Infrared Absorption and Emission Spectrum of Electron Bubbles Attached to Linear Vortices in Liquid 4He

Density functional theory of doped superfluid liquid helium and nanodroplets

“…Since trapping of impurities at vortex lines alters the surrounding liquid density distribution, it has been proposed that absorption spectroscopy of alkali metal atoms, excited state helium atoms, or electrons could be used to detect vorticity. 43,112,113 Unfortunately, the spectral changes are predicted to be very small. For this reason, the Ca atom may be a better candidate because it is just barely localised on the droplet surface.…”

“…The 1p-1s emission energy has been calculated for both free and vortex trapped ebubbles. 113 This calculation assumes that the radiative lifetime of the excited state is longer than the time required for the liquid to equilibrate around the electron. Experimental data indicate that the radiative lifetime is some tens of nanoseconds 232 or even tens of microseconds when calculated directly from the transition dipole moment.…”

Evolution of the excited electron bubble in liquidH4eand the appearance of fission-like processes

“…The evolution can be safely followed for about 25 Below 1 bar, we have found that the ebubble configuration is simply connected and radiates a sizeable part of the excitation energy as sound waves. For instance, at P = 0 bar, the energy difference between the spherical 1P configuration and the relaxed 1P quasiequilibrium configuration is ∼ 40 meV (see Fig.…”

“…In Sec. II we describe our model and present a quasi-static study of the ebubble, completing the results we have presented elsewhere, 25 and recalling some technical details about the method we have used to solve the variational equations for the fluid and the electron. In Sec.…”

“…On the contrary, if this region is not accesible to the superfluid due, e.g., to the presence of a vortex whose vorticity line coincides with the symmetry axis of the ebubble, the baby bubbles may be held together by a tiny neck. 25 It is worth pointing out that some of the quasi-equilibrium configurations displayed in…”