking into account the experimental evidence for helium molecule, 25 one may argue about the potential quality. The present results have shown that, to improve the potential, it is not a matter of changing the potential parameters.…”

Some Energy Inequalities for Two-Body Problems and Helium Dimer

“…As it is known helium 4 dimer is a molecule which was observed experimentally in 1993 [8]. This dimer is the largest one that we know.…”

“…(Of course another appropriate class of trial wave functions could give a bound state in 3D, but they are unknown). As the dimer was discovered experimentally with a binding energy of 1 mK [8], or calculated 1.7 mK [15], one may estimate the trial function using the relation (14). Namely, on the right hand side of the relation (14) only a part of the first term and the second term survive for 1 = 0.…”

“…It is known that short range correlations have been described in this well. A quite new example is the helium 4 dimer, which was experimentally discovered four years ago [8] and recently approved [9,10]. Much theoretical and experimental research concerning this two-body system should be done in future.…”