Superfluid Helium Nanodroplets

Setup of the ESR experiment

I. Electron Spin Resonance of 87Rb Monomers

I. Introduction Superfluid Helium Nanodroplets (HeN) are used as the perfect matrix for single atoms and small clusters because of their unique properties. Electron spin resonance (ESR) spectroscopy on HeN is a promising tool to study the environment of radicals at very low temperatures (0.38K), which could recently be demonstrated for 85Rb doped droplets [1]. […]
Rubidium recycling scheme

II. Optical Pumping of Rubidium

Rubidium D-lines     Alkali-metal and alkaline earth metal atoms do not immerse fully in HeN and reside on the surface, bound by long-range Van-der-Waals forces. The interaction with the helium environment leads to a line-broadening in the laser induced fluorescence (LIF) spectra. The 52P1/2 (2Π1/2) and 52P3/2 (2Π3/2,2Σ1/2) transitions of Rubidium are blue-shifted with […]
rubodoium 87 ESR on superfluid helium nano-droplets

III. Electron Spin Resonance Results

ODMR scheme   The ODMR scheme uses  circularly polarized pump laser light (σ+ and σ–) to  selectively address the electron spin states. The four ESR transitions take place between the eight hyperfine ground levels when a π-pulse in the fixed frequency cavity is applied.   In the indermediate magnetic field neither mF nor {mI, mJ} […]
Rubidium optical pumping

IV. Simple Pump model

Transition strengths   In zero magnetic field the transition strength may  be easily calculated with angular momentum theory and the help of the Wigner–Eckart theorem.     If there is an applied field the transition strengths differ and must be calculated taking the mixing of states into account: For intermediate fields in the range of […]
mateo_bubble_250

Excited Electron Bubble

Electron Bubbles   David Mateo made a systematic study on the excited electron-bubble states in superfluid 4Helium using a time-dependent density functional approach. For the evolution of the 1P bubble state, two different functionals accompanied with two different time-development schemes were used, namely an accurate finite-range functional for helium with an adiabatic approximation for electron […]
chrom_transition

van der Waals interactions between heliophilic and heliophobic dopants

Helium density plots of a helium nanodroplet with two impurities   In my paper I did a case study of van der Waals interactions between heliophilic and heliophobic dopants. The nano-droplet is subsequently doped with xenon, a highly polarizeable rare gas element and rubidium, an alkali-metal used as e.g. EPR spin probe. The heliophilic xenon […]
mateo_barium_250

Ionized Barium+ Snowball in HeN

The solvation of a Ba+ ion created by photoionization of neutral Barium at the surface of a 4He nanodroplet leads to the nucleation of a quantized ring vortex. In a recent work David Mateo et al. suggested that this may happen in alkali metals, too. In the ground state alkali metals sit in a dimple […]